title: Characterization of a new Providencia sp. strain X1 producing multiple xylanases on wheat bran.
abstract: Providencia sp. strain X1 showing the highest xylanase activity among six bacterial isolates was isolated from saw-dust decomposing site. Strain X1 produced cellulase-free extracellular xylanase, which was higher in wheat bran medium than in xylan medium, when cultivated at pH 8.0 and 35°C. Zymogram analysis of crude preparation of enzymes obtained while growing on wheat bran and birchwood xylan revealed the presence of seven and two distinct xylanases with estimated molecular weight of 33; 35; 40; 48; 60; 75; and 95 kDa and 33 and 44 kDa, respectively. The crude xylanases were produced on wheat bran medium and showed optimum activity at pH 9.0 and 60°C. The thermotolerance studies showed activity retention of 100% and 85% at 40°C and 60°C after 30 min preincubation at pH 9.0. It was tolerant to lignin, ferulic acid, syringic acid, and guaiacol and retained 90% activity after ethanol treatment. The enzyme preparation was also tolerant to methanol and acetone and showed good activity retention in the presence of metal ions such as Fe2+, Mg2+, Zn2+, and Ca2+. The crude enzyme preparation was classified as endoxylanase based on the product pattern of xylan hydrolysis. Pretreatment of kraft pulp with crude xylanases for 3 h at 60°C led to a decrease in kappa number by 28.5%. The properties of present xylanases make them potentially useful for industrial applications.
authors.affiliation: Environmental Microbiology Section, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow, Uttar Pradesh 226 001, India.
authors.forename: Abhay
authors.initials: A
authors.lastname: Raj
authors.affiliation: Environmental Microbiology Section, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow, Uttar Pradesh 226 001, India.
authors.forename: Sharad
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Microbiology Division, CSIR-Central Drug Research Institute, Jankipuram Extension Sector 10, Sitapur Road, Lucknow, Uttar Pradesh 226 003, India.
authors.forename: Sudheer Kumar
authors.initials: SK
authors.lastname: Singh
authors.affiliation: Animal Facility, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow, Uttar Pradesh 226 001, India.
authors.forename: Mahadeo
authors.initials: M
authors.lastname: Kumar
mesh_terms: D004043:Dietary Fiber / Q000382:microbiology*; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D004789:Enzyme Activation; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008031:Lignin; D008670:Metals; D008969:Molecular Sequence Data; D010636:Phenols; D010802:Phylogeny; D011532:Providencia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S; D012997:Solvents; D013696:Temperature; D014990:Xylans / Q000378:metabolism
chemical_list: D004043:Dietary Fiber; D008670:Metals; D010636:Phenols; D012336:RNA, Ribosomal, 16S; D012997:Solvents; D014990:Xylans; D008031:Lignin; D043364:Endo-1,4-beta Xylanases