The fatty acid compositions and multiple antibiotic resistance patterns of 32 strains of Bradyrhizobium japonicum correlated with two major deoxyribonucleic acid homology groups. In group I, the fatty acid composition was 1.3% 16:l cis9 acid, 3.6% 16:lC acid, 8.8% 16:O acid, 1.2% 19:0 cyclopropane acid, and 81.2% 18:l acid. Group I1 contained 0.5% 16:lC acid, 11.1% 16:O acid, 0.8% 17:O cyclopropane acid, 24.7% 19:O cyclopropane acid, and 62.3% 18:l acid. Group I strains were susceptible to rifampin (500 pglml), tetracycline (100 pglml), streptomycin (100 pg/ml), chloramphenicol (500 pg/ml), erythromycin (250 pglml), carbenicillin (500 pg/ml), and nalidixic acid (50 pg/ml), whereas group I1 strains were resistant to these antibiotics. Both groups were resistant to trimethoprim (50 pg/ml) and vancomycin (100 pglml).Bradyrhizobium japonicum (Jordan 1982) (formerly Rhizobium japonicum) is the slow-growing symbiont of soybeans. This species is comprised of two highly divergent taxonomic groups which should be phenotypically distinguishable. The deoxyribonucleic acid (DNA)-DNA hybridization studies of Hollis et al. (8) established DNA homology groups I, Ia, and 11. These groups were characterized with respect to acidic extracellular polysaccharide composition and phenotypic ex planta nitrogenase expression. Groups I and Ia were reported to be quite distinct from DNA homology group I1 according to both of these criteria (9). Using some of the same strains, Stanley et al. (21) characterized the DNA nucleotide sequence divergences in and proximal to known symbiotic genes and concluded that strains of B . japonicum comprise two symbiotic genotypes (sTI and sTII) consistent with separate species designations.Whole-cell fatty acid profiles of strains grown under standardized conditions have been used for identification (1, 4,18) and classification of many bacteria (10, 17), but not in the genus Bradyrhizobium. Pankhurst et al. (20) correlated rifampin resistance in some slow-growing rhizobial strains with in vitro nitrogenase activity. This observation, together with that of Huber et al. (9) that only DNA homology group I1 strains express nitrogenase in vitro, suggested to us that patterns of antibiotic resistance might also distinguish the groups. In this paper we report that whole-cell fatty acid profiles correlate with DNA homology groups I and I1 of Hollis et al. (8) and that patterns of high-level resistance to antibiotics distinguish the two DNA homology groups. MATERIALS AND METHODSBacterial strains. All USDA strains were obtained from H. H. Keyser and D.Weber, U. S. Department of Agriculture (USDA), Beltsville, Md.; strain ATCC 10324 was obtained from the American Type Culture Collection, Rockville, Md.; strains 5631, 5633, D193, D209, THA6, and 8' were obtained from G. H. Elkan, North Carolina State University, Raleigh; and strains 61A.50 and 61A76 were obtained from S. Smith, Nitragin Co., Milwaukee, Wis. Strains that exhibit rifampin resistance and tetracycline resistance were purified by streaking onto a mediu...

Objective The screening of traditional fermented products is essential for the assessment of safety, security and further development of functional foods for the well-being of human health. The aim of the present study was to isolate and identify bacteria from fermented raw milk samples that exhibit health benefit upon consumption. Method In order to confirm the isolates as probiotics, several in-vitro assays were conducted to assess the probiotic properties of isolated bacteria. The initial screening includes tolerance to acid, bile, pancreatin and NaCl. The cell surface properties demonstrate their interaction with mucosal epithelium, which includes hydrophobicity and auto-aggregation assay. Safety assessment was done by performing hemolytic test and antibiotic susceptibility test. The antagonistic activity of probiotic strain was further evaluated against some pathogenic bacteria. Results Lactobacillus plantarum isolated from fermented raw milk was preliminarily identified by biochemical tests and further confirmed using 16S rRNA identification. The isolate designated as L. plantarum strain GCC_19M1, demonstrated significant tolerance to low pH, 0.3 % bile, 0.5 % pancreatin and 5 % NaCl. In the presence of simulated gastric juice (at pH 3), the isolate exhibited a survival rate of 93.48 to 96.97 %. Further, the development of ecological niches in the human gut and their successful accumulation has been revealed by auto-aggregation and hydrophobicity properties. Absence of hemolytic activity ensures the non-virulent nature of the strain. L. plantarum strain GCC_19M1 showed susceptibility towards towards gentamicin, tetracycline, kanamycin, meropenem and ceftriaxone, and exhibited an antagonistic effect on pathogenic bacteria. Conclusion The obtained results conveyed that L. plantarum strain GCC_19M1 has strong probiotic potential, and its presence in the fermented raw milk products may serve as a potent functional probiotic food.

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