Bacteroides microfusus sp. nov. is described on the basis of 16 strains isolated from a number of fecal or cecal specimens from calves, chickens, and Japanese quails. The isolates are obligately anaerobic, gram-negative, nonsporeforming, nonmotile, relatively small rods with pointed ends; the cells occur singly, in pairs, and sometimes in short chains. B. microfusus differs from other species in the genus Bacteroides principally in morphology; the small spindle-shaped cells, particularly on agar media, are rather distinctive. The guanine-plus-cytosine contents of the deoxyribonucleic acids of the new strains range from 59 to 61 mol%, the highest value so far detected in the genus Bacteroides. The new strains are similar to those of B. putredinis, B. furcosus, B. amylophilus, and B. succinogenes in fermenting a relatively small number of carbohydrates; however, B. microfusus can clearly be differentiated from these organisms by numerous biochemical properties and/or fermentation products. The type strain of B. microfusus is Q-1 (= ATCC 29728 = NCTC 11190).
Abstract A colicin plasmid in Escherichia coli strain B177 isolated from a septicemic calf was characterized. The colicin type was identified as ColV by using reference ColV producers. The colicin plasmid was labeled with transposon Tn 903 and subjected to conjugation. The transconjugants examined suggest that the colicin plasmid confers serum resistance. There was no difference in siderophore utilization ability between the transconjugants and host strain SF800. Bioassay for siderophore suggests that the colicin plasmid specifies the production of iron‐chelating compounds available for the host strain.
A total of 309 strains of thermophilic Campylobacter isolated from cats, dogs, pigs, and seagulls were examined for the susceptibility to 8 antimicrobial agents. The seagull strains consisting of 62 of C. jejuni, 31 of C. coli, and 34 of C. laridis were all susceptible to ampicillin, chloramphenicol, erythromycin, kanamycin, streptomycin, and tetracycline, showing MIC50s of 0.5 to 4 μg/ml, MIC90s of 1 to 16 μg/ml, and MIC ranges of≤ 0.125 to 16 μg/ml except a few strains of C. jejuni and C. laridis which were slightly to moderately resistant to ampicillin or tetracycline. To nalidixic acid, the strains of C. jejuni and C. coli were susceptible, but those of C. laridis were highly resistant. To cephalothin, they were all highly resistant with MIC50s of >128 μg/ml. In contrast, the strains consisting of 45 of C. jejuni from cats and dogs, 127 of C. coli from cats, dogs, and pigs, and 10 of C. laridis from dogs and pigs showed much wider MIC ranges for erythromycin, kanamycin, nalidixic acid (except C. laridis strains), streptomycin, and tetracycline due to the incidence of resistant strains. The incidence rates of resistance were in the range of 0 to 30% depending on the difference in the bacterial species and the origins. The highest incidence rates were observed mostly in C. coli strains from pigs. To ampicillin, cephalothin, and chloramphenicol, the strains represented the susceptibilities comparable to those of seagull strains.
A total of 170 fecal samples from black-headed and black-tailed seagulls collected along the coast of Tokyo Bay and at the estuary of the Sagami River were examined for thermophilic campylobacters. Of these, 51 (30.0%) were found to contain the campylobacters by at least one of culture procedures used, which consisted of both direct plating culture on a modified Skirrow's agar and enrichment cultures in four broths, Blaser's, CEM, Doyle-Roman's, and Preston, each followed by plating on the Skirrow's agar. Eleven samples (6.5%) were positive in the direct plating procedure and 50 samples (29.4%) were positive in one or more of the enrichment procedures. No single procedure detected all the positive samples. The highest recovery rate (18.8%) was obtained by an enrichment procedure using Preston broth. The isolation rate in black-headed gulls (41.4%) was higher than that in black-tailed gulls (22.0%). Eighty-seven strains isolated were identified as C. jejuni (44 strains), C. coli (20 strains), and C. laridis (23 strains) by biochemical characteristics. Their respective recovery rates were 14.1, 7.6, and 9.4%. DNA homology indices of 2 strains of C. laridis to 4 strains of C. jejuni, 3 strains of C. coli, and 4 strains of C. laridis were 12 to 19, 10 to 17, and 75 to 99%, respectively. The seagull strains with nalidixic acid resistance (30μg/ml) were also identified as C. laridis by DNA-DNA hybridization test.
