降解柴油嗜盐菌的筛选、鉴定及其降解特性

Screening,identification and characterization of two halophilic,diesel-degrading bacteria

柴油污染对人类健康和生态环境构成了严重威胁,微生物修复成为柴油污染治理常用的方法。以柴油为唯一碳源,筛选获得35株可利用柴油的嗜盐菌,通过测定柴油降解率筛选得到1株高效降解柴油嗜盐菌B-18;通过测定表面张力、排油圈直径,以及进行免疫溶血实验,筛选得到1株高产生物表面活性剂嗜盐菌B-2。B-2排油圈直径可达6 cm,所产生物表面活性剂将发酵液表面张力从74.88 mN·m^-1降至27.15 mN·m^-1,对3%柴油的降解率为44.80%,将该菌鉴定为嗜盐盐渍微菌属(Salimicrobium sp.)。B-18对3%柴油的降解率可达54.00%,鉴定其为盐水球菌属(Salinicoccus sp.),GC-MS方法显示,该菌能降解碳链长度在14~29的烷烃。柴油体积分数为5%时,在Gibbons培养基(GM)中B-2和B-18对柴油的降解率可由原来在无机盐培养基(MSM)中的35.52%和45.62%分别提高至49.08%和53.46%;在GM中混合接菌B-2和B-18对柴油的降解率提高至68.50%,适宜降解条件为100 g·L^-1 NaCl,温度为37℃,初始pH为7.5,降解率最高达到70.45%。通过扫描电镜发现,B-2和B-18在降解柴油时发生了形态的典型变化,嗜盐菌表面形成黏性物质,细胞呈不规则团聚,从而加速对柴油的吸收降解。高盐环境下,复合菌系B-2和B-18在柴油污染的生物修复中具有较强的应用潜力。

Pollution of diesel has posed a huge threat to human health and ecological environment,the microbial bioremediation has become a common method for controlling diesel pollution.In this experiment,35 strains were found to have ability to decompose diesel by culturing with diesel as the sole carbon source.Then,one diesel fuel-degrading halophilic bacteria,B-18,was selected using measurement of degradation rate of diesel.By measuring surface tension,oil drain ring diameter and performing immunohemolysis experiments,B-2 was screened out,which was a biosurfactant producer.B-2 showed a degradation rate of 44.80%with 3%diesel,the diameter of the oil drain ring was 6 cm and the surface tension was reduced from 74.88 mN·m^-1 to 27.15 mN·m^-1,which was identified as Salimicrobium sp.The degradation rate of B-18 for 3%diesel was 54.00%,which was identified as Salinicoccus sp.The result of GC-MS showed that the bacteria could degrade alkanes with a carbon chain length of 14-29.When the concentration of diesel was 5%,the degradation rates of B-2 and B-18 in GM could be increased from 35.52%and 45.62%to 49.08%and 53.46%.The degradation rate by microbial consortium composed of B-2 and B-18 strains could reach 68.50%.The microbial consortium was able to degrade the diesel by 70.45%under optimized conditions,referring to NaCl concentration 100 g·L^-1,37℃,pH 7.5.Through scanning electron microscopy(SEM),it was found that B-2 and B-18 had typical morphological changes during the degradation of diesel,and the surface of halophilic bacteria could form sticky substances that to interconnect the individual cells,which accelerated the absorption and degradation of diesel.In high-salt environments,the microbial consortium could be used for bioremediation of diesel contaminated environments.