Screening Of Steroid-degrading Bacteria And Study Of Related Genes

Steroid hormones,also known as steroid hormones,are a class of tetracyclic aliphatic hydrocarbon compounds having a cyclopentane polyhydrophenanthrene core.Steroid hormone compounds are widely present in animal excreta,groundwater,surface water,and soil.They have poor volatility and prolonged accumulation in the body can cause endocrine dysfunction.The problem of steroid hormone contamination in domestic water is even worse and threatens public health.However,the traditional chemical and physical treatment methods have large consumption,high cost,and other pollution,so the research on the biodegradation method of steroid hormones is of great significance.In this paper,a new type of Gram-negative bacteria Klebsiella sp.was isolated from fish ponds using MS medium containing 0.5 mM estradiol.This bacterium can use steroid hormones(such as testosterone,estradiol and methyltestosterone)as the only one.Carbon source and energy.This bacterium belongs to the genus Klebsiella of the Enterobacteriaceae by 16 S rRNA analysis.A series of experiments showed that the strain grew well at 42 °C and pH 6.0.The strain was a cocci,and its shape was short rod-shaped between spherical and rod-shaped,and its size was 1.313 ?m×0.913 ?m.The bacteria showed a zone of inhibition in a medium containing 34 ?g/ml chloramphenicol or 10 ?g/ml tetracycline.Normal growth can be achieved in 100 ?g/ml ampicillin,50 ?g/ml kanamycin,10 ?g/ml streptomycin and 50 ?g/ml gentamicin,thus having these four corresponding antibiotic resistances.High performance liquid chromatography(HPLC)showed that the degradation rate of estradiol was 53.8 %,the degradation rate of testosterone was 13.3%,and the degradation rate of methyltestosterone was 47.7%.At the same time,the whole genome sequencing analysis and transcriptome sequencing analysis of Klebsiella were performed,and 414 significant up-regulated genes and 289 significantly down-regulated genes were obtained.Among these related genes are 150 dehydrogenases(short-chain dehydrogenase,etc.),59 regulatory proteins(LysR family,LuxR family,LacI family,etc.),as well as dioxygenase and aldosterone reductase.This paper provides theoretical basis and experimental basis for the research and development of steroid hormone degrading microbial resources,the bioremediation of environmental pollutants and the research and utilization of degradation genes.