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PubMed2002

Microbial profile and antibiotic susceptibility of Campylobacter spp. and Salmonella spp. in broilers processed in air-chilled and immersion-chilled environments.

Carcass chilling is considered a critical step for inhibiting bacterial growth during poultry processing. The objective of this study was to compare microbiological loads and the incidence of Salmonella spp. and Campylobacter spp. on broiler carcasses subjected to immersion chilling and air chilling. Additionally, the antibiotic resistance patterns of pathogen isolates were determined. The results of this study indicated that the incidence of Salmonella spp. and Campylobacter spp. tends to be significantly lower in air-chilled broilers, suggesting that cross-contamination may be more prevalent for immersion-chilled broilers. No significant differences were detected between chilling treatments for total aerobic populations or for generic E. coli or coliform counts. Psychrotrophic populations were significantly larger (P < 0.05) in immersion-chilled broilers than in their air-chilled counterparts. Campylobacter isolates from immersion-chilled broilers had a higher incidence of resistance to nalidixic acid (NAL) and related fluoroquinolones than isolates from air-chilled broilers did. Additionally, Campylobacter isolates from air-chilled broilers had a higher frequency of resistance to tetracycline than isolates from immersion-chilled broilers did. With regard to Salmonella, isolates from immersion-chilled broilers had a higher incidence of resistance to NAL than isolates from air-chilled samples did. No Salmonella isolates from immersion- or air-chilled broilers were resistant to the fluoroquinolones tested. The chilling method used during processing may influence the microbial profile of postchilled broilers.

Adaptation, Physiological↗

PubMed2005

Persistence and differential survival of fecal indicator bacteria in subtropical waters and sediments.

Fecal coliforms and enterococci are indicator organisms used worldwide to monitor water quality. These bacteria are used in microbial source tracking (MST) studies, which attempt to assess the contribution of various host species to fecal pollution in water. Ideally, all strains of a given indicator organism (IO) would experience equal persistence (maintenance of culturable populations) in water; however, some strains may have comparatively extended persistence outside the host, while others may persist very poorly in environmental waters. Assessment of the relative contribution of host species to fecal pollution would be confounded by differential persistence of strains. Here, freshwater and saltwater mesocosms, including sediments, were inoculated with dog feces, sewage, or contaminated soil and were incubated under conditions that included natural stressors such as microbial predators, radiation, and temperature fluctuations. Persistence of IOs was measured by decay rates (change in culturable counts over time). Decay rates were influenced by IO, inoculum, water type, sediment versus water column location, and Escherichia coli strain. Fecal coliform decay rates were significantly lower than those of enterococci in freshwater but were not significantly different in saltwater. IO persistence according to mesocosm treatment followed the trend: contaminated soil > wastewater > dog feces. E. coli ribotyping demonstrated that certain strains were more persistent than others in freshwater mesocosms, and the distribution of ribotypes sampled from mesocosm waters was dissimilar from the distribution in fecal material. These results have implications for the accuracy of MST methods, modeling of microbial populations in water, and efficacy of regulatory standards for protection of water quality.

Animals↗

PubMed2006

The impact of shrimp farming effluent on bacterial communities in mangrove waters, Ceará, Brazil.

The effects of shrimp farm effluents on bacterial communities in mangroves have been infrequently reported. Classic and molecular biology methods were used to survey bacterial communities from four mangroves systems. Water temperature, salinity, pH, total heterotrophic bacteria and maximum probable numbers of Vibrio spp. were investigated. Genetic profiles of bacterial communities were also characterized by polymerase chain reaction (PCR) amplification of eubacterial and Vibrio 16S rDNA using denaturing gradient gel electrophoresis (DGGE). Highest heterotrophic counts were registered in the mangrove not directly polluted by shrimp farming. The Enterobacteriaceae and Chryseomonas luteola dominated the heterotrophic isolates. Vibrio spp. pathogenic to humans and shrimps were identified. Eubacterial genetic profiles suggest a shared community structure independent of mangrove system. Vibrio genetic profiles were mangrove specific. Neither microbial counts nor genetic profiling revealed a significant decrease in species richness associated with shrimp farm effluent. The complex nature of mangrove ecosystems and their microbial communities is discussed.

Aquaculture↗

PubMed2004

Experimental study on the safety of a new connecting device.

BACKGROUND: The tested device is a new connecting tool for infusion systems that has been designed to replace conventional single-use stopcocks. Because outbreaks of bloodstream infections have been observed during the use of similar connectors in the United States, we examined the microbiological safety of the connecting device after artificial contamination in the laboratory setting and during routine clinical use. METHODS: In the first part of the study, the new device was tested in 3 types of in vitro experiments. In the second part of the study, surgical intensive care patients had their entry ports capped with novel devices (n=27) or with conventional stopcocks (n=32), and samples of infusion fluids and swabs from entry ports were taken after completion of infusion periods. RESULTS: The new device did not perpetuate bacterial contaminations in spite of high artificial inocula in the in vitro experiments. Microbial contamination rates after 96 hours of infusion therapy for the novel connecting tool versus conventional stopcock groups were as follows: swabs from 3-way ports, 6/129 versus 1/111; rest fluid from infusion lines, 0/20 versus 1/22; rest fluid from infusion bottles, 2/196 versus 2/208; rest fluid from perfusor syringes, 7/180 versus 6/142 (all differences not significant). CONCLUSION: The novel connecting device was microbiologically safe and did not increase microbial contamination rates of intravenous infusion systems.

Catheters, Indwelling↗

PubMed2006

Use of gamma-irradiation to reduce high levels of Staphylococcus aureus on casein-whey protein coated moist beef biltong.

Moist beef biltong strips (mean moisture content = 53.6%, NaCl content = 1.91% and a(w) = 0.979) was inoculated with