title: Chitinase genes in lake sediments of Ardley Island, Antarctica.
abstract: A sediment core spanning approximately 1,600 years was collected from a lake on Ardley Island, Antarctica. The sediment core had been greatly influenced by penguin guano. Using molecular methods, the chitinolytic bacterial community along the sediment core was studied over its entire length. Primers targeting conserved sequences of the catalytic domains of family 18 subgroup A chitinases detected group A chitinases from a wide taxonomic range of bacteria. Using quantitative competitive PCR (QC-PCR), chitinase gene copies in each 1-cm section of the whole sediment column were quantified. QC-PCR determination of the chitinase gene copies indicated significant correlation with phosphorus and total organic carbon concentration, suggesting a historical connection between chitinase gene copies and the amount of penguin guano input into the lake sediment. Most of the chitinase genes cloned from the historic sediment core were novel. Analysis of the chitinase gene diversity in selected sediment layers and in the fresh penguin deposits indicated frequent shifts in the chitinolytic bacterial community over time. Sequence analysis of the 16S rRNA genes of chitinolytic bacteria isolated from the lake sediment revealed that the isolates belonged to Janthinobacterium species, Stenotrophomonas species of gamma-Proteobacteria, Cytophaga species of the Cytophaga-Flexibacter-Bacteroides group, and Streptomyces and Norcardiopsis species of Actinobacteria. Chitinase gene fragments were cloned and sequenced from these cultivated chitinolytic bacteria. The phylogeny of the chitinase genes obtained from the isolates did not correspond well to that of the isolates, suggesting acquisition via horizontal gene transfer.
authors.affiliation: Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Xiao
authors.forename: Xuebin
authors.initials: X
authors.lastname: Yin
authors.forename: Jian
authors.initials: J
authors.lastname: Lin
authors.forename: Liguang
authors.initials: L
authors.lastname: Sun
authors.forename: Ziyong
authors.initials: Z
authors.lastname: You
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Fengping
authors.initials: F
authors.lastname: Wang
mesh_terms: D000864:Antarctic Regions; D001419:Bacteria / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D002688:Chitinases / Q000235:genetics*; D003081:Cold Climate; D017124:Conserved Sequence; D017931:DNA Primers; D005618:Fresh Water / Q000382:microbiology*; D014644:Genetic Variation; D019015:Geologic Sediments / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D017931:DNA Primers; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D002688:Chitinases