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USJ Theses and Dissertations
  • This doctoral research delves into the transformative potential of Hyperledger Fabric Blockchain and the Internet of Things (IoT) within business management, specifically in the development and implementation of a Computerised Maintenance Management System (CMMS). It suggests that merging these advanced technologies could revolutionise maintenance management and overall system performance. The study assesses the impact on fundamental business processes within the IoT paradigm, highlighting the role of the Hyperledger Fabric blockchain network in ensuring data integrity and enhancing transparency. The integration of Blockchain protocol with IoT offers efficient data transactions, thereby improving business data management and decision-making. The research further validates the robustness of Fabric release V2.4 for CMMS development. The study concludes by emphasising the need for additional research to understand long-term implications and challenges in different business environments

  • Drama-in-Education (DiE) has been recognised as a valuable teaching pedagogy in the western world for decades, and yet it has not been fully or systematically adopted in the secondary English classes in Asian contexts, including Macau, despite the numerous reported advantages for English language teaching (ELT) in the past studies. This study explores Macau’s secondary school English teachers’ perceptions of utilising DiE in their classes. A mixed-methods research (MMR) approach was adopted in this study, consisting of three phases. First, pre-survey interviews were conducted to understand the potential major concerns about the choices of teaching approaches and the application of DiE of Macau’s secondary school English teachers. Subsequently, a questionnaire survey targeting local secondary school English teachers was administered, the results of which were cross-examined by, and integrated with, the results of two post-survey group interviews. While the results affirm the local secondary school English teachers’ positive view on DiE as an ELT pedagogy and identify their perceived advantages of DiE, the study indicates the over-determination of multi-faceted challenges to its implementation in Macau’s secondary education context. The study identifies and recommends necessary substantial changes to further the application of DiE in Macau’s secondary education milieu

  • Virtual reality (VR), a computer-generated 3D environment, allows one to navigate and possibly interact, resulting in real-time simulation of one or more of the user’s five senses (M. Gutierrez et al., 2008; Vince, 2004). Despite its history through past decades, this technology has quickly developed recently. Virtual tours and spaces have been widely used in the education, arts, and rehabilitation industries. According to research, it has significant effects on mindfulness (improving mood), cognitive development (better learning ability), and embodiment (relieving pain and medical conditions). This thesis aims to identify the conditions for Macao's single-user experience to achieve mindfulness in virtual reality through immersion and interactivity. With their various definitions, this research uses the two spectrums on the levels of immersion and interactivity, conducts four experiment settings with Macao residents, and collects qualitative questionnaires and quantitative survey data. The four settings differ as they tackle different aspects: spiritual memory, historical memory, aesthetic appreciation, and meditation through concept. The analysed results were then evaluated to seek better conditions for the local community to achieve mindfulness by immersing themselves in virtual reality

  • This study examined the acquisition of higher-order thinking skills in an English as a Second Language (ESL) classroom at a secondary school in Macau. It included an investigation of the way teaching might affect the development of higher-order thinking skills and language proficiency. This study also included an examination of the degree to which existing societal practices or values might have influenced the acquisition of higher-order thinking skills. Research instruments such as a questionnaire, a twelve-week experiment, pre-and post-tests and interview sessions were used for the data collection. The findings suggested that after twelve weeks the experimental groups developed higher synthetical and evaluative skills than the control groups which instead demonstrated better language skills. The results also identified incongruences between the curriculum and the expectations of the parents and employers

  • Macao, a developing city, has been undergoing rapid and significant changes economically, culturally, and socially, partly as a consequence of the changes to the economy brought about by the gaming and tourism industry. Changes in Macao have had a major impact on its schools. Parents have a significant impact on students in school, and Macao’s secondary schools are having to handle a range of challenges and problems brought by students and their parents, many of these as a result of the changes in the wider society of Macao. The response of many schools to the challenges faced is limited, and they understate and under-use the important role played by more developed forms of parental involvement in schools. This study examines the nature, scope and extent of the problems that secondary schools in Macao are having to handle from parents and students, how the schools are handling them, and what needs to be done in order to address the problems and handle them more effectively. Through a large scale survey, interviews and a small scale questionnaire, the thesis identifies key problems facing the schools from students and parents, and it reveals that many of Macao’s secondary schools are ill-equipped to handle these, and there are many signs that the problems are becoming more acute. The thesis finds that negative parental behavior has had a stronger effect on students than positive parental behavior, and it finds that there are several reasons why the schools, in their present state, cannot address these matters effectively. A significant gap is found between what the schools indicate they should be doing and what they are actually doing to address increased parental involvement in order to impact positively on Macao’s students. Recommendations are made for intervention and action

