title: Induction of Cr(VI) reduction activity in an Anoxybacillus strain under heat stress: a biochemical and proteomic study.
abstract: A bacterial strain, designated as TSB-6, was isolated from the sediments of a Tantloi (India) hot spring at 65 °C. The strain showed 98% 16S rRNA gene sequence similarity with Anoxybacillus kualawohkensis strain KW12 and was found to grow optimally at 37 °C. However, growing cells, cell suspensions, and cell-free extracts from 65 °C cultures showed higher Cr(VI) reduction activities when assayed at either 37 or 65 °C than those obtained from 37 °C cultures. On fractionation of extracts from cells grown at 65 °C, the chromate reductase activity assayed at 65 °C was found mostly in the soluble fraction. When log-phase cells growing at 37 °C were shifted to 65 °C, the stressed cells produced larger quantities of reactive oxygen species. Consequently, growth of the cells was retarded, but specific Cr(VI) reduction activity increased. 2D gel electrophoresis followed by MALDI-TOF MS/MS identified the proteins whose expression level changed as a result of heat stress. The upregulated set included proteins involved in cellular metabolism of sugar, nucleotide, amino acids, lipids and vitamins, oxidoreductase activity, and protein folding. The downregulated proteins are also involved in cellular metabolism, DNA binding, and environmental signal processing.
authors.affiliation: Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India.
authors.forename: Sangita Chowdhury
authors.initials: SC
authors.lastname: Paul
authors.forename: Preeti
authors.initials: P
authors.lastname: Jain
authors.forename: Jyotirmoy
authors.initials: J
authors.lastname: Mitra
authors.forename: Sangita
authors.initials: S
authors.lastname: Dutta
authors.forename: Pamela
authors.initials: P
authors.lastname: Bhattacharya
authors.forename: Bijay
authors.initials: B
authors.lastname: Bal
authors.forename: Debasish
authors.initials: D
authors.lastname: Bhattacharyya
authors.forename: Sujoy
authors.initials: S
authors.lastname: Das Gupta
authors.forename: Subrata
authors.initials: S
authors.lastname: Pal
mesh_terms: D058677:Anoxybacillus / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism* / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000032:analysis; D002857:Chromium / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D020869:Gene Expression Profiling; D045482:Hot Springs / Q000382:microbiology; D006358:Hot Temperature; D007194:India; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D010802:Phylogeny; D020543:Proteome / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D020543:Proteome; D012336:RNA, Ribosomal, 16S; D002857:Chromium; C074702:chromium hexavalent ion; D010088:Oxidoreductases; C063243:chromate reductase