[Objective]The purpose was to establish the indicating mechanism of microorganism sensitive to water pollution.[Method] The water samples were collected from monitoring sites in the center of Taihu Lake,the representative water samples and their suitable indicating microorganisms were screened out through culture experiment performed on medium.[Result] The percentages of strain B in all the water samples were no less than 50% and its quantity was first increased and then decreased as the concn. Of COD was increased. When the concn. Of COD in water sample was 15 mg/L,the colony number of strain B was 6×103 per milliliter. When the concn. Of COD in water sample was 40 mg/L,the colony number of strain B was 1×104 per milliliter. When the concn. Of COD in water sample was increased from 40 mg/L to 100 mg/L,its colony number was increased from 1×104 per milliliter to 4×104 per milliliter steadily. When the concn. Of COD was no less than 100 mg/L,the increase amplitude of colony number was enhanced sharply. When the concn. Of COD was 140 mg/L,its colony number was increased to 1.5×105 per milliliter. The strain B was gram-negative bravibacterium,its highest growing temperature was higher than 37 ℃,its lowest growing temperature range was 10-17 ℃ and its optimum growing temperature was about 30 ℃; the range of pH value suitable for its growing was 5.0-9.0 and its optimum pH value was 8.0.[Conclusion] The strain B had very good early-warning and indicating function on the organic pollution degree of water body.%[目的]建立水体污染敏感微生物的指示机制.[方法] 在太湖湖心处各监测点采取水样,通过培养基培养试验选出代表水样和适宜的指示微生物.[结果] 菌株B在各水样中的百分比不小于50%,其数量随COD浓度的增加先增加后减少.当水样的COD浓度为15 mg/L时,菌株B的菌落数为6×103 个/ml;当水样的COD浓度为40 mg/L时,其菌落数为1×104 个/ml;当COD浓度从40 mg/L增至100 mg/L时,菌落数平稳地从1×104 个/ml增至4×104 个/ml;当COD浓度不小于100 mg/L时,菌落数的增幅骤然提高;当COD浓度为140 mg/L时,菌落数增至1.5×105 个/ml.菌种B属于革兰氏阴性短杆菌,其最高可生长温度高于37 ℃,最低可生长温度范围为10～17 ℃,最适生长温度为30 ℃左右,适宜pH范围为5.0～9.0,最适pH为8.0.[结论] 菌种B对水体有机污染程度有很好的预警指示作用.
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