  • Government service mini-programs have become an integral component of eGovernment in the Greater Bay Area, and successful eGovernment is necessary for building a smart city. Service quality and citizens' trust play a vital role in urban integration and in-depth cooperation in the Bay Area. The ubiquitous nature of mini-programs based on WeChat and Alipay provides excellent flexibility in accessing government services. Technology advantages, mutual recognition of cross-border data, and online transactions bring value and benefits to citizens. However, the mechanism of mini-program adoption has not been elaborated. Homogenization, conflict of regulations, and policy effectiveness are issues of great concern. This study employed Self-Determination Theory and Motivation Theory, proposed an empirical model based on the extended SOR paradigm, and aimed to identify the critical factors determining the intention of government service mini-program adoption from the user’s perspective. Six hundred and nine valid samples were collected from Macau, Hong Kong, Guangzhou, and Shenzhen through online survey platforms. The findings suggested that service quality, trust in eGovernment, ubiquity, and social influence constituted the determinants of intention to adopt. Service quality and ubiquity were salient determinants, and a great extent of service quality and ubiquity could promote perceived value and intention. Citizens' trust in government service mini-programs was reasonable, where benevolence, integrity, and competence were crucial indicators of trust. Social influence amplified and transmitted risk perception while perceived risk significantly reduced intention. Perceived value positively associated with the four determinants and enhanced user intention; it acted as a mediator with high explanatory power in the model. Government support received positive ratings from citizens; it negatively regulated the relationship between intention and the determinants respectively, implying that excessive intervention from the government could lead to inhibition. Finally, we proposed relevant implications and suggestions for the GBA government agents and policymakers

  • Although there is a substantial body of research on the second language acquisition of adults, there is little specific research on the learning experiences of senior and very senior adults. This thesis investigates and discovers the experience of being a senior from a traditional Confucian Heritage Culture aged between 55 and 75 years old, learning English as a foreign language through various interventions, including, the introduction of an adapted version of synthetic phonics to improve pronunciation, alongside the use of andragogical and geragogical principles to accommodate and encourage the development of agency and self-directed learning. This research adopted a case study methodology to investigate the lived experiences of seniors, and investigated the participants’ subjective constructions of the situation, learning experiences, challenges, circumstances, needs, and wants with regard to the situation. Therefore, an open and exploratory case study design was selected to understand the participants and report the findings. Furthermore, this thesis identifies the challenges faced by senior and very senior learners who are post-work and post-family rearing to make recommendations from the findings to complement, enhance and empower their learning

  • Source-based summary writing is an important aspect of academic writing at the undergraduate level; it includes summarizing and paraphrasing when producing texts in essay, report, or thesis formats. For university students whose second language or foreign language is English, source-based writing can be a challenging task as it involves and requires complex cognitive processes as well as reading-and-writing demands. Organized into three phases, this mixed method, small-scale exploratory feasibility case study investigated: (i) challenges and difficulties in online and offline English source-based summary writing of English as a Foreign Language (EFL) university students in Macao, identifying the cognitive and writing processes they experienced in a timed reading-writing task; and (ii) how to design and conduct interventions that could be used to diagnose, assess, and address essay challenges in source-based summary essay writing in everyday classroom sessions. Quantitative and qualitative data were collected through a summary online writing essay using Inputlog, a keystroke logging software, and retrospective think-aloud protocol in Phase One, a source-based summary essay writing task in a quasi-experiment in Phase Two, and a survey questionnaire and error analysis of pre-test and post-test essays of the control and experimental groups in Phase Three. The processes of reading and writing in English were found to be challenging and complex for EFL university students to perform in a limited time. As an initial exploratory feasibility, efficacy trial, deliberately small scale to address issues of risk, this study found that the diagnostic assessment tools and interventions had the potential to improve the summary writing processes and proficiency of EFL students, focusing on their cognitive writing skills in everyday class sessions. The thesis recommends scaling up the research in future studies, in terms of sampling and the duration of interventions designed to improve source-based summary essay writing and the cognitive writing processes that are part of this

