Symbiotic adaptation of bacteria in the gut of Reticulitermes speratus: low endo-beta-1,4-glucanase activity.

The termite is a good model of symbiosis between microbes and hosts and possesses an effective cellulose digestive system. Oxygen-tolerant bacteria, such as Dyella sp., Chryseobacterium sp., and Bacillus sp., were isolated from Reticulitermes speratus gut. Notably, the endo-beta-1,4-glucanase (EG) activity of all 16 strains of isolated bacteria was low. Due to the combined activity of EG from the termites and their symbiotic protozoa, the bacteria might not be compelled to express EG. This observation demonstrates how well intestinal bacteria have assimilated themselves into the efficient cellulose digestive systems of termites.

Novel ultramicrobacterial isolates from a deep Greenland ice core represent a proposed new species, Chryseobacterium greenlandense sp. nov.

Three novel orange, ultramicrobacterial isolates, UMB10, UMB14, and UMB34(T) were isolated from enrichment cultures inoculated with a melted 3,043 m deep Greenland ice core sample. Phylogenetic analysis of the 16S rRNA gene sequences indicated that the isolates belonged to a single species within the genus Chryseobacterium. They were most closely related to Chryseobacterium aquaticum (99.3%), Chryseobacterium soli (97.1%), and Chryseobacterium soldanellicola (96.9%). Genomic hybridization showed low levels of relatedness between UMB34(T) and C. aquaticum and C. soldanellicola (19-30%) and C. soli and Chryseobacterium jejuense (45-56%). Comparative genomic fingerprinting analysis using the enterobacterial repetitive intergenic consensus (ERIC) sequence showed nearly identical banding patterns for the three isolates and these patterns were distinct from those of C. aquaticum, C. soldanellicola, C. soli, and C. jejuense. The cells were short rods, lacked flagella, had cell volumes of <0.1 mum(3), formed buds and smaller protrusions (blebs), produced copious extracellular material and a flexirubin type pigment. UMB34(T) produced acids from carbohydrates and utilized glucose and maltose although it did not assimilate mannose. The DNA G + C was 39.6-41.6 mol%. Based on the differences from validly named Chryseobacterium species, it was concluded that these isolates represent a new species for which the name, Chryseobacterium greenlandense is proposed. The type strain is UMB34(T) (=CIP 110007T = NRRL B-59357).

Isolation and description of a stable carbazole-degrading microbial consortium consisting of Chryseobacterium sp. NCY and Achromobacter sp. NCW.

A stable microbial consortium, separated from a refinery wastewater sample, was able to utilize carbazole as the sole source of carbon, nitrogen, and energy, and liberated ammonia from excess nitrogen. Two bacterial strains (NCY and NCW) were isolated from the microbial consortium using a nutrient agar plate. Based on the 16S rDNA sequence analysis, the two bacteria were identified as Chryseobacterium sp. NCY and Achromobacter sp. NCW, respectively. No intermediates of carbazole degradation were detected by high-performance liquid chromatography. The substrate specificity assay showed that the consortium could utilize compounds similar to carbazole, such as phenanthrene, naphthalene, and imidazole. Neither the pure strain NCY nor NCW could degrade carbazole after domestication for several times. It was suggested that the two bacteria formed a microbial consortium capable of metabolizing carbazole.

Invasion of murine respiratory tract epithelial cells by Chryseobacterium meningosepticum and identification of genes present specifically in an invasive strain.

Chryseobacterium meningosepticum causes severe infections in infants or adults with underlying illness. The species is highly heterogeneous, genetically composed of subgroups with different pathogenicity. Eight strains of C. meningosepticum, representing four different genomic subgroups, were evaluated for their ability to penetrate Madin-Darby Canine Kidney (MDCK) epithelial cell monolayers and serum resistance. None of the strains showed cytotoxicity or penetration to the MDCK cells. All displayed resistance to the bactericidal activity of various normal human sera. A murine pulmonary infection model was used to compare the pathogenicity between a clinical isolate and an environmental isolate. C. meningosepticum were cleared from the lung of infected mice within 7 days following the intratracheal challenge. Electron microscopy demonstrated the large membrane protrusions, indicative of ruffles, and smaller, less organized membrane structures of the respiratory epithelial cells induced by the clinical isolate. Bacteria were observed to enter the cells as single entities in spacious vacuoles. Suppressive subtraction hybridization identified in the invasive isolate 35 distinct sequences associated with systems of energy production and conversion, transport, and secretion. In most cases, the identities between the references and the amino acid sequences deduced were low, suggesting that the functions of these sequences remain unknown.