Luo Fei, Chen Hui, Wu Xiaoxin, Liu Lili, Chen Yuean, Wang Zhiping
China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Toxics. 2022 Aug 19;10(8):485. doi: 10.3390/toxics10080485.
Since the 1990s, the raw water of Huangpu River in Shanghai, China, has intermittently encountered off-flavor contamination. In this work, the concentrations of typical odor, geosmin, in raw water of Huangpu River are found to shift along with the seasons. However, microbes recognized as the producer of geosmin such as Cyanobacteria and Actinobacteria are not consistent with the shift of geosmin. Cyanobacteria blooms in summer rather than winter, whereas Actinobacteria thrives in winter. Representational difference analysis (RDA) reveals that microbes associated with blooming algae have positive co-occurrence correlations with the concentrations of geosmin and nutrients in winter, whereas those within Cyanobacteria and Planctomycete are in a positive correlation with temperature and thrive in summer. This causes the concentration of geosmin in raw water to appear to depend on the abundance of Actinobacteria rather than that of Cyanobacteria. However, combining with the synthesis and storage properties of geosmin in algae, as well as the decomposition properties of algae with Actinobacteria, geosmin might be synthesized by Cyanobacteria in summer, which is stored in cells of Cyanobacteria and released only via the decomposition of Actinobacteria in winter. This potential olfactory mechanism of geosmin is quite different from that derived from pure culture of odor producers or correlation analysis of bacteria and odors; thus, providing insights into the mechanism of practical off-flavor events.
自20世纪90年代以来，中国上海黄浦江的原水间歇性地遭遇异味污染。在这项研究中，发现黄浦江原水中典型气味物质土臭素的浓度随季节变化。然而，被认为是土臭素产生者的微生物，如蓝细菌和放线菌，与土臭素的变化并不一致。蓝细菌在夏季而非冬季大量繁殖，而放线菌在冬季大量繁殖。代表性差异分析（RDA）表明，与藻类大量繁殖相关的微生物在冬季与土臭素和营养物质的浓度呈正共现相关性，而蓝细菌和浮霉菌门内的微生物与温度呈正相关且在夏季大量繁殖。这使得原水中土臭素的浓度似乎取决于放线菌的丰度而非蓝细菌的丰度。然而，结合土臭素在藻类中的合成和储存特性，以及藻类与放线菌的分解特性，土臭素可能在夏季由蓝细菌合成，储存于蓝细菌细胞中，仅在冬季通过放线菌的分解而释放。这种土臭素潜在的嗅觉机制与源自气味产生者纯培养或细菌与气味相关性分析的机制有很大不同；因此，为实际异味事件的机制提供了见解。
