Diversity Analysis Of Formaldehyde-degradation Bacteria In Deep Sea Sediments And Formaldehyde-degradation-related Gene Cloning

Extreme environment,such as deep sea and Antarctica,is rich in plenty of resources,especially microorganism resources,the study of which is hot all over the world.After long-term evolution and selection,these microorganisms have developed particular characteristics that allow them to survive at such environment.The study of physiological structure of cold-adapted enzyme and the detoxification mechanism of these microorganism is essential not only in scientific research but also in commercial development.However,partially due to the great difficulties in collecting samples,it remains as one of the most unknown fields.In this paper,deep-sea sediments of eastern Pacific,the Indian Ocean deep-sea sediments,sediment samples of Prydz Bay in the Antarctica were researched.A total of 323 bacteria were cultured by traditional separation method,among which were 83 bacteria that can tolerate at least 50mg/L of formaldehyde and 7 bacteria that produced cold-adapted lipase.Compared with medium-temperature enzyme,cold-adapted lipase has a very high catalytic constant(Kcat) values,while lower and more stable Michaelis constant(Km) values,especially lower activation energy and the enzyme activity in low temperature, which endue it unparalleled superiority in many fields.Therefore,cold-adapted lipase has has broad application prospects in the washing industry,food processing, bio-pharmaceutical,biotechnology and other areas of the environment.In this paper,7 lipase-producing bacteria were classified and identified by molecular marker of 16S rDNA,and their characteristics of growth,enzyme production,enzymatic nature were preliminarily studied,which established a foundation for future study of mechanism of cold-adapated enzyme and its application.Among these formaldehyde-tolerant bacteria,FA15 strain possesses strongest formaldehyde tolerance,at least 4000mg/L of formaldehyde when it completely grows,which is much higher than most of the existing paper recorded.At the same time,FA15 strain can grow in M9 medium with methanol or ethanol as sole carbon source,indicating some characteristics of methylotroph.Furthermore,when FA15 cells were broken by ultrasonic,the intracellular cell-free extracts can degrade 100mg/L of formaldehyde within three hours.This means that cell-free extracts of FA15 strain can degrade formaldehyde independently and living FA15 strain,of course,is not needed,which provides a great convenience for actual application.