  • Aggression clearly has an adaptive value as it is necessary to secure resources for survival, growth, and reproduction. The Siamese fighting fish, Betta splendens, have endured a prolonged process of artificial selection for winning paired-fight contests across Southeast Asia, resulting in strains of short-fin aggressive “fighters”. Across centuries, Thai breeders have been selecting these strains by discarding loser batches and allowing winner batches to breed, claiming that they are significantly more aggressive than wild-types. This natural experiment provides a powerful context to investigate the biological basis of aggressive behaviour in fish, the topic of this thesis. To study aggression, it is important to validate and standardize behavioural assays appropriate for the species under study. Further, different aggression-eliciting stimuli, such as live opponents, 3D models, video playback, or mirror images, may elicit non-equivalent behavioural and physiological responses. For B. splendens, in particular, quantifying aggression from live fights is not ethically acceptable as the high levels of aggression of this species usually result in injuries or even death of the opponent. In Chapter II, it was shown that mirror images elicit very similar aggressive displays and endocrine responses to an interacting opponent behind a transparent partition, validating the use of this test to measure aggression in this model species. Further, it was shown that circulating levels of both androgens (11-ketotestosterone and testosterone) and corticosteroids (cortisol) increased in response to the aggression challenge, even in the absence of conflict resolution, questioning the role of these hormones during present and future aggressive contests. Using the previously validated mirror assay and also tests with live conspecifics, we assessed the impact of selection for winning by comparing, in Chapter III, male and female aggressive behaviour of lab-raised fighter and wild-type strains. The hypothesis that selection for male winners enhanced aggressive displays was confirmed, suggesting that the duration and frequency of threat and attack behaviour correlates with winning probability. However, females of the fighter strain, which are not selected for fights, were also more aggressive than wild-type females. This suggests that male and female aggression share common genetic pathways and physiological mechanisms and raises the possibility that selection for alleles that favour male aggression may have promoted intersexual genetic conflict in this species. After confirming the expected differences in aggressive behaviour between fighter and wild-type fish, the following question was whether endocrine systems, in particular those previously shown to respond to aggression, could have been targeted by the selection process. From previous studies in fish and other vertebrates, it was hypothesised that selection for winners could have increased constitutive levels of androgens or led to an enhanced androgen response to a social challenge. However, in chapter IV, it was shown that levels of 11-ketotestosterone and its response to aggression was similar in males of both strains, questioning the role of androgens in the modulation of aggression in B. splendens. On the contrary, constitutive levels of cortisol and the response of this hormone to an aggression challenge were higher in wild-type compared with fighter fish, supporting previous findings that associated high aggression with a blunted cortisol response. Overall, results from Chapter IV suggest that selection for winning had a stronger impact on the hypothalamus-pituitary-interrenal axis than in the hypothalamus-pituitary-gonadal axis. My results support the assumption of the “Challenge Hypothesis” proposed by John Wingfield and collaborators in 1990 to explain the relationship between androgens and aggression, according to which androgen levels above a reproductive baseline are a consequence of the frequency and intensity of social interactions, in particular of male-male agonistic encounters. It is becoming clear that androgens increase rapidly after an aggressive contest, independently of fight outcome. However, the function of this increase remains unclear as the frequency of aggressive displays was unrelated with post-fight androgen levels and constitutive levels of androgens, and androgen responsiveness, were similar between fighter and wild-type males. Results obtained for cortisol agree with a “corticosteroid-mediated dominance hypothesis” whereby low baseline levels and a blunted response of corticosteroids would be associated with a dominant status and high aggression. The work advances our knowledge about the endocrine regulation of aggressive behaviour in B. splendens and opens several testable hypotheses about the role of androgens and corticosteroids in the regulation of fish aggressive behaviour