Digestion with Sal I facilitated the subclassification of 41 strains of Campylobacter jejuni into seven types, and digestion with Sma I enabled subclassification into twelve types. Sma I was potentially more useful for the detection of variability among the 41 strains, but both restriction enzymes seemed to be potentially useful for detecting variability among crossed-field gel electrophoresis profiles of the strains. The results clearly demonstrated that C. jejuni strains from different sources and with different routes of transmission had invaded the three farms investigated. At farms Sa and Ai, approximately 70% (23 strains) of isolates of C. jejuni (33 strains) were subclassified into the two major genotypes (I and II) on the basis of cleavage profiles with both Sal I and Sma I. These two major genotypes appeared to have invaded, expanded in and occupied the two chicken farms. All nine strains from farm Ai belonged genotype I.
Pulsed-field gel electrophoretic profiles of the respective, undigested and intact chromosomal DNAs, prepared from three species of thermophilic Campylobacter (C. coli, C. jejuni and C. lari) demonstrated that the chromosomal DNAs from C. coli JCM 2529T, four isolated strains of C. coli, C. jejuni JCM 2013 and four isolated strains of C. jejuni migrated to around 1, 900kb, and the chromosomal DNAs from C. lari JCM 2530T migrated to around 1, 640kb. Chromosomal DNAs from 15 isolated strains of C. lari also migrated to almost the same extent as the DNAs from the C. lari type strain to around 1, 640kb. This result clearly demonstrates that pulsed-field gel electrophoresis (PFGE) is useful for the discrimination of C. lari from two other thermophilic species of Campylobacter (C. coli and C. jejuni).When the chromosomal DNAs prepared from the three Campylobacter species were digested with the restriction enzyme ApaI, electrophoretic profiles of the undigested chromosomal DNAs also demonstrated PFGE to be useful for that discrimination.
Six motile Lactobacillus strains with meso-diaminopimelic acid in their cell walls were isolated from fermented cane molasses in Thailand and were compared with three strains labeled Lactobacillus mali (strains JCM 1116T [T = type strain], JCM 3821, and JCM 3822) and with a strain labeled Lactobacillus yamanashiensis (strain JCM 1153T). Morphological, biochemical, and chemotaxonomic characteristics of these 10 strains were similar, and the levels of deoxyribonucleic acid-deoxyribonucleic acid homology among the strains revealed that they belong to a single species, Lactobacillus mali Carr and Davis 1970, which has precedence according to the International Code of Nomenclature of Bacteria.
Three restriction enzymes ApaI, SalI and SmaI, among nine enzymes tested, were found to produce distributions of DNA fragments which were useful for analysis of chromosome-sized DNA from thermophilic Campylobacter laridis by pulsed-field gel electrophoresis. From experiments with C. laridis JCM2530T and four isolates of C. laridis, the size of the genome of C. laridis was calculated to range from 1,590 to 1,700 kb, with a mean of 1,640 kb. An SmaI restriction map was derived by the partial digestion of the DNA from C. laridis JCM2530T.
A total of 692 rats, mostly Rattus rattus, which had been trapped in restaurants and food shops within the nine buildings of central Tokyo during a period from August 1988 to March 1990, were examined for Listeria spp. organisms in the large intestine contents. The organisms were detected from 133 of 692 (19.2%) samples, ranging from 9.0 to 44.8% depending on the buildings. L. monocytogenes and L. innocua were isolated from 60 (8.8%) and 73 (10.5%) rats, respectively. The perdominant serotypes of 60 isolates of L. monocytogenes were 4b (21 strains), 1/2b (20 strains), and 1/2a (14 strains).
The mutagenicity of 15 household dog urine specimens were measured by the combination of blue rayon extraction and ultramicro forward-mutation method with Salmonella Typhimurium TM677 strain. A good dose-response relation was observed between the urine volume and mutation frequency. The minimum amount of urine required was 20 ml or less. The specific mutation frequency of urine greatly varied from one dog to another. The average specific mutation frequencies in the presence and absence of S9 mix were 28.7 ± 51.5 (× 10-4) and 12.0 ± 13.3 (× 10-4), respectively, and there was no significant difference between them. The mutation frequency markedly increased after the ingestion of broiled fish. Ten human urines specimens showed a similar level of specific mutation frequency to that of the dog urine specimens in both the presence and absence of S9 mix.
