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Abstract The human oral cavity contains a complex microbial community that, until recently, has not been well characterized. Studies using molecular tools have begun to enumerate and quantify the species residing in various niches of the oral cavity; yet, virtually every study has revealed additional new species, and little is known about the structural dynamics of the oral microbial community or how it changes with disease. Current estimates of bacterial diversity in the oral cavity range up to 700 species, although in any single individual this number is much lower. Oral microbes are responsible for common chronic diseases and are suggested to be sentinels of systemic human diseases. Microarrays are now being used to study oral microbiota in a systematic and robust manner. Although this technology is still relatively young, improvements have been made in all aspects of the technology, including advances that provide better discrimination between perfect-match hybridizations from non-specific (and closely-related) hybridizations. This review addresses a core technology using gel-based microarrays and the initial integration of this technology into a single device needed for system-wide studies of complex microbial community structure and for the development of oral diagnostic devices.

Abstract: The U.S. Food and Drug Administration (FDA) conducted a sampling assignment in 2014 to ascertain the prevalence of Cronobacter spp. and Salmonella in the processing environment of facilities manufacturing milk powder. Cronobacter was detected in the environment of 38 (69%) of 55 facilities. The average prevalence of Cronobacter in 5,671 subsamples (i.e., swabs and sponges from different facility locations) was 4.4%. In the 38 facilities where Cronobacter was detected, the average prevalence of positive environmental subsamples was 6.25%. In 20 facilities where zone information of the sampling location was complete, Cronobacter was most frequently detected in zone 4, followed by zone 3, then zone 2, with zone 1 yielding the lowest percentage of positive samples. The prevalence of Cronobacter across the zones was statistically different (P < 0.05). There was no significant association between product type (i.e., lactose, whey products, buttermilk powder, and nonfat dried milk) and prevalence of Cronobacter in the facility. Salmonella was detected in the environment of three (5.5%) of the 55 facilities; all three facilities produced dried whey product. The overall prevalence of Salmonella in 5,714 subsamples was 0.16%. In facilities in which Salmonella was detected, the average prevalence was 2.5%. Salmonella was most frequently detected in zone 4, followed by zone 3. Salmonella was not detected in zone 1 or zone 2. The disparity between Salmonella and Cronobacter prevalence indicates that additional measures may be required to reduce or eliminate Cronobacter from the processing environment., (Published 2020 by the International Association for Food Protection. Not subject to U.S. Copyright. This is an open access article.)

The formation of botulinal toxin relative to spoilage of fresh whole tomatoes was investigated at 13 and 23°C under passively modified (MA) and controlled atmospheres (CA) and air. Tomatoes were subsurface inoculated with a composite of type A and proteolytic and nonproteolytic type B strains of Clostridium botulinum spores. Some were also inoculated with Alternaria mold spores. MA (1.0-2.9% O 2 ) was passively established by a combination of product respiration and package permeability. CA was established by placing tomatoes in continuously flushed (1% O 2 , 20% CO 2 , balance N 2 ) Plexiglass plastic containers. Tomatoes were tested for botulinum toxin by the mouse assay at the time when they first became inedible based on predefined stages of decay rather than specific storage times in order to determine the relationship between spoilage and botulinal toxigenesis. All tomatoes became inedible according to the established criteria within 17 to 46 d depending on the storage temperature and atmosphere. Botulinum toxin was not detected in the 24 composite samples of inedible tomatoes (representing 99 tomatoes) which were tested at the time they first became inedible. Toxin was detected in four of five additional composite samples (representing 10 tomatoes) which were held 2 to 9 d beyond the time they were first determined to be inedible. These data indicate that MA-packaged tomatoes can become toxic but only after becoming severely spoiled beyond the point of being organoleptically acceptable. The risk of botulism from consumption of extended shelf life whole tomatoes appears to be insignificant.

