Lin Hongyang, Yang Yang, Li Yongxia, Feng Xuedong, Li Qiuhong, Niu Xiaoyin, Ma Yanfei, Liu Aijv
School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, China.
Shandong Academy of Environmental Science Co., Ltd., Jinan, China.
Front Microbiol. 2023 Feb 20;14:1122966. doi: 10.3389/fmicb.2023.1122966. eCollection 2023.
In this study, micron-sized monodisperse SiO microspheres were used as sacrificial templates, and chitosan/polylactic acid (CTS/PLA) bio-microcapsules were produced using the layer-by-layer (LBL) assembly method. Microcapsules isolate bacteria from their surroundings, forming a separate microenvironment and greatly improving microorganisms' ability to adapt to adverse environmental conditions. Morphology observation indicated that the pie-shaped bio-microcapsules with a certain thickness could be successfully prepared through LBL assembly method. Surface analysis showed that the LBL bio-microcapsules (LBMs) had large fractions of mesoporous. The biodegradation experiments of toluene and the determination of toluene degrading enzyme activity were also carried out under external adverse environmental conditions (i.e., unsuitable initial concentrations of toluene, pH, temperature, and salinity). The results showed that the removal rate of toluene by LBMs can basically reach more than 90% in 2 days under adverse environmental conditions, which is significantly higher than that of free bacteria. In particular, the removal rate of toluene by LBMs can reach four times that of free bacteria at pH 3, which indicates that LBMs maintain a high level of operational stability for toluene degradation. Flow cytometry analysis showed that LBL microcapsules could effectively reduce the death rate of the bacteria. The results of the enzyme activity assay showed that the enzyme activity was significantly stronger in the LBMs system than in the free bacteria system under the same unfavorable external environmental conditions. In conclusion, the LBMs were more adaptable to the uncertain external environment, which provided a feasible bioremediation strategy for the treatment of organic contaminants in actual groundwater.
在本研究中，微米级单分散SiO微球被用作牺牲模板，并采用层层组装法制备了壳聚糖/聚乳酸（CTS/PLA）生物微胶囊。微胶囊将细菌与周围环境隔离开来，形成一个独立的微环境，并大大提高了微生物适应不利环境条件的能力。形态学观察表明，通过层层组装法可以成功制备出具有一定厚度的扇形生物微胶囊。表面分析表明，层层组装生物微胶囊（LBMs）具有很大比例的中孔。还在外部不利环境条件（即甲苯初始浓度不合适、pH值、温度和盐度）下进行了甲苯的生物降解实验和甲苯降解酶活性的测定。结果表明，在不利环境条件下，LBMs对甲苯的去除率在2天内基本可达到90%以上，显著高于游离细菌。特别是，在pH值为3时，LBMs对甲苯的去除率可达游离细菌的四倍，这表明LBMs在甲苯降解方面保持了较高的操作稳定性。流式细胞仪分析表明，层层组装微胶囊可以有效降低细菌的死亡率。酶活性测定结果表明，在相同的不利外部环境条件下，LBMs系统中的酶活性明显强于游离细菌系统。总之，LBMs对不确定的外部环境具有更强的适应性，为实际地下水中有机污染物的处理提供了一种可行的生物修复策略。
