Gut probiotic bacteria play a significant role in the host health, immunity, and survival. In aquaculture, changes in the gut microbiome of fishes affect the overall productivity and product quality. In the scenario of growing plastic pollution and associated microplastic prevalence, the current study was designed to investigate the interactions and impact of prepared polystyrene microplastics (PS-MPs) of irregular surface morphology on a probiotic bacteria Bacillus tropicus ACS1, isolated from the gut of Oreochromis mossambicus (commonly called as Tilapia). The cell viability was significantly increased along with changes in bacterial growth kinetics upon exposure to varying concentrations of PS-MPs. The microplastic exposure also increased the production of exopolysaccharides (EPS) and induced slight changes in the IR spectra of the EPS. A peak representing a carbonyl linkage that could be attributed to the glycosidic linkages between sugars disappeared following exposure to higher concentrations of PS-MPs. The interaction between the bacteria and the microplastics was visualized using scanning electron microscopy (SEM) and the colonization of the bacteria with active biofilm formation was observed. The investigation of PS-MP induced oxidative stress in the bacteria revealed the generation of reactive oxygen species (ROS) and increase in anti-oxidant enzyme concentrations, superoxide dismutase (SOD), and catalase. The study provides new insights into the effect of microplastics on gut probiotics of an economically significant aquaculture species.

中文翻译：

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聚苯乙烯微塑料与罗非鱼肠道益生菌热带芽孢杆菌 ACS1 的相互作用及其对生长动力学和代谢的影响

肠道益生菌在宿主健康、免疫力和生存中发挥着重要作用。在水产养殖中，鱼类肠道微生物群的变化会影响整体生产力和产品质量。在塑料污染日益严重和相关微塑料盛行的情况下，本研究旨在研究不规则表面形态的制备聚苯乙烯微塑料（PS-MP）对从 Oreochromis 肠道分离的益生菌热带芽孢杆菌ACS1的相互作用和影响莫桑比克鱼（俗称罗非鱼）。暴露于不同浓度的 PS-MP 后，细胞活力随着细菌生长动力学的变化而显着增加。微塑料暴露还增加了胞外多糖 (EPS) 的产生，并引起 EPS 红外光谱的轻微变化。代表羰基键的峰可能归因于糖之间的糖苷键，在暴露于较高浓度的 PS-MP 后消失。使用扫描电子显微镜（SEM）可视化细菌和微塑料之间的相互作用，并观察到细菌的定植以及活跃的生物膜形成。对 PS-MP 诱导的细菌氧化应激的研究揭示了活性氧 (ROS) 的产生以及抗氧化酶、超氧化物歧化酶 (SOD) 和过氧化氢酶浓度的增加。该研究为微塑料对具有重要经济意义的水产养殖物种肠道益生菌的影响提供了新的见解。