  • The Job Demands-Resources (JD-R) model is one of the most influential models for studying burnout and work engagement. However, the relationship between job demands and work engagement yields inconsistent results in empirical research. This study adopted the JD-R model as the theoretical base, together with the differentiated job demands approach, to examine the inconsistent relationship between job demands (i.e., emotional labor) and work engagement. Additionally, the newly proposed job resource (i.e., transformational leadership) and its relationship between burnout and work engagement were examined. Moreover, the moderating role of personal resources (i.e., emotional intelligence) was tested. Data were collected from employees working in the hospitality industry. The results revealed that (1) surface acting correlated positively with emotional exhaustion and cynicism; (2) deep acting was positively correlated with professional efficacy, cognitive, emotional, and physical work engagement; (3) the transformational leadership style negatively predicted emotional exhaustion and cynicism, while positively predicting professional efficacy, cognitive, emotional, and physical work engagement; (4) emotional intelligence moderated the relationship between deep acting, professional efficacy, and emotional work engagement; and (5) the mediation role of burnout was found in the current study

  • Listening to children’s voices is still not considered an essential part of education in some schools, including many in Asian countries. The authority of schools and teachers is still highly valued under the continued influence of Confucian Heritage Culture in many Asian schools, including a significant number in Macao. Teachers in international schools in Asian countries often experience some difficulties when communicating with young children because of their low English proficiency and the traditional views supported by many parents who grew up with the Confucian Heritage Culture, which encourages children to be quiet in the classroom to be good listeners. This Action research took fifteen months between two school years, 2018- 2019 and 2019-2020, with two groups of four and five-year-old students in a kindergarten classroom. Documentation posters were created for young children to use the next morning to reflect on their learning. The pedagogy of listening and pedagogical documentation from the Reggio Emilia approach were implemented to discover and record young children’s ideas and interests, work with daily documentation posters, and help them reflect on documentation posters to improve their learning and develop their higher-order thinking skills. Photos and videos, observation notes with the children’s comments, documentation posters, and reflective discussions were used as interventions to collect the children’s ideas and record their learning activities. The children learned to use documentation posters to remember, think, share, and improve their learning. The children’s comments from Learning Centres, recess, and reflective discussions were used to examine their understanding of learning and higher-order thinking skills. During one Pilot Cycle and three structured data collection cycles, the children demonstrated improvement in learning for each learning project and development of their thinking skills both with and without the teacher’s support. The children demonstrated higher-order thinking skills more often from Learning Centres and recess when they had to solve problems. They also demonstrated higher-order thinking skills more often during the whole group reflective discussions than in small group reflections, when a bigger number of children joined or when they had enough time to think. The thinking skills when children were reflecting were observed to concentrate on remembering and understanding as they focused on remembering and sharing the previous day’s work. The children’s other higher-order thinking skills did not show an increase in frequency during reflective discussions. However, the children demonstrated active engagement and a range of higher-order thinking skills when the teacher asked openended questions and provided support and comments to help them to connect their learning to their past experiences. Findings indicated that the children’s learning from each Learning Centre showed change and improvement during their play over time according to their interests, indicated by their material use and comments. The research was limited by its small number of participants within their age group due to convenience sampling and the children’s relatively limited ability to demonstrate higher-order thinking skills. This study has shown how teachers could help children use daily documentation posters to develop their learning and thinking skills by visualizing their ideas and the teacher’s important role in supporting children’s learning with active listening and support in the classroom

