Deoxyribonucleic Acid Relatedness and Phenotypic Characterization of Flexibacter columnaris sp. nov., nom. rev., Flexibacter psychrophilus sp. nov., nom. rev., and Flexibacter maritimus Wakabayashi, Hikida, and Masumura 1986

Abstract

Eight unidentified fish pathogens and 10 strains received as "Flexibacfer columnaris," "Cytophaga psychrophila, " and Flexibacter marifimus were compared with the type strains of all previously described species in the genera Cytophaga and Flexibacter and with seven Flavobacferium species by determining levels of deoxyribonucleic acid (DNA) relatedness (S1 nuclease method) and by performing phenotypic tests. The name Flexibacter columnaris sp. nov. is revived for a DNA relatedness group comprising eight strains that are 75 to 100% related to strain TG 39/87 and 0 to 8% related to all of the other species studied. These strains produce flat rhizoid colonies which adhere to agar, show strong gliding movement, absorb Congo red, reduce nitrate to nitrite, and produce H,S. The guanine-plus-cytosine content of the DNA is 32 mol%. The type strain is strain NCMB 2248 (= ATCC 23463). The name Flexibacferpsychruphilus sp. nov. is revived for a DNA relatedness group comprising seven strains that are 90 to 100% related to strain NCMB 1947* (T = type strain) and 0 to 5% related to all of the other species studied. These strains produce circular, convex colonies that have regular or spreading margins and do not adhere to agar, show very slow gliding movement, do not absorb Congo red, do not reduce nitrate, and do not produce H,S. The guanine-plus-cytosine content of the DNA is 33 mol%. The type strain is strain NCMB 1947. Both F. columnaris and F . psychrophilus produce the flexirubin type of pigments, are strongly proteolytic, and do not hydrolyze (or produce acid from) any carbohydrate. Flexibacter marifimus (three strains) was shown to constitute a DNA relatedness group that is 0 to 8% related to all of the other species tested. Furthermore, this organism can be differentiated by phenotypic tests. The presence of F. marifimus in Europe is shown for the first time.Since they were first described by Davis in 1922 (9). bacteria that are pathogenic for fish and belong to the order Cytophagales have frequently been isolated from diseased marine and freshwater fishes worldwide (1). These organisms have been responsible for substantial fish mortality and economic losses.The class Flexihacteriue has recently been defined by Reichenbach and Dworkin (25) to include unicellular bacteria that are capable of gliding movement on wet surfaces (gliding bacteria) but are devoid of flagella. This class is composed of two orders; the members of the order Myxohacterales have high deoxyribonucleic acid (DNA) guanineplus-cytosine (C+C) contents (67 to 71 mol%) and a typical life cycle with fruiting bodies and microcysts, and the members of the order Cytophagales have lower G+C contents with a very wide range (28 to 67 mol%), reflecting the heterogeneity of these organisms, and do not produce fruiting bodies.The gliding bacteria isolated from diseased fish belong to the order Cytophagales and to the genera Flexihacter and Cytophaga. However, the taxonomy of these groups remains in a state of confusion. One of the main problems is the relations...

Isolation and characterization of Flavobacterium columnare (Bernardet et al. 2002) from four tropical fish species in Brazil

“…These colonial and biochemical characteristics of the bacterial test isolates are consistent with those of F. columnare (Reichenbach et al, 1974;Bernardet and Grimont, 1989;Griffin, 1992;Bernardet et al, 1996).…”

“…All four strains reduced nitrate, a characteristic of Flavobacterium species observed by Bernardet and Grimont (1989) and the other 46 strains did not reducenitrate.…”

“…Filamentous tufts of bacteria adhered to the base and sides of the flasks and some tufts hung from the surface pellicle into the broth, producing a distinct fruity odor, as indicated by Shamsudin and Plumb, (1996). On the agar, colonies were yellow-orange, flat, rather small and had irregular edges (rhizoid) but some colonies were more rhizoid than others and had different sizes and shapes, non-adherent to the agar (Figure 3), translucent, pale yellow due to flexirubin type pigments but the color was of different intensities on Anacker and Ordal agar as described by Bernardet and Grimont (1989). The properties varied among the four strains since the aspect of the colonies at the agar regular edges was a little rhizoid or a little spreading.…”

“…The identification of the isolated Flavobacterium strain was checked on the basis of the characteristic yellow-green colonies, with rhizoid edges that contained Gram negative rods exhibiting gliding motility (Shamsudin and Plumb, 1996). After purification of colonies, the four isolates were identified using the criteria as described previously by Bernardet and Grimont (1989).…”

Flavobacterium haoranii sp. nov., a cypermethrin-degrading bacterium isolated from a wastewater treatment system

“…Strains: 1, strain LQY-7 T (this study); 2, F. indicum GPTSA100-9 T (Saha & Chakrabarti, 2006); 3, F. cucumis R2A45-3 T (Weon et al, 2007); 4, F. columnare ATCC 23463 T (Bernardet & Grimont, 1989;Bernardet et al, 1996); 5, F. terrae R2A1-13 T (Weon et al, 2007); 6, F. suncheonense KACC 11423 T (Kim et al, 2006); 7, F. saliperosum S13 T (Wang et al, 2006); 8, F. cheniae NJ-26 T (Qu et al, 2008 Flavobacterium haoranii sp. nov.…”