Hatice Korkmaz Güvenmez

Production of a Thermostable and Alkaline Chitinase by Bacillus thuringiensis subsp. kurstaki Strain HBK-51

This paper reports the isolation and identification of chitinase-producing Bacillus from chitin-containing wastes, production of a thermostable and alkaline chitinasese, and enzyme characterization. Bacillus thuringiensis subsp. kurstaki HBK-51 was isolated from soil and was identified. Chitinase was obtained from supernatant of B. thuringiensis HBK-51 strain and showed its optimum activity at 110°C and at pH 9.0. Following 3 hours of incubation period, the enzyme showed a high level of activity at 110°C (96% remaining activity) and between pH 9.0 and 12.0 (98% remaining activity). Considering these characteristics, the enzyme was described as hyperthermophile-thermostable and highly alkaline. Two bands of the enzyme weighing 50 and 125 kDa were obtained following 12% SDS-PAGE analyses. Among the metal ions and chemicals used, Ni2+ (32%), K+ (44%), and Cu2+ (56%) increased the enzyme activity while EDTA (7%), SDS (7%), Hg2+ (11%), and ethyl-acetimidate (20%) decreased the activity of the enzyme. Bacillus thuringiensis subsp. kurstaki HBK-51 is an important strain which can be used in several biotechnological applications as a chitinase producer.

Fontibacillus pullulanilyticus sp.nov. isolated from soil.

Gram stain‐negative, motile, catalase‐, and oxidase‐ positive strain, designated DSHK107T was isolated from soil of Cukurova University campus in Adana, Turkey. Its taxonomy was investigated using a polyphasic approach. The strain grew at 20–42 °C (optimum, 30 °C), at pH 6.0–9.0 (optimum, pH 7.0) and in 0–2.0% NaCl (w/v). 16S rRNA gene sequence analysis revealed that the strain belonged to the genus Fontibacillus; strain DSHK107T showed highest sequence similarity to type strains Fontibacillus aquaticus GPTSA 19T (97.8%) and Fontibacillus panacisegetis P11‐6T (97.0%). The major fatty acid of strain DSHK107T was anteiso‐C15:0 (46.7). The polar lipids of strain DSHK107T consisted of dihosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unknown phospholipids, four unknown lipids, three unknown glycolipids, two unknown aminophospholipids, an unknown aminolipid, and an unknown aminophosphoglycolipid. The major isoprenoid quinone was MK‐7. The DNA G+C content of DSHK107T was 42.1 mol%. DNA–DNA hybridization showed that the strain DSHK107T shared low DNA–DNA relatedness with F. aquaticus DSM 17643T, Fontibacillus solani A4STRO4T, and F. panacisegetis DSM 28129T (47, 58, and 59.3%, respectively). Thus, our results support the placement of strain DSHK107T within a separate and previously unrecognized species. On the basis of a taxonomic study using a polyphasic approach, strain DSHK107T is considered to represent a novel species of the genus Fontibacillus, for which the name Fontibacillus pullulanilyticus sp. nov. is proposed. The type strain is DSHK107T (=NCCB 100560T = DSM 100116T).