  • Seagrasses play a critical role in coastal ecosystems worldwide, providing various ecosystem services based on their region and genus. In Southeast Asia, where seagrass biodiversity and extents are at their highest, the livelihoods and food security of many coastal communities depend on these plants. Despite their ecological and economic importance, seagrasses face global threats from human activities such as pollution and land use changes. Enhalus acoroides, a widely distributed seagrass species in the tropical Indo-Pacific region, is particularly valuable for coastal management and conservation efforts due to its size and provision of various ecosystem services. Although previous research has indicated that it is less sensitive to environmental changes than other tropical seagrass species, recent reports highlight its vulnerability to siltation and eutrophication. This dissertation aimed to examine how Enhalus responds and adapts to changes in light availability, taking into account both morphological adaptation and phenotypic plasticity. Field surveys, reciprocal transplantation field experiments, and investigations of sexual reproductive effort were conducted in the Bolinao-Anda Reef system (NW Philippines) to evaluate the impact of long-term environmental changes on Enhalus populations. The findings of this study revealed that Enhalus has the capacity to adapt its traits and survive changes in depth, light gradients, and different habitat types. This is evidenced by larger shoots in low-light environments, which is apparently a response to the reduction in light availability, as evidenced in both in situ and experimental setups. Larger leaf surface area in light-reduced setups also had higher concentration of chlorophylls a and b pigments. Transplants from light-reduced environments, although morphologically large, appeared more vulnerable (with low survival values) to environmental changes associated with translocation. Being morphologically large is therefore likely a stress response to light reduction, allocating more energy on light harvesting than sexual reproduction. Reciprocal transplantation experiments indicated a high survival rate, suggesting the potential of Enhalus for use in rehabilitation. However, despite having wider plasticity to adapt to light-limitation, they can be wiped out when threshold is reached. This thesis underscores the need for further research on Enhalus' response to stressors, genetic variation, and adaptive capacity to address conservation and management challenges

  • This thesis aims to demonstrate how Pope Benedict XVI's Eucharistic theology can be used to fill the gap it identifies in the content within the Religious Education curriculum of Macao Catholic secondary schools and also extend support to the evangelization mission carried out in these schools. The thesis is divided into three parts. The first part focuses on the ideal religious formation of teachers and students in a Catholic school should be according to the teaching and discipline of the Catholic Church and how this is presently performed in three local Catholic secondary schools. This identifies a gap between theory and practice. The gap lies in the absence of formation in the sacramental and, therefore, Eucharistic teaching of the Church. The second part elaborates on the Catholic understanding of the human person and the basic needs for the development of adolescents. It does this to ensure that when the thesis proposes a solution to fill the gap in the curriculum, that solution is appropriate to the needs of the subjects of religious education, that is the adolescents in Macao Catholic secondary schools. In the third part, the Eucharistic theology of Pope Benedict XVI is explored, along with its relevance to the curriculum of the schools under investigation. It examines how it could enhance the experience of the educational mission of these schools and responds to the needs for adolescent development. Finally, suggestions are provided as how to incorporate the Eucharistic theme in the curriculum and create a Eucharistic education program for an enhanced evangelization outcome. This research has significant implications for all those who are involved in Catholic education, particularly in secondary schools

  • The thesis identifies concerns preserving, maintaining, and developing the Catholic identity of Catholic schools in Macao, the largest providers of schooling whilst being a minority religion, and with its teachers, parents, and students coming from Catholic and non-Catholic backgrounds, cultures, and values. To understand the present situation of Catholic identity in Macao’s Catholic schools, manifesting itself in part through the Catholic ethos of schools, and to identify key features, mission, vision, values, and areas for the development of Catholic identity, together with its presence and practices, this thesis reports a study of the perceptions of, and attitudes to, Catholic identity held by three key stakeholder parties in a carefully chosen representative selection of Catholic schools: teachers, parents, and students. The thesis reports their views on what the Catholic schools are currently doing in the areas of Catholic identity, and what they consider that they should be doing in these areas. The areas of focus draw on scholarship and teachings on Catholic identity, with particular emphasis placed on documents on Catholic identity and ethos from the Vatican, Archbishop Miller, and Monsignor Stock. A large-scale empirical survey here found that there was considerable support for Catholic schools in Macao, their identity, ethos, and values from the three parties. Two emergent patterns of findings are reported concerning the steps that Catholic schools were taking to promote their identity: (a) what Catholic schools should be doing concerning Catholic identity received consistently higher scores than what they were currently doing; and (b) consistently higher support for Catholic identity came from the teachers, slightly less so from the parents, and slightly less than that from the students. The study conducted a follow-up, small-scale study to investigate why these might be the case, and it suggested that the combination of Catholic values and Chinese cultural features might explain the findings on Catholic identity in the schools. The study identifies areas for possible development of, and improvements to, the identity of Catholic schools, that take account of the local cultural contexts and the teachings of the Catholic church on identity, and how these might be addressed in practice

  • As societies globalize, mastery of a second or multiple languages has become an important index to enhance interaction in the society. In that English is a is a widely used medium of communication globally for engagement in international business, commerce, science, technology and governance, the benefits of an efficacious English language teaching force to facilitate the English acquisition process of students in classrooms around the world is highly valued. For the purpose of this study, the English language teacher efficacy instrument (ELTEI) was adapted to the local context to measure the professional efficacy of the English as a foreign language (EFL) teacher participants. The objective of the research was to investigate the degree of relationship between antecedent conditions and specific teacher efficacy in Macao. A mixed-method approach in a sequential phase design was adopted to explore the efficacy of English language teachers serving Chinese medium schools in a non-English speaking region in Asia. Phase-one employed a qualitative approach to contextualize the measurement instrument and to ascertain important characteristics of the target population. Phase-two ensured a quantitative approach to yield understanding regarding the influence of key antecedent conditions on the efficacy of English language teachers in Macao. As evidenced through multiple linear regressions and structural equation modeling, openness, neuroticism, and perceived school support were significant predictors for teacher’s self-efficacy in English teaching. Recommendations for the school management to enhance and sustain the efficacy of EFL teachers in Macao were discussed

  • Since early times, the effects of a booming sector in other sectors of a small economy have been of interest to scholars. There is a general perception that the booming Gaming sector has contributed to the overall growth in Macau through the trickle-down effect, passing on the benefits of growth to other sectors. After the liberalization of the gaming industry in 2002, this booming sector experienced several years of exponential growth, becoming the driving industry for Macao’s economy. Several scholars and researchers have dedicated their studies to the effects of the casino gaming industry as a booming sector in such a small economy. However, there is a gap in what concerns measuring the influence of the Gaming sector as a driving industry for several other sectors or following industries of Macau’s economy. The purpose of this research study is to investigate in what measure the Gaming sector in Macao leveraged the other economic sectors and how related or correlated are the different industries of Macao’s Economy. A protocol-driven understanding of the state of the art on the interrelations between economic sectors and different techniques used to study those inter-relations was conducted through a systematic literature review. Given the limited available data on the Gross Value Added (GVA), or Gross Domestic Product (GDP) on the supply side, as a central measure of economic activity in the different sectors, several possible interpolation models using auxiliary high-frequency data (indicators) were compared, to achieve the optimal model for interpolation of each variable. Several forecasts for the future performance of Macau's four major economic sectors were presented based on different regression techniques. Autoregressive Integrated Moving Average (ARIMA) models were developed to assess the dependence of the future performance of a sector’s GVA on its past performance. Optimal Vector Autoregressive (VAR) models were created to identify the explanatory power of some sectors of Macau’s economy in others. Based on available auxiliary data in high-frequency (quarterly) it was possible to interpolate the quarterly GVA per economic sector, available only in low-frequency (annually), for the major sectors of Macao’s economy. Some sectors have a considerable explanatory power on the performance of other sectors, however, the proposed regression models did not identify a clear relation between the performance of the Gaming sector and the performance of other major sectors from Macao’s economy

  • This thesis explores language teaching and language acquisition by multilingual learners using a Variation Theory approach and multilingual teaching in a university setting in Macao, China. It includes three case studies applied to students of the Spanish language in the introductory level which took place from late August to early December of the year 2017. The first study describes Macao’s multilingual language learners in the University of Macao in 2017. Based on the LEAP-Q questionnaire, a questionnaire was created to inquire all Spanish language students about their languages´ background, their motivations to learn new languages, as well as their learning strategies. The second study shows how the usage of Variation Theory techniques and multilingual teaching techniques boosted the teaching and the learning during the semester. This study employs a case study methodology, by analysing in-class multiple interactions gathering information on how multilinguals´ language background affects the pedagogical process. It analyses a total of 28 classes of 1 hour and 15 minutes. The third study presents the analysis of a questionnaire to 82 students of the initial level of Spanish language in the University of Macao, along with the analysis of interviews from 10 selected multilingual students about their linguistic background and how they experienced the semester. These interviews collected more information about the effectiveness of the Variation Theory in the semester in terms of in-class teaching and learning. From the triangulation of these three studies, some conclusions have been drawn about the advantages of using Variation Theory and multilingual teaching techniques for multilingual students, for the language teacher and ultimately also into the curricular design of foreign language teaching. In sum, that the linguistic background of students plays a major role in how they acquire a new language and, that applying Variation Theory techniques can be an immensely effective technique in a language classroom setting; suggesting that multilingual students will gain from being previously identified and placed in a separate class where these variation techniques were applied. Since this thesis focuses solely on an introductory language course, there is ground to explore this same approach on more advanced multilingual language learners

