Chitinophaga polysaccharea sp. nov., an exopolysaccharide-producing bacterium isolated from the rhizoplane of Dioscorea japonica

Abstract

A novel strain designated T , belonging to the class Sphingobacteriia (phylum Bacteroidetes), was isolated from the rhizoplane of Dioscorea japonica in South Korea and was characterized taxonomically using a polyphasic approach. The strain was found to comprise Gram-stain-negative, aerobic, non-motile, non-spore-forming rods. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain belonged to the genus Chitinophaga but was clearly separated from established species of the genus Chitinophaga. 16S rRNA gene sequence similarities between strain MRP-15 T and type strains of established species of the genus Chitinophaga ranged from 90.3 to 97.8 %. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; major fatty acids, iso-C 15 : 0 and C 16 : 1 v5c) supported the affiliation of strain MRP-15 T with the genus Chitinophaga. Therefore strain MRP-15 T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga polysaccharea sp. nov. is proposed. The type strain is MRP-15 T (5KACC 17184 T 5NCAIMB 02530 T ).The genus Chitinophaga, a member of the family Chitinophagaceae in the phylum Bacteroidetes, was originally proposed by Sangkhobol & Skerman (1981 , isolated from the rhizoplane of Dioscorea japonica, was shown to belong to the genus Chitinophaga according to 16S rRNA gene sequence analysis. In this study, its detailed taxonomic position was investigated using polyphasic analyses. Strain MRP-15T was originally isolated from rhizoplane of Dioscorea japonica obtained from Geumsan (36 u 119 110 N 127 u 549 320 E). The rhizoplane of Dioscorea japonica was thoroughly suspended and the suspension was spread on potato dextrose agar (Difco) plates. The plates were incubated at 28 u C for 3 days. Single colonies were purified by transferring onto R2A agar (Difco) plates and incubating at 28 u C once again. Strain T was routinely cultured on R2A agar at 28 u C and maintained as a glycerol suspension (20 %, w/v) at 280 u C. In order to characterize strain T phenotypically, the isolate was routinely grown aerobically on R2A agar for 3 days at 28 u C and pH 7.0, except where indicated otherwise.The morphology of the isolate was observed by Gram staining and scanning electron microscopy, and motility was observed by phase-contrast microscopy (Eclipse 80i; Nikon) using cells from exponentially growing cultures. Gram staining was performed by the Burke method (Murray et al., 1994). Catalase activity was determined by assessing bubble production in 3 % (v/v) H 2 O 2 , and oxidase activity was determined using 1 % (w/v) tetramethyl-p-phenylenediamine. Carbon-source utilization and enzyme activities were tested by using API 20NE, API 50CH and API ZYM test kits (bioMérieux). Growth at 4, 10, 15, 20, 25, 30, 37, 40, 45 and 50 u C and at pH 3.0-10.0 (in increments of 0.5 pH unit) was assessed in R2A broth after Abbreviation: EPS, exopolysaccharide.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain T is KC430923. 5 days. The pH of the medium was adjus...

Chitinophaga vietnamensis sp. nov., a multi-drug resistant bacterium infecting humans

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Chitinophaga dinghuensis sp. nov., isolated from soil

“…At the time of writing, the genus Chitinophaga comprises 22 species with validly published names. Among them, seven were proposed in the past three years, C. cymbidii (Li et al , 2013), C. taiwanensis (Li et al , 2013), C. polysaccharea (Han et al , 2014), C. jiangningensis (Wang et al , 2014), C. costaii (Proença et al , 2014), C. longshanensis (Gao et al , 2015) and C. qingshengii (Cheng et al , 2015). In this study, a bacterial strain (DHOC24 T ) that was phylogenetically closely related to the genus Chitinophaga was taxonomically characterized.…”

Chitinophaga qingshengii sp. nov., isolated from weathered rock surface

“…Cells of members of the genus Chitinophaga are Gram-stain-negative, non-motile or motile by sliding, non-spore-forming rods and are oxidase-variable (Kämpfer et al , 2006; Chung et al , 2012). At the time of writing, the genus Chitinophaga comprises 19 species with validly published names, including five recently described species, Chitinophaga cymbidii (Li et al , 2013), Chitinophaga jiangningensis (Wang et al , 2014), Chitinophaga polysaccharea (Han et al , 2014), Chitinophaga taiwanensis (Lin et al , 2014) and Chitinophaga costaii (Proença et al , 2014). In this study, polyphasic characterization of a mineral-weathering bacterium (strain JN246 T ) was performed.…”