Choji Kaneuchi

Change in the composition of the microflora on vacuum-packaged beef during chiller storage.

Five fresh beefcut samples were divided into 10 pieces, respectively, vacuum-packaged and stored at 2 degrees C for up to 6 weeks. The average pH values of five pieces from five beef samples were 5.62 +/- 0.04 at the start of storage and 5.12 +/- 0.07 after 6 weeks of storage. The pieces were homogenized, diluted and cultivated at weekly intervals on glucose-blood-liver (BL), de Man Rogosa and Sharpe (MRS) and trypticase soya (TS) agars at 7 degrees C for 10-14 days. From plates with 30-300 colonies, or the highest number if below 30, 15 colonies were randomly picked from each of the three media used for each beef sample. Based on morphologies, SDS-PAGE whole-cell protein profiles and physio-chemical characteristics, a total of 1493 strains isolated were identified as Brochothrix thermosphacta (64), Carnobacterium divergens (79), Carnobacterium piscicola (27), Lactobacillus algidus (637), Lactobacillus sp. (4), Lactococcus piscium (270), Leuconostoc gelidum (375), Acinetobacter (3), Aeromonas (1), Bacillus (10), Corynebacterium (3), Enterobacteriaceae (1), Pseudomonas (13) or Psychrobacter (6). A wider range of organisms was isolated from TS (13 organisms) and BL (7) agars than from MRS agar (3). Leuc. gelidum, Lc. piscium and L. algidas increased in numbers during the first 3 weeks of storage from about 5 x 10(3) cfu/g to the level of about 10(8) cfu/g and persisted at this level thereafter. C. divergens and C. piscicola were inconsistently detected, but seemed to persist at the relatively low level of about 5 x 10(7) cfu/g during the last 3 weeks of storage. B. thermosphacta increased to the level of about 7 x 10(5) cfu/g during the first 2 weeks of storage, but was not detected thereafter. Remaining organisms were detected sporadically at levels of <3.5 x 10(2) cfu/g during the first 2 weeks of storage.

Taxonomic Study of Helically Coiled, Sporeforming Anaerobes Isolated from the Intestines of Humans and Other Animals: Clostridium cocleatum sp. nov. and Clostridium spiroforme sp. nov.

Thirty-three anaerobic, gram-positive, helically coiled microorganisms, of which 26 were freshly isolated from the intestinal contents of humans, mice, rats, and chickens, were the subjects of a taxonomic study. These and 48 freshly isolated Clostridium ramosum-like, noncoiled organisms were found to belong to the genus Clostridium because of their sporeforming ability. They were divided into five groups on the basis of numerous biochemical properties, the guanineplus-cytosine (G+C) contents of their deoxyribonucleic acids, and their deoxyribonucleic acid homologies. Strains of group I had straight cells and a G+C content of about 28 mol% and were identified as members of C. ramosum. Cells of the strains in the other groups were coiled. The strains of group II had a G+C content of about 28 mol% and were regarded as belonging to a new species, Clostridium cocleatum, of which strain 150 (= ATCC 29902 = NCTC 11210) is designated the type strain. Those of group III had a G+C content of about 27 mol% and were placed in Clostridium spiroforme sp. nov., of which strain VPI C28-23-1A (= ATCC 29900 = NCTC 11211) is designated the type strain. The single strain of group IV, VPI C22-44-2 (Eubacterium AQ of Moore and Holdeman), had a G+C content of 35.8 mol% and was regarded as a new but unnamed organism in the genus Clostridium. Those of group V, including the original strains of this sort reported by Fitzgerald et al., had a G+C content of about 46 mol% and were also considered to be a new but unnamed organism in the genus Clostridium.

Isolation and characterization of Lactococcus piscium strains from vacuum-packaged refrigerated beef

Aims: To characterize Gram‐positive, catalase‐negative, psychrotrophic, lactic acid‐homofermentative, non‐motile cocci isolated from vacuum‐packaged refrigerated beef using phenotypic and genotypic methods.

