Camelimonas lactis gen. nov., sp. nov., isolated from the milk of camels

Abstract

Three strains of Gram-negative, rod-shaped, non-spore-forming bacteria (M 2040(M T , M 1973(M and M 1878, isolated from milk of camels at a camel-milk production farm in the United Arab Emirates, were investigated for their taxonomic allocation. On the basis of 16S rRNA gene sequence similarities, all three strains were shown to belong to the Alphaproteobacteria and were most closely related to Chelatococcus asaccharovorans and Chelatococcus daeguensis (95.1 and 95.2 % sequence similarity to the respective type strains). meso-Diaminopimelic acid was detected as the characteristic peptidoglycan diamino acid. The predominant compound in the polyamine pattern was spermidine, and sym-homospermidine was not detectable. The quinone system was ubiquinone Q-10. The polar lipid profile included the major compounds phosphatidylcholine and diphosphatidylglycerol and moderate amounts of phosphatidylethanolamine, phosphatidylglycerol, an unidentified glycolipid and two unidentified aminolipids. Minor lipids were also detected. The major fatty acid profile, consisting of C 19 : 0 cyclo v8c and C 18 : 1 v7c, with C 18 : 0 3-OH as the major hydroxylated fatty acid, was similar to those of the genus Chelatococcus. The results of DNA-DNA hybridization experiments and physiological and biochemical tests allowed both genotypic and phenotypic differentiation of the isolates from described Chelatococcus species. Isolates M 2040 T , M 1973 and M 1878-SK2 were closely related on the basis of DNA-DNA reassociation and therefore represent a single novel species. In summary, low 16S rRNA gene sequence similarities of 95 % with Chelatococcus asaccharovorans and marked differences in polar lipid profiles as well as in polyamine patterns support the description of a novel genus and species to accommodate these strains, for which the name Camelimonas lactis gen. nov., sp. nov. is proposed. The type strain of Camelimonas lactis is M 2040 T (5CCUG 58638 T 5CCM 7696 T ).During routine bacteriological testing for Brucella species, three isolates (M 2040 T , M 1973 and M 1878-SK2) were cultivated from milk of different camels of a camel-milk production farm in the United Arab Emirates. The strains grew well on Brucella agar (Difco) but were biochemically markedly distinct from Brucella species. Further analysis by 16S rRNA gene sequencing revealed Chelatococcus species as the closest relatives, but with only 95 % sequence similarity. The alphaproteobacterial genus Chelatococcus was described by Auling et al. (1993) and, at present, the genus comprises the two species Abbreviations: pNA, p-nitroanilide; pNP, p-nitrophenyl.

The Family Beijerinckiaceae

“…Cells of Camelimonas (Kämpfer et al 2010) are Gram-negative, nonmotile, nonspore-forming rods, approximately 2 mm long and 1 mm wide. Oxidase-positive, showing an oxidative metabolism.…”

“…In both cases, the classical methods for identification of Brucella species failed because they are phenotypically very distinct. Subcultivation was done in tryptone soy agar (Kämpfer et al 2010(Kämpfer et al , 2012 and other common general media can be also employed.…”

“…Strains C. lactis M 2040 T , M 1973, and M 1878-SK2 were initially cultivated on Brucella agar (Difco) from milk of different camels of a camel milk production farm in the United Arab Emirates during routine bacteriological testing for Brucella species in 2008 (Kämpfer et al 2010). C. abortus UK34/07-5 T was initially cultured on Farrell's medium (Farrell 1974) from placental tissue following a case of abortion in a Holstein-Friesian cow in Derbyshire, UK, in 2007 (Kämpfer et al 2012).…”

Emended description of the family Beijerinckiaceae and transfer of the genera Chelatococcus and Camelimonas to the family Chelatococcaceae fam. nov.

“…The former is present as only a minor fatty acid in most of the true, monophyletic Beijerinckiaceae. The DNA G+C contents range from 63.3 to 68.7 mol% (K€ ampfer et al, 2010;Jin et al, 2015), higher than the average for Beijerinckiaceae (54.7-65.2 mol%) (Kennedy, 2005;Vorobev et al, 2011;Berestovskaya et al, 2012).…”

“…Notably, the ability to grow on C 1 compounds has not been reported for any species of the genera Chelatococcus and Camelimonas, nor have any been reported to fix dinitrogen. Major fatty acids shared by all members of these two genera are 19 : 0 cyclo !8c and 18 : 1!7c (K€ ampfer et al, 2010Jin et al, 2015;Xia et al, 2015). The former is present as only a minor fatty acid in most of the true, monophyletic Beijerinckiaceae.…”