溴氰菊酯降解菌的筛选及其降解特性研究

以过期变质的溴氰菊酯农药为供试材料,采用细菌培养基初筛后,依据气相色谱法测定溴氰菊酯选择性培养基中溴氰菊酯降解率的复筛结果,筛选出2株(X_(09)、X_(20))溴氰菊酯降解菌.结果表明,过期变质的农药同样是筛选农药降解菌的重要资源;筛选出的2株溴氰菊酯降解菌X_(09)、X_(20)分别隶属于肠杆菌属(Enterobacter sp.)和假单胞菌属(Pseudomonas sp.).其降解温度为20～35℃,降解pH值为6～10.2株降解菌在培养温度为30℃条件下,溴氰菊酯降解率分别为65.6%和48.4%;在pit值为7.0条件下,溴溴氰菊酯的降解率分别为68.1%和49.5%;加大接种量(20%-25%)可以提高X_(09)的溴氰菊酯降解率(69.1%),添加1%的牛肉膏、葡萄糖、蔗糖可显著提高X_(20)溴氰菊酯降解率(69.3%).

Isolating and degrading features of deltamethrin-degrading bacteria

The purpose of this paper is to introduce our research findings on the isolation and degradation features of the deltamethrin-de-grading bacteria in degrading the effects of residue left-over by some farm-use pesticides. As a matter of fact, deltamethrin used to be regarded as a safe and secure pesticide, for which it was widely used to control harmful insects in agro-production. But, since 1999, AlMakkawy HK proved to be cumulative in bio-creatures' bodies, and some other researches even proved it carcinogenic and mutagenic to some extent though its residue of pyrethroids in agro-products were limited by FAO and WHO. As is known, biedegradation of synthetic pyrethroids is by nature merely a pathway for eliminating harmful residues from the contaminated environmental substances. In addition, when some kinds of pyrethroids degrading strains are isolated from the soil and some other substances, only a few of them, such as Bacillus sp. and Pseudomonas sp., can be used to break down the deltamethrin. In such a situation, this paper would like to select some of the strains to deltamethrin-degrade detrimental bacteria from the plant surface or from the farm soil in hoping to find out the optimal degrading conditions, such as temperature, pH value, the amounts of inoculums and the effects of other different nutritious substances while degrading the dehamethrin. In so doing, we have succeeded in isolating deltamethrin-degrading microbial strains and two deltamethrin-degrading bacteria (X_(09),X_(20) ) from it by using an invalid deltamethrin product. The result of our isolation experiments suggests that the invalid deitamethrin was also one of most important resources for isolating deitamethrin-degrading microbial strains with its own advantages, such as free from the acclimatization procedure. The results of Biolog microplate reactions indicate that the two bacteria strains (X_(09) and X_(20)) can be classified into the group of Enterobacter and that of Pseudomonas, respectively. The optimal conditions for the aerobic degradation of deltamethrin by the two strains turn out similar with the active degrading temperature and pH value being 30 ℃ and 7.0, respectively. With the increase of the active cells'amount of strains X_(09)(7.0 x 10~9 -8.3 × 10~9 cell), the degradation rate of deltamethrin can be expected to reach 69.1%. The deltamethrin degradation rate can be expected to rise to 69.3 % on the condition of adding 1% beef extract or glucose or sugar for strains X_(09).