The aim of this study was to evaluate the use of the phenylalanyl-tRNA synthase alpha subunit (pheS) and the RNA polymerase alpha subunit (rpoA) partial gene sequences for species identification of members of the genus Lactobacillus. Two hundred and one strains representing the 98 species and 17 subspecies were examined. The pheS gene sequence analysis provided an interspecies gap, which in most cases exceeded 10 % divergence, and an intraspecies variation of up to 3 %. The rpoA gene sequences revealed a somewhat lower resolution, with an interspecies gap normally exceeding 5 % and an intraspecies variation of up to 2 %. The combined use of pheS and rpoA gene sequences offers a reliable identification system for nearly all species of the genus Lactobacillus. The pheS and rpoA gene sequences provide a powerful tool for the detection of potential novel Lactobacillus species and synonymous taxa. In conclusion, the pheS and rpoA gene sequences can be used as alternative genomic markers to 16S rRNA gene sequences and have a higher discriminatory power for reliable identification of species of the genus Lactobacillus.

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Re-examination of the genusThirty-four Acetobacter strains, representing Acetobacter aceti, Acetobacter pasteurianus, Acetobacter pomorum, Acetobacter peroxydans, Acetobacter lovaniensis, Acetobacter estunensis, Acetobacter orleanensis, Acetobacter indonesiensis and Acetobacter tropicalis, were subjected to a polyphasic study that included DNA-DNA hybridizations, DNA base ratio determinations, 16S rDNA sequence analysis and phenotypic characterization. Two novel species are proposed, Acetobacter cerevisiae sp. nov. and Acetobacter malorum sp. nov. The type strains of these species are respectively LMG 1625

The microbial composition of smear-ripened cheeses is not very clear. A total of 194 bacterial isolates and 187 yeast isolates from the surfaces of four Irish farmhouse smear-ripened cheeses were identified at the midpoint of ripening using pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR, and 16S rRNA gene sequencing for identifying and typing the bacteria and Fourier transform infrared spectroscopy and mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) analysis for identifying and typing the yeast. The yeast microflora was very uniform, and Debaryomyces hansenii was the dominant species in the four cheeses. Yarrowia lipolytica was also isolated in low numbers from one cheese. The bacteria were highly diverse, and 14 different species, Corynebacterium casei, Corynebacterium variabile, Arthrobacter arilaitensis, Arthrobacter sp., Microbacterium gubbeenense, Agrococcus sp. nov., Brevibacterium linens, Staphylococcus epidermidis, Staphylococcus equorum, Staphylococcus saprophyticus, Micrococcus luteus, Halomonas venusta, Vibrio sp., and Bacillus sp., were identified on the four cheeses. Each cheese had a more or less unique microflora with four to nine species on its surface. However, two bacteria, C. casei and A. arilaitensis, were found on each cheese. Diversity at the strain level was also observed, based on the different PFGE patterns and mtDNA RFLP profiles of the dominant bacterial and yeast species. None of the ripening cultures deliberately inoculated onto the surface were reisolated from the cheeses. This study confirms the importance of the adventitious, resident microflora in the ripening of smear cheeses.Surface-ripened cheeses can be divided into mold-ripened cheeses, such as Camembert and Brie, and bacterium-ripened cheeses, such as Reblochon, Tilsit, and brick. The latter cheeses are also called smear or red smear cheeses because of the development of viscous, red-orange smears on their surfaces during ripening. The smear is a microbial mat composed of bacteria and yeast, and these microorganisms are mainly responsible for the development of the flavor characteristics of the cheeses (5, 27). The ripening process starts with the development of yeast cells, which metabolize lactate to CO 2 and H 2 O and form alkaline metabolites, such as ammonia (5,30), that lead to deacidification of the cheese surface, enabling the growth of salt-tolerant but less acid-tolerant gram-positive catalase-positive bacteria, such as Micrococcaceae and coryneform bacteria.The microbiology of these cheeses is poorly understood. In the past, Brevibacterium linens was considered to be the major organism found on the cheese surface. However, more recent investigations show that other bacteria are also important. found that Arthrobacter nicotianae, B. linens, Corynebacterium ammoniagenes, Corynebacterium variabile, and Rhodococcus fascians were the dominant organisms in 21 brick cheeses from six German dairies, while Eliskases-Lechner and Ginzinger (7) found that although B. linens ac...

Reclassification of Paenibacillus (formerly Bacillus) pulvifaciens (Nakamura 1984) Ash et al. 1994, a Later Subjective Synonym of Paenibacillus (formerly Bacillus) larvae (White 1906) Ash et al. 1994, as a Subspecies of P. larvae, with Emended Descriptions of P. larvae as P. larvae subsp. larvae and P. larvae subsp. pulvifaciens