Jiangxi Province Key Laboratory of Mining and Metallurgy Environmental Pollution Control, and School of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China.
Appl Microbiol Biotechnol. 2022 May;106(9-10):3829-3836. doi: 10.1007/s00253-022-11952-9. Epub 2022 May 10.
The limited bioavailability of PAHs in non-aqueous phase liquid (NAPL) limits their degradation. The biodegradation of phenanthrene in n-tetradecane by hydrophilic bacterium Moraxella sp. CFP312 was studied with the assistance of two polymers, chitosan and carboxymethyl cellulose (CMC). Both chitosan and CMC improved the cell hydrophobicity of CFP312 and increased the contact angle of CFP312 cells from 30.4 to 78.5 and 88.5, respectively. However, CMC increased the degradation ratio of phenanthrene from 45 to nearly 100%, while chitosan did not cause any improvement. We found that CMC was more effective than chitosan in promoting CFP312 to stabilize Pickering emulsion. In the bacteria-CMC complex system, oil was dispersed into small droplets to obtain a high emulsification index and large specific surface area. Moreover, according to the microscopic image of the bacteria-CMC emulsion droplet, we observed that the droplet surface was tightly covered by the CFP312 cells. Therefore, CFP312 cells joined with CMC can utilize phenanthrene in oil phase at the oil-water interface. This study will offer a new strategy for effective microbial degradation of hydrophobic compounds in NAPLs by hydrophilic bacteria. KEY POINTS: • Biodegradation of phenanthrene in Pickering emulsions • Pickering emulsions stabilized by hydrophilic CFP312 joined with CMC. • Phenanthrene was degraded by CFP312 at oil-water interface.
在非水相液体（NAPL）中，多环芳烃的生物利用度有限，限制了它们的降解。本研究采用亲水性细菌粘质沙雷氏菌 CFP312 对正十四烷中的菲进行生物降解，并借助两种聚合物壳聚糖和羧甲基纤维素（CMC）进行研究。壳聚糖和 CMC 均提高了 CFP312 的细胞疏水性，接触角分别从 30.4°增加至 78.5°和 88.5°。然而，CMC 将菲的降解率从 45%提高到接近 100%，而壳聚糖则没有任何改善。我们发现 CMC 比壳聚糖更有效地促进 CFP312 稳定 Pickering 乳液。在细菌-CMC 复合体系中，油被分散成小液滴，从而获得高乳化指数和大比表面积。此外，根据细菌-CMC 乳状液液滴的微观图像，我们观察到液滴表面被 CFP312 细胞紧密覆盖。因此，与 CMC 结合的 CFP312 细胞可以利用油水界面处油相中的菲。该研究为亲水性细菌有效降解 NAPLs 中疏水性化合物提供了新策略。