Lactobacillus algidus sp. nov., a psychrophilic lactic acid bacterium isolated from vacuum-packaged refrigerated beef

Lactobacillus algidus sp. nov. is described on the basis of 40 strains isolated as one of the predominant bacteria from five specimens of vacuum-packaged beef collected from different meat shops and stored at 2 degrees C for 3 weeks. These strains were quite uniform in the overall characteristics examined. They are facultatively anaerobic, psychrophilic, Gram-positive, non-spore-forming, non-motile, lactic acid-homofermentative rods. The cells occurred singly and in pairs on agar media and in rather long chains in broth media. They differed in several cultural and biochemical characteristics from the authentic meso-diaminopimelic acid-positive or psychrophilic lactic acid bacteria in the genera Lactobacillus, Carnobacterium and Brochothrix. The SDS-PAGE whole-cell protein pattern was clearly distinctive. DNA-DNA hybridization and phylogenetic analysis of 16S rDNA also failed to associate these strains closely with any of the validly described organisms used. The phylogenetic analysis showed that these strains are rather remotely but most closely related to Lactobacillus mali (93% sequence similarity), which belongs to the Lactobacillus casei/Pediococcus group. Therefore, these strains should be included in the genus Lactobacillus and considered to represent a new species, Lactobacillus algidus sp. nov. The type strain is M6A9T (= JCM 10491T).

Bacteroides microfusus, a New Species from the Intestines of Calves, Chickens, and Japanese Quails

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).

Lactobacillus fuchuensis sp. nov., isolated from vacuum-packaged refrigerated beef.

Four strains of a hitherto unknown bacterium isolated from vacuum-packaged refrigerated beef were characterized by using phenotypic and phylogenetic methods. The novel strains were Gram-positive, catalase-negative, psychrophilic, rod-shaped bacteria with lactic acid-homofermentative mechanism. Comparative 16S rDNA gene sequencing demonstrated that the unknown strains represent a novel subline within the genus Lactobacillus, close to but distinct from Lactobacillus curvatus and Lactobacillus sakei. The unknown strains were readily distinguished from all currently described members of the genus Lactobacillus by biochemical properties and SDS-PAGE whole-cell protein profiles. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Lactobacillus fuchuensis sp. nov. The type strain is strain B5M10T (= JCM 11249T = DSM 14340T).

Clostridium coccoides, a New Species from the Feces of Mice

Clostridium coccoides sp. nov. is described on the basis of 12 strains isolated from a number of fecal specimens from mice fed a high-lactose diet. The isolates are obligately anaerobic, gram-positive, sporeforming, nonmotile, coccobacillary to rod-shaped cells which occur singly, in pairs, and sometimes in chains. They differ from other clostridia principally in morphology; the nearly spherical form of the cells, particularly on agar media, is rather distinctive. The guanine plus cytosine (G+C) contents of the deoxyribonucleic acids of the new strains are 43 to 45 mol%, values similar to those of clostridia with high G+C contents, such as Clostridium sphenoides, C. oroticum, C. indolis, C. innocuum, C. barkeri, and C. nexile; however, C. coccoides can be clearly differentiated from these organisms by numerous biochemical characteristics and/or fermentation products. The type strain of C. coccoides is CLC-1 (= ATCC 29236 = NCTC 11035).

Taxonomic study of Lactobacillus mali Carr and Davis 1970 and related strains: validation of Lactobacillus mali Carr and Davis 1970 over Lactobacillus yamanashiensis Nonomura 1983

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.

A comparison of Listeria monocytogenes serovar 4b isolates of clinical and food origin in Japan by pulsed-field gel electrophoresis

Pulsed-field gel electrophoresis (PFGE) patterns of 102 L. monocytogenes serovar 4b isolates from patients and foods examined in Japan were compared with 16 isolates from foodborne listeriosis episodes which occurred in North America or Europe. Using a combination of PFGE patterns with the restriction enzymes SmaI, ApaI, AscI and Sse8387I, 82 clinical isolates from Japan were categorized into 45 PFGE types: the largest group of 17 isolates (20.7%) were of the same PFGE type as cultures from the large foodborne outbreaks which occurred in California (1985) and Switzerland (1983-1987). Twenty cultures from foods on retail sale in Japan were classified into 12 PFGE types: four isolates were of three PFGE types also recognized among isolates of clinical origin from Japan, including the predominant clinical type.

Characteristics of a Colicin Plasmid in Escherichia coli Strain B177 Isolated from a Septicemic Calf

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 Tn903 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.