Chitinimonas taiwanensis gen. nov., sp. nov., a novel chitinolytic bacterium isolated from a freshwater pond for shrimp culture.

A bacterial strain, designated cfT was isolated from surface water of a freshwater pond for shrimp (Macrobrachium rosenbergii) culture at Ping-Tung (Southern Taiwan). Cells of this organism were Gram-negative, slightly curved rods which were motile by means of a single polar flagellum. Strain cfT utilized chitin as the exclusive carbon, nitrogen, and energy source for growth, both under aerobic and anaerobic conditions. Optimum conditions for growth were between 25 and 37 degrees C, 0 and 1% NaCl and pH 6 to 8. Strain cfT secreted two chitinolytic enzymes with approximate molecular weight 52 and 64 kDa, which hydrolyzed chitin to produce chitotriose as major product. Sequence comparison of an almost complete 16S rDNA gene showed less than 92% sequence similarity with known bacterial species. Phylogenetic analysis based on the neighbour-joining and other methods indicated that the organism formed a distinct lineage within the beta-subclass of Proteobacteria. The predominant cellular fatty acids of strain cfT were hexadecanoic acid (about 29%), octadecenoic acid (about 12%) and summed feature 3 (16:1 omega7c or 15 iso 2-OH or both [about 49%]). Its DNA base ratio was 62.8 mol% G+C. We propose to classify strain cfT (= CCRC 17210T = LMG 22011T) as Chitinimonas taiwanensis gen. nov., sp. nov.