The influence of potassium sorbate on growth of Staphylococcus aureus in bacon was determined. Bacon was manufactured to contain 0 and 40 ppm sodium nitrite with 0.13 and 0.26% potassium sorbate, 40 and 120 ppm sodium nitrite, or neither nitrite nor sorbate. The bacon was inoculated with approximately 1,000 cells of a mixed suspension of five strains of Staphylococcus aureus per gram, vacuum packaged, and stored at 27 and 13 C. Bacon with 0.13 and 0.26% potassium sorbate and no nitrite was most effective in suppressing growth of S. aureus through 14 days of storage at 27 C. When stored at 13 C, bacon containing nitrite and potassium sorbate exhibited lower numbers of staphylococci after 7 days than did the bacon containing potassium sorbate alone.

Historically, nitrite has been a component of meat-curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.

Inhibition of Salmonella typhimurium and Staphylococcus aureus in Trypticase Soy Broth by the propyl ester of p-hydroxybenzoic acid (propyl paraben, 0 to 500 ppm) and butylated hydroxyanisole (BHA, 0 to 400 ppm) alone and in combination was studied. A concentration of 200 ppm of BHA was bactericidal to S. aureus , while up to 400 ppm of BHA was only restrictive to the growth of S. typhimurium . A gradual decline in viable cell numbers of S. aureus was noted with addition of 500 ppm of propylparaben while an initial reduction of S. typhimurium and subsequent growth occurred at a level of 300 ppm of propylparaben. A combination of 50 ppm of BHA-propylparaben was needed to produce a gradual reduction in viable cells of S. aureus and 150 ppm of each additive caused S. typhimurium to exhibit an apparent decrease in cell numbers and then limited growth.

Vibrio parahaemolyticus (04:K11) was grown at 35 C in trypicase soy broth containing an additional 2.5% NaCl (TSBS; pH 7.0) and in a homogenate of blue crab meat ( Callinectes sapidus ) (pH 7.0) containing various amounts of butylated hydroxylanisole (BHA). Growth in TSBS was inihibited by 50 ppm of BHA while 400 ppm BHA was required to inhibit growth in the crab meat homogenate.

Factors affecting germination of bacterial spores as well as chemical inhibition of germination are reviewed. Current theories on the nature of initiation of the germination process are also presented. Transformation of a dormant bacterial spore into a metabolically active vegetative cell involves a myriad of complex biochemical events of which the "trigger reaction" is thought to be the prime event. The ability to control or prevent this complex sequence of events from occurring by manipulation of environmental factors or use of chemical inhibitors has been the objective of numerous research endeavors. A thorough understanding of these factors is important to both maintenance and future development of an adequate, safe and wholesome food supply.

The mechanism by which potassium sorbate inhibits Bacillus cereus T and Clostridium botulinum 62A spore germination was investigated. Spores of B. cereus T were germinated at 35 degrees C in 0.08 M sodium-potassium phosphate buffers (pH 5.7 and 6.7) containing various germinants (L-alanine, L-alpha-NH2-n-butyric acid, and inosine) and potassium sorbate. Spores of C. botulinum 62A were germinated in the same buffers but with 10 mM L-lactic acid, 20 mM sodium bicarbonate, L-alanine or L-cysteine, and potassium sorbate. Spore germination was monitored by optical density measurements at 600 nm and phase-contrast microscopy. Inhibition of B. cereus T spore germination was observed when 3,900 micrograms of potassium sorbate per ml was added at various time intervals during the first 2 min of spore exposure to the pH 5.7 germination medium. C. botulinum 62A spore germination was inhibited when 5,200 micrograms of potassium sorbate per ml was added during the first 30 min of spore exposure to the pH 5.7 medium. Potassium sorbate inhibition of germination was reversible for both B. cereus T and C. botulinum 62A spores. Potassium sorbate inhibition of B. cereus T spore germination induced by L-alanine and L-alpha-NH2-n-butyric acid was shown to be competitive in nature. Potassium sorbate was also a competitive inhibitor of L-alanine- and L-cysteine-induced germination of C. botulinum 62A spores.