From a global point of view, tropical rain forests occupy only 3 percent of the surface of the earth, but more than 50 percent of the biological species inhabit such areas. The development of modern biotechnology aspires to isolation of new microorganisms and improvement of their attributes, but microorganisms have been overlooked compared with plants and animals because of their microscopic life forms. Currently, more than 69,000 species in 5,100 genera of fungi, and about 3,600 species in about 700 genera of bacteria have been described in the literature. However, it is surprising to learn how small the number of microbial taxa appears in references to the application of microorganisms. Astronomical numbers of microbial strains have been isolated through the study of microbial diversity, and the attributes of a large number of strains have been improved for biotechnology. Microorganisms are not only of value for the production of useful substances; they also play unique roles in element cycles with plants and animals. Microbial strains isolated from large numbers of sources of South East Asia have been deposited with culture collections, and enriched the culture collections. Microorganisms are also significant gene pools, and these gene pools must not be lost. From this point of view, microorganisms can be regarded as the cultural heritage and the cultural property, and they must be transferred to the next generation in a normal and healthy condition. Therefore, reliable culture collections are needed as the depository and for the further study and application of the cultures.

The use of linear and non-linear models (Gompertz and logistic equations) to fit changes in microbial counts in a model system of potato homogenate at various concentrations of chemical preservatives (citric and ascorbic acids) was evaluated. The effect of undissociated acid concentrations (UAC) on mu (specific growth rate), lag phase duration and inactivation rate of Enterobacteriaceae, Lactobacillus sp, Pseudomonas sp and psychrotrophic microorganisms was determined. Citric acid had a strong inhibitory action on growth rate at low concentrations (0.065 mM UAC, pH = 5). Pseudomonas sp were the microorganisms most inhibited by citric acid. Ascorbic acid, at low UAC concentrations (0.302 mM UAC) was more inhibitory to Enterobacteriaceae than to the other microorganisms. For UAC concentration lower than 3 mM, mu values of all the microorganisms tested were higher with ascorbic acid than with citric acid; however at higher concentrations (> 10 mM) both acids had similar effects on mu.

Biofilms are described as a matrix of microorganisms which have adhered to and colonized a surface. Once formed, biofilms are difficult to remove and may be a source of contamination in food-processing environments. In this study, stainless-steel chips were fixed to surfaces adjacent to food-contact surfaces and cast-iron chips were suspended in the floor drains of four meat-processing plants. Biofilm formation was quantified by staining the attached cells and viewing them under epifluorescence microscopy. The stainless-steel and cast-iron chips removed from the plant environment showed some attached microorganisms. Floor drains appeared to provide an excellent environment for the formation of biofilms, Pseudomonas, Klebsiella, Aeromonas, and Hafnia species were identified as gram-negative microorganisms associated with the test surfaces.

The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degradation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semi-continuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichlorophenoxyacetate (400 ppm) or 2,4,6-trichlorophenol (40 to 100 ppm) were extensively degraded (70 to 100%). In short-term batch incubations, indigenous microorganisms were unable to degrade such of compounds. Degradation of 2,4,6-trichlorophenol by strain JMP134 was significantly lower at 200 to 400 ppm of compound. This strain was also able to degrade 2,4-dichlorophenoxyacetate, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-trichlorophenol when bleached Kraft mill effluent was amended with mixtures of these compounds. On the other hand, the chlorophenol concentration and the indigenous microorganisms inhibited the growth and survival of the strain in short-term incubations. In long-term (>1-month) incubations, strain JMP134 was unable to maintain a large, stable population, although extensive 2,4,6-trichlorophenol degradation was still observed. The latter is probably due to acclimation of the indigenous microorganisms to degrade 2,4,6-trichlorophenol. Acclimation was observed only in long-term, semicontinuous microcosms.

