Marine bacteria and their role in polyethylene terephthalate biodeterioration and biofragmentation

Microplastic (MP) pollution is a serious threat to the terrestrial and marine environment, posing a serious threat to all living beings. Therefore, there is an urgent need to find cheap, safe, and environmentally friendly solutions to alleviate the problem.This study aimed to assess the potential of a marine bacteria community and two of its isolates to biodegrade petroleum-based polyethylene terephthalate (PET) plastic bottles and bio-based polyethylene terephthalate (BPET) plastic bags. Ultraviolet (UV) treated microplastic films (∼2 mm2), were exposed to the consortium of bacteria and isolates for 90 and 45 days, respectively. Negative (MP without inoculum) and positive (bacterial inoculum, without any MP) controls were used in parallel. During the incubation period, samples were taken every two weeks or monthly to analyse bacterial growth, the pH, and changes in the polymer functional groups using Fourier Transform Infrared spectroscopy − Attenuated TotalReflectance (FTIR-ATR). The Chemical Oxygen Demand (COD) of microplastic was also measured at the beginning and at the end of the experiments. At the end of the incubation period, MP particles were subjected to scanning electron microscopy (SEM). Bacterial growth showed a statistically significant increase in the samples inoculated with marine bacteria as compared with the negative controls. The absorbance of peaks characteristic of the PET and BPET significantly decreased in the samples containing bacteria, and new peaks also appeared. Our results showed that marine bacteria have the potential to biodegrade petroleum-based and bio-based polyethylene terephthalate (BPET) MPs. These results further highlight the importance of rethinking bioplastics as an alternative to conventional plastics and how biological recycling can provide “green route” remedial solutions for PET microplastic polluted environment and consequently decreasing the environmental footprint of plastics.A poluição por microplásticos (MPs) é uma séria ameaça para o ambiente terrestre e marinho, representando um risco para todos os seres vivos. Portanto, há uma necessidade urgente de encontrar soluções baratas, seguras e ecológicas para aliviar o problema da poluição por MPs, e diminuir a pegada ambiental dos plásticos. Este estudo teve como objetivo avaliar o potencial de uma comunidade de bactérias marinhas e dois isolados para biodegradar garrafas de polietileno tereftalato (PET), e sacos plásticos feitos a partir de polietileno tereftalato de origem biológica (BPET). Filmes destes microplásticos (∼2 mm2) foram tratados com luz ultravioleta e expostos a um consórcio de bactérias e aos isolados por 90 e 45 dias, respectivamente. Controles negativos (MPs sem inóculo) e positivo (inóculo bacteriano, sem qualquer MP) foram usados em paralelo. Durante o período de incubação, foram coletadas amostras cada duas semanas ou mensalmente para analisar o crescimento bacteriano, o pH e as mudanças nos grupos funcionais dos polímeros, usando espectroscopia de infravermelho por transformada de Fourier − Reflectância Total Atenuada (FTIR-ATR). A Demanda Química de Oxigênio (DQO) dos microplásticos também foi medida no início e no fim das experiências No final do período de incubação, as partículas de MP foram ainda submetidas a microscopia eletrônica de varredura (MEV). O crescimento bacteriano apresentou um aumento estatisticamente significativo nas amostras inoculadas com bactérias marinhas em relação aos controles negativos. A absorbância dos picos característicos do PET e BPET diminuiu significativamente nas amostras contendo bactérias, e novos picos também apareceram. Os resultados mostraram que as bactérias marinhas apresentam um potencial para biodegradar PET MPs à base de petróleo e de orígem biológica. Estes resultados destacam a importância de repensar os bioplásticos como uma alternativa aos plásticos convencionais, e como a reciclagem biológica pode fornecer soluções corretivas de “rota verde” para ambientes poluídos por microplásticos (mais particularmente, de PET MPs) e, consequentemente, diminuir a pegada ambiental dos plásticos.I would like to extend my sincere thanks to Prof. Bjørn Grung, Coordinator of the Erasmus Mundus Master in Quality in Analytical Laboratories (EMQAL) Program, for his guidance moral and material support during my studies. I would like to extend my thanks to the European Union through Erasmus Mundus Scholarship for studentship that have allowed me to conduct this thesis and the Government of the United Republic of Tanzania, Government Chemist Laboratory Authority for allowing me to take part into this master’s degree progra

Illicit Drug Users in the Tanzanian Hinterland: Population Size Estimation Through Key Informant-Driven Hot Spot Mapping

We mapped hot spots and estimated the numbers of people who use drugs (PWUD) and who inject drugs (PWID) in 12 regions of Tanzania. Primary (ie, current and past PWUD) and secondary (eg, police, service providers) key informants identified potential hot spots, which we visited to verify and count the number of PWUD and PWID present. Adjustments to counts and extrapolation to regional estimates were done by local experts through iterative rounds of discussion. Drug use, specifically cocaine and heroin, occurred in all regions. Tanga had the largest numbers of PWUD and PWID (5190 and 540, respectively), followed by Mwanza (3300 and 300, respectively). Findings highlight the need to strengthen awareness of drug use and develop prevention and harm reduction programs with broader reach in Tanzania. This exercise provides a foundation for understanding the extent and locations of drug use, a baseline for future size estimations, and a sampling frame for future research