Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats. evolutionary genomics ͉ fermentation L actic acid bacteria (LAB) are historically defined as a group of microaerophilic, Gram-positive organisms that ferment hexose sugars to produce primarily lactic acid. This functional classification includes a variety of industrially important genera, including Lactococcus, Enterococcus, Oenococcus, Pediococcus, Streptococcus, Leuconostoc, and Lactobacillus species. The seemingly simplistic metabolism of LAB has been exploited throughout history for the preservation of foods and beverages in nearly all societies dating back to the origins of agriculture (1). Domestication of LAB strains passed down through various culinary traditions and continuous passage on food stuffs has resulted in modern-day cultures able to carry out these fermentations. Today, LAB play a prominent role in the world food supply, performing the main bioconversions in fermented dairy products, meats, and vegetables. LAB also are critical for the production of wine, coffee, silage, cocoa, sourdough, and numerous indigenous food fermentations (2).LAB species are indigenous to food-related habitats, including plant (fruits, vegetables, and cereal grains) and milk environments. In addition, LAB are naturally associated with the mucosal surfaces of animals, e.g., small intestine, colon, and vagina. Isolates of the same species often are obtained from plant, dairy, and animal habitats, implying wide distribution and specialized adaptation to these diverse environments. LAB species employ two pathways to metabolize hexose: a homofermentative pathway in which lactic acid is the primary product and a heterofermentative pathway in which lactic acid, CO 2 , acetic acid, and͞or ethanol are produced (3).Complete genome sequences have been published for eight fermentative and commensal LAB species: Lactococcus lactis, Lactobacillus plantarum, Lactobacillus johnsonii, Lactobacillus acidophilus, Lactobacillus sakei, Lactobacillus bulgaricus, Lactobacillus salivarius, and Streptococcus thermophilus (4-11). This study examines nine other LAB genomes representing the phylogenetic and functional diversity of lactic acid-producing microorganisms. The LAB have small genomes encoding a range of biosynthe...

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Ozone, chlorine and heat applications were compared for killing effectiveness against food spoilage bacteria in synthetic broth. Fresh 24‐h bacterial cultures of Pseudomonas fluorescens (ATCC 948), Pseudomonas fragi (ATCC 4973), Pseudomonas putida (ATCC 795), Enterobacter aerogenes (ATCC 35028), Enterobacter cloacae (ATCC 35030) and Bacillus licheniformis (ATCC 14580) were exposed to ozone (0.6 ppm for 1 min and 10 min), chlorine (100 ppm for 2 min) or heat (77 ± 1°C for 5 min). One‐minute ozonation had little effect against the bacteria. There were significant differences (P < 0.05) among 10‐min ozonation, chlorine or heat inactivation of all bacteria exceptB. licheniformis. Ten‐minute ozonation caused the highest bacterial population reduction, with a mean reduction over all species of 7.3 log units followed by heat (5.4 log reduction) and chlorine (3.07 log reduction). Clean, passivated, sterile stainless steel (SS) metal coupons [2.54 × 2.54 cm2, American Society for Testing Materials (ASTM) number 304] were incubated in ultra‐high temperature (UHT) sterile milk inoculated with P. fluorescens (ATCC 948), P. fragi (ATCC 4973) and P. putida (ATCC 795) for 24–72 h. After biofilm formation, the SS metal coupons were rinsed with phosphate‐buffered saline (1 min) and exposed to ozone (0.6 ppm for 10 min) and chlorine (100 ppm for 2 min). Results indicated that both ozone and chlorine significantly reduced the biofilm bacteria adhered to the SS metal coupons as compared to the control (P < 0.05). However, there was no significant difference (P > 0.05) between ozone and chlorine inactivation of the bacteria with the exception of P. putida. Ozone killed P. putida more effectively than chlorine.

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