外源细菌添加对红壤吸附病毒的影响

VIRUS ADSORPTION ONTO RED SOIL AS INFLUENCED BY ADDITIONAL BACTERIA

污水中病毒往往与一些可溶性有机物质、无机胶体及菌体细胞同时存在,但很少有研究考虑菌体细胞及其分泌物对环境中病毒去向的影响。从3株代表性菌株培养液中分别获取菌体细胞及其分泌的胞外聚合物(EPS),其目的是为了:(1)比较不同红壤的病毒吸附能力;(2)明确细菌存在对红壤吸附病毒的影响;(3)评估菌体细胞及EPS影响红壤吸附病毒的相对作用权重。结果表明,4种经过灭菌处理的红壤中,红黏土和赤红壤对病毒的吸附容量最大,其次为砖红壤,而红壤土的吸附能力最弱。菌体细胞对红壤吸附病毒的影响很小,在某种土壤中甚至有促进病毒吸附的趋势,但EPS或EPS与菌体细胞同时存在显著降低了红壤对病毒的吸附能力,其降低比例分别达36%和30%,表明细菌存在降低土壤吸附病毒的现象主要由其分泌物EPS导致。本研究结果表明在评估某一介质对病毒的吸附能力时必须同时考虑细菌存在的影响,否则有可能高估其吸附容量。

Viruses usually exist simultaneously with various dissolved organic matter,inorganic colloids,and microbi- al cells in wastewater, while little has been done on effects of microbial cells and their exudates on fate of viruses in the en- vironment. In this study, bacterial cells were harvested and their exuded extraeellular polymeric substances （EPS） were ex- tracted from the media that had been used to euhivate three typical strains of bacteria. The aim is to （ 1 ） compare red soils in virus adsorption capacity; （2） investigate effect of the presence of the bacteria on virus adsorption onto the red soils; and （3） evaluate relative contributions of the bacterial cells and their exuded EPS to the effect. Results show that among the four kinds of sterilized red soils,Argiargiudic Ferrosols and Allitiargiudic Ferrosols was the highest in virus adsorption capacity, Rhodiudic Ferralosols followed, and Ferriudie Cambosols lagged behind,being the lowest. The presence of bacteri- al cells did not have much effect on the adsorption, and in a certain kind of red soil it displayed a promotive trend. However,the presence of EPS alone or of cells and EPS simultaneously significantly reduced virus adsorption capaci- ties of all the four studied soils,by 36% or 30% , respectively, which indicates that the effect of the presence of bacteria re- ducing virus adsorption by the soils is attributed mainly to the EPS bacteria exude. The findings demonstrate that it is es- sential to take into account the presence of bacteria and its effect in assessing virus adsorption capacity of a certain medium. Otherwise, it is very likely to have it overestimated.