title: Degradation properties of various macromolecules of cultivable psychrophilic bacteria from the deep-sea water of the South Pacific Gyre.
abstract: The deep-sea water of the South Pacific Gyre (SPG, 20°S-45°S) is a cold and ultra-oligotrophic environment that is the source of cold-adapted enzymes. However, the characteristic features of psychrophilic enzymes derived from culturable microbes in the SPG remained largely unknown. In this study, the degradation properties of 174 cultures from the deep water of the SPG were used to determine the diversity of cold-adapted enzymes. Thus, the abilities to degrade polysaccharides, proteins, lipids, and DNA at 4, 16, and 28 °C were investigated. Most of the isolates showed one or more extracellular enzyme activities, including amylase, chitinase, cellulase, lipase, lecithinase, caseinase, gelatinase, and DNase at 4, 16, and 28 °C. Moreover, nearly 85.6 % of the isolates produced cold-adapted enzymes at 4 °C. The psychrophilic enzyme-producing isolates distributed primarily in Alteromonas and Pseudoalteromonas genera of the Gammaproteobacteria. Pseudoalteromonas degraded 9 types of macromolecules but not cellulose, Alteromonas secreted 8 enzymes except for cellulase and chitinase. Interestingly, the enzymatic activities of Gammaproteobacteria isolates at 4 °C were higher than those observed at 16 or 28 °C. In addition, we cloned and expressed a gene encoding an α-amylase (Amy2235) from Luteimonas abyssi XH031(T), and examined the properties of the recombinant protein. These cold-active enzymes may have huge potential for academic research and industrial applications. In addition, the capacity of the isolates to degrade various types of organic matter may indicate their unique ecological roles in the elemental biogeochemical cycling of the deep biosphere.
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, People's Republic of China.|College of Life Science, Qingdao Agriculture University, Qingdao, 266109, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, People's Republic of China.
authors.forename: Qinghao
authors.initials: Q
authors.lastname: Song
authors.affiliation: College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, People's Republic of China. xhzhang@ouc.edu.cn.|Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, People's Republic of China. xhzhang@ouc.edu.cn.
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Zhang
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D003080:Cold Temperature; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006874:Hydrostatic Pressure; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D064307:Microbiota; D010140:Pacific Ocean; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D012623:Seawater / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D008049:Lipase; D006026:Glycoside Hydrolases; D010447:Peptide Hydrolases
keywords: Cold-adapted enzymes; Deep-sea water; Screening; South Pacific Gyre (SPG); α-Amylase