The microbiota of the intestinal tract of chickens plays an important role in inhibiting the establishment of intestinal pathogens. Earlier culturing and microscopic examinations indicated that only a fraction of the bacteria in the cecum of chickens could be grown in the laboratory. Therefore, a survey of cecal bacteria was done by retrieval of 16S rRNA gene sequences from DNA isolated from the cecal content and the cecal mucosa. The ribosomal gene sequences were amplified with universal primers and cloned or subjected to temporal temperature gradient gel electrophoresis (TTGE). Partial 16S rRNA gene sequences were determined from the clones and from the major bands in TTGE gels. A total of 1,656 partial 16S rRNA gene sequences were obtained and compared to sequences in the GenBank. The comparison indicated that 243 different sequences were present in the samples. Overall, sequences representing 50 phylogenetic groups or subgroups of bacteria were found, but approximately 89% of the sequences represented just four phylogenetic groups (Clostridium leptum, Sporomusa sp., Clostridium coccoides, and enterics). Sequences of members of the Bacteroides group, the Bifidobacterium infantis subgroup, and of Pseudomonas sp. each accounted for less than 2% of the total. Sequences related to those from the Escherichia sp. subgroup and from Lactobacillus, Pseudomonas, and Bifidobacterium spp. were generally between 98 and 100% identical to sequences already deposited in the GenBank. Sequences most closely related to those of the other bacteria were generally 97% or less identical to those in the databases and therefore might be from currently unknown species. TTGE and random cloning indicated that certain phylogenetic subgroups were common to all birds analyzed, but sequence data from random cloning also provided evidence for qualitative and quantitative differences among the cecal microbiota of individual birds reared under very similar conditions.

The bacterial load on the feathers (breast, thigh, and drum), skin (breast, thigh, and drum), and feet of a total of 40 broiler chickens from four different production units was characterized after the chickens were exsanguinated but before the carcasses were scalded. Each broiler carcass contained a mean of aerobic bacteria at or near 8log10/g, a level at which the carcasses would be considered spoiled. Escherichia coli counts ranged from 6.3 to 8.0 log10/g, with the highest presence on the feathers and breast skin and lower levels on the thigh and drum skin, and feet. Contamination of the carcasses followed a similar pattern for Salmonella spp., which ranged between 5.8 and 7.2 log10/g, and Campylobacter jejuni/coli which ranged between 6.1 and 7.5 log10/g. The incidence of potential pathogens was higher on the feathers, breast skin, and feet than on the thigh and drum skin. The incidence of E. coli ranged from 42.5 to 100%, Salmonella spp. ranged from 27.5 to 75%, and C. jejuni/coli ranged from 45 to 82.5%. The mean counts of microorganisms on broilers from the four different grow-out farms were significantly different (P > 0.05) from one another immediately after killing, although the magnitude of the differences was small in most cases. The means ranged from 7.3 to 8.0 log10/g for total colony-forming units (CFU), 6.7 to 7.6 log10/g for E. coli, 5.4 to 6.9 for Salmonella spp., and 5.7 to 7.9 for C. jejuni/coli. All birds were contaminated with E. coli, 60 to 100% with Salmonella spp., and 80 to 100% with C. jejuni/coli, depending on grow-out farm. C. jejuni/coli counts and incidences were higher than those of Salmonella spp., and usually lower than those of E. coli. This research demonstrates that broilers entering the processing plant are highly contaminated. Although processing seems to decrease the number and incidence of microorganisms on the carcasses, additional modifications in production, transportation, and processing are warranted to reduce the microbial population on the birds before they are slaughtered.

Saccharomyces cerevisiae ATCC 2373 and Zygosaccharomyces bailii ATCC 36947 were exposed to hydrostatic pressures ranging from 1,500 to 3,000 atmospheres for 10, 20 and 30 min in 0.1 M citrate buffer at pH 3.0, 4.0 and 5.0 at 25 and 45°C. Inactivation of inoculated yeast cultures was achieved in spaghetti sauce with meat at 25°C with 3,000 atmospheres for 10 min and also at 45°C and 2,500 atmospheres for 10 min. Viable counts were determined on potato dextrose agar (PDA) incubated at 30°C for 48 h. Pressure-induced injury was demonstrated by plate count differential between PDA and PDA supplemented with glucose (PDAG). A reduction of 7-log10 cycles colony forming units (CFU)/ml was seen for both strains at 3,000 atmospheres for 10 min at 25°C at all pH levels and at 2,250 atmospheres, pH 5.0 for 20 min at 45°C. At 2,000 atmospheres, pH 3.0 for 30 min, the increase in temperature from 25 to 45°C increased the inactivation of yeast by 6-log10 cycles. Lowering the pH from 5.0 to 3.0 enhanced lethality up to 2-log10 cycles at 2,250 atmospheres, 25°C for 30 min. Injury was most apparent at exposure parameters that produced 3- to 5-log10 cycle reductions on PDA. This was achieved (99% injury) at 2,250 atmospheres, 25°C for 30 min. These data indicate that mild heat and acidity contribute to the effectiveness of the inactivation and injury of yeast by high hydrostatic pressure (HHP).

Apium graveolens (celery) cells immobilized in coacervate capsules using alginate or carrageenan crosslinked with watersoluble chitosan demonstrated cell outgrowth, respiration rates, and total protein recoveries equal to or greater than cells immobilized in the same polymers without the chitosan shell. Amaranthin recovery from cell extracts and medium of Chenopodium rubrum cell suspensions treated with dissolved water-soluble chitosan were greater than pigment recoveries from acid soluble chitosan treated cells, and the cells demonstrated higher viability. Release from cell suspensions treated with 1,000 ug chitosan/ml medium was comparable to release from dimethylsulfoxide (DMSO)-treated suspensions. Protein release from Daucus carota suspensions treated with dissolved watersoluble chitosan demonstrated increasing release with increasing chitosan concentration, maintaining viability greater than freely suspended controls even at 1,000 ug/ml levels.

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