Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, China.
Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, China.
Environ Int. 2019 Oct;131:104998. doi: 10.1016/j.envint.2019.104998. Epub 2019 Jul 19.
The omnipresence of filterable bacteria that can pass through 0.22-μm membrane filters demands a change in the sterile filtration practice. In this study, we identified that filterable bacteria enriched from a surface water are members of the Bacteroidetes, Proteobacteria, Spirochaetae, Firmicutes, and Actinobacteria. Filterable bacteria displayed superior filterability during the entire bacterial growth phase, especially at the exponential phase. Maximal passage percentages were comparable at different cell densities, and achieved earlier at high cell density. Furthermore, filter retention for the investigated bacteria is independent of liquid temperature. However, cultivation temperature could affect the growth of some specific filterable bacteria and lead to variability in the passage percentage. Additionally, membrane materials, pore size and filtering flux greatly affected the passage of filterable bacteria. The majority of filterable Hylemonella and SAR324 could pass through 0.1-μm polyvinylidene fluoride and polyethersulfone filters but could not pass through 0.1-μm polycarbonate and mixed cellulose esters filters. Taken together, our results demonstrated that the ultra-small size of filterable bacteria, membrane characteristics and filtration operational conditions could challenge the validity of the 0.22/0.1-μm sterilizing grade filters in providing bio-safety barriers.
无处不在的可滤过细菌可以通过 0.22μm 膜过滤器，这就要求改变无菌过滤的实践。在这项研究中，我们从地表水中鉴定出可滤过细菌是拟杆菌门、变形菌门、螺旋体门、厚壁菌门和放线菌门的成员。可滤过细菌在整个细菌生长阶段表现出优异的滤过性，尤其是在指数生长期。在不同的细胞密度下，最大的通过百分比相当，在高细胞密度下更早达到。此外，所研究的细菌的膜截留率与液体温度无关。然而，培养温度可能会影响某些特定可滤过细菌的生长，并导致通过百分比的变化。此外，膜材料、孔径和过滤通量极大地影响可滤过细菌的通过。大多数可滤过的海利蒙氏菌和 SAR324 可以通过 0.1μm 的聚偏二氟乙烯和聚醚砜过滤器，但不能通过 0.1μm 的聚碳酸酯和混合纤维素酯过滤器。总之，我们的结果表明，可滤过细菌的超小尺寸、膜特性和过滤操作条件可能会对 0.22/0.1μm 除菌级过滤器提供生物安全屏障的有效性提出挑战。