  • The demand for plastic has led to enormous plastic waste in the environment, which persist and negatively impact the ecosystems. Polyethylene terephthalate (PET) is one of the most common thermoplastic polymers available on the market. The concerns about plastic waste generated an interest in strategies to enhance its biodegradation and finding alternative polymers. In this work was investigated the possibility of using bacteria to degrade PET and to produce bioplastics (Polyhydroxyalkanoates, PHAs). Finally, the integration of the two processes was tested. Overall, the work aimed to investigate the potential to recycle PET into bioplastic using bacteria. The potential of bacterial consortia from various environmental samples to degrade PET granules in liquid matrix was investigated. . The results revealed maximum PET granules degradation of 1.1 % by one of the tested consortia. PET degradation intermediate terephthalic acid (TPA) was not detected at the end of 55 days. Fourier-transform infrared spectroscopy (FTIR) results showed major spectral peak shifts and bends on PET chemical structure compared to non-inoculated control. The biodegradation of PET films buried in the soil (A), with mangrove plants (B), and bioaugmented with a bacterial consortium (C) was also investigated. The experiments were conducted for 270 days at ambient conditions. The results revealed no difference between treatments in the degradation, with a maximum weight loss of 0.118 % in the bioaugmented treatment. Nevertheless, Scanning Electron Microscope (SEM) and FTIR results indicated significant surface changes, spectral peak shifts, and stretches in PET chemical structures. Bacterial consortia isolated from the soil of the experimental treatments were assessed for degradation of PET monomers, TPA and monoethylene glycol (MEG), and intermediate Bis(2-hydroxyethyl) terephthalate (BHET). The consortia were inoculated in flasks containing minimal media with 1000 mg/L TPA or BHET or1113 mg/L MEG as the sole carbon source. Results showed complete degradation of TPA and significant degradation of BHET (96.09%), and MEG (83.65%) by the consortia. In the second part of the study, bacteria were isolated from various environmental samples and screened for PHA production using Sudan Black B staining on colonies and smeared glass slides. Transmission Electron Microscope images were captured to confirm the intracellular PHA inclusions. A total of 35 isolates were screened for PHA, and 22 showed positive staining. The isolate showing higher levels of PHA synthesis (EC2-30-3) was identified based on 16S rRNA gene sequence as Bacillus sp. and selected for PET monomers degradation and fermentation cultures for PHA production. It was cultured in minimal (Moreira et al., 2013) media with 1000 mg/L TPA and 1113 mg/L MEG as the carbon source for eight days. The isolate grew better in media containing MEG, which was selected as a substrate model for PHA fermentation. To integrate PET monomers biodegradation and production of PHA, the isolate was cultured in 0.2 % MEG. A control with 0.2 % of glucose was prepared, and the cultures were incubated for 96 hours. Bacillus sp. EC2-30-3 showed higher PHA accumulation in media supplied with MEG (40.31%) than glucose (25.53%). This is the first report showing that Bacillus sp. uses PET monomer as carbon source to produce a biopolymer. FTIR results of the extracted PHA identified its functional units as C–H, CH3, C=O, and C–O groups. The absorption bands obtained are closely related to the structure of PHB. The study thus confirmed the ability of the isolated bacteria to degrade PET monomers and produce biopolymers. The results of this work open the possibility for upscaling the use of bacteria to mitigate the impact of PET on the environment while producing environmentally friendly bioplastics

Last update from database: 4/4/25, 10:01 PM (UTC)