SUNLIGHT AND THE SURVIVAL OF ENTERIC BACTERIA IN NATURAL-WATERS
SUNLIGHT AND THE SURVIVAL OF ENTERIC BACTERIA IN NATURAL-WATERS
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DOI：
10.1111/j.1365-2672.1991.tb02935.x
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发表时间：
1991-03-01
期刊：
影响因子：
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通讯作者：
EVISON, LM
中科院分区：
文献类型：
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作者：
DAVIES, CM;EVISON, LM
大肠杆菌和一些沙门氏菌暴露在海水和淡水中，暴露在自然阳光、强度相当的可见光和含有类似比例紫外光的光中。与自然阳光一样，但强度要低得多。在选择性和非选择性培养基上进行直接活菌计数和可培养计数。在自然阳光下，海水中可培养细菌数量的减少速度明显快于淡水中。海水和淡水中可培养细菌数量的下降率在细菌暴露在小紫外光下时没有显著差异。强度相近的成分。因此，在UV存在的情况下，盐度对可养殖性损失的影响更为显著。辐射。用吖啶橙直接活菌计数法直接计数比海水中的可培养计数下降得慢得多，但与自然阳光下淡水中的可培养计数相比，下降得更慢。在海水和淡水中，直接活体计数和可培养计数在可见光下以类似的速度下降。这可能意味着肠道细菌在暴露在自然阳光下时，在海水中进化为一种可存活但不可培养的形式。腐植酸的存在显着减少了可培养能力的损失，但仅在低盐度条件下。盐度似乎是影响暴露在阳光下的细菌可培养能力的一个重要因素。
Escherichia coli and some salmonellas were exposed in seawater and freshwater to natural sunlight, visible light of comparable intensity, and light containing a similar proportion of u.v. as natural sunlight but of a much lower intensity. Direct viable bacterial counts and culturable counts on selective and non-selective media were made at intervals. The rate of decrease in numbers of culturable bacteria was significantly faster in seawater than in freshwater when exposed to natural sunlight. No significant difference was found between the rates of decrease in numbers of culturable bacteria in seawater and those in freshwater when bacteria were exposed to light with a small u.v. component of similar intensity. The effect of salinity on loss of culturability is, therefore, more significant in the presence of u.v. radiation. Direct counts by the acridine orange direct viable count method decreased much more slowly than the culturable counts in seawater but comparably with culturable counts in freshwater in natural sunlight. Direct viable counts and culturable counts decreased at a similar rate in seawater and in freshwater in visible light. This may signify the evolution of enteric bacteria towards a viable but non-culturable form in seawater when exposed to natural sunlight. The presence of humic acids significantly reduced loss of culturability but only in low salinity conditions. Salinity appears to be an important factor influencing culturability in bacteria exposed to sunlight.