The objective of this study was to compare recovery of microorganisms for various beef samples and beef contact surfaces using conventional pour plating techniques and Petrifilm methods. Comparisons for aerobic plate count (APC), coliform count (CC), and Escherichia coli count (ECC) were done for 104 fresh or frozen retail cuts and 56 food surface or food contact surfaces. Samples were taken at a midwestern retail ground beef processing plant during a 12-month project. APC comparisons were made for pour plating using Trypticase soy agar versus Aerobic Plate Count Petrifilm. CC and ECC were compared for pour plating using violet red bile +MUG agar versus E. coli Petrifilm. Overall, paired t tests revealed a significantly higher recovery for APC from fresh and frozen beef samples using the pour plating technique (P less than or equal to 0.05). No significant differences (P > 0.05) were observed for CC from fresh and frozen meat samples. Recovery of E. coli from many beef samples was better using Petrifilm. Significantly higher ECCs were observed from fresh and frozen meat samples using Petrifilm compared to the pour plating technique (P less than or equal to 0.05). For food surfaces and food contact surfaces, a comparison between pour plating and Petrifilm was done for aerobic plate count. No significant differences (P > 0.05) in recovery could be found between methods. A comparison between neutralizing buffer and between broth for recovery of surface microorganisms was done for both the APC pour plating method and APC Petrifilm. In both cases, recovery when using between broth was significantly (P less than or equal to 0.05) higher than neutralizing buffer. Because it is convenient and gave comparative results, Petrifilm offers a good alternative for environmental microbial testing and red meat product testing.

A study was undertaken to investigate the cause of the bacteriostatic activity of fresh-cut spinach leaves against Listeria monocytogenes. L. monocytogenes was cultivated in pure tryptic soy broth for use as a monoculture, in tryptic soy broth containing 10 mg ml-1 of autoclaved or nonautoclaved freeze-dried spinach powder, and in tryptic soy broth in mixed cultures with various microorganisms isolated from fresh-cut spinach, including Pseudomonas fluorescens biovar I, P. fluorescens biovar III, Staphylococcus xylosus, and an undefined culture of mesophilic aerobic microorganisms (MAMs) isolated from freeze-dried spinach powder. These microorganisms were inoculated at 4.4 log CFU ml-1 and L. monocytogenes was inoculated at 2.4 and 4.4 log CFU ml-1. After 24 h of incubation at 30 degrees C, the populations of the two inoculum levels L. monocytogenes increased to 9.0 and 9.6 log CFU ml-1 in the tryptic soy broth control, to 5.4 and 7.5 in nonautoclaved spinach powder cultures, and to 8.8 and 9.1 log CFU ml-1 in autoclaved spinach powder cultures; In mixed cultures with biovar I of P. fluorescens, L. monocytogenes increased to 7.4 and 8.6 log CFU ml-1; with biovar III to 7.7 and 9.1, with S. xylosus to 7.8 and 9.2, and with the MAMs to 7.1 and 8.0 CFU ml-1 in the low and high listerial inoculum cultures respectively. The LSD(0.05) of the means were 0.5 and 0.6, respectively. The freeze-dried spinach powder had an inhibitory effect on the growth of L. monocytogenes. The inhibitory effect was greatly decreased when the native microorganisms were almost eliminated by heating or irradiation. These results indicate that if L. monocytogenes is present as a contaminant on fresh-cut spinach, its growth probably will be restricted by native microorganisms.

Results of the microbiological evaluation (total counts, coliforms, aerobic sporogenic bacteria, yeasts and moulds) of amaranth biscuits produced from amaranth grains irradiated by various doses of the ionizing radiation (1.5, 3 and 5 kGy) and stored six month at the room temperature (20 -25 deg C) are presented. The a sub(w) value was a supplementary parameter. Counts of microorganisms in the biscuits depended on the treatment of the grain. The share ofaerobic sporogenic microorganisms (Bacillus subtilis, B. brevis) surviving storage, especially in the samples treated with lower doses of the ionizing radiation (1.5 and 3 kGy), constituted 30 to 100 % of the total count of microorganisms. The dosage of the ionizing radiation of 5 kGy provided the maximum hygienic quality of the biscuits to the end of the 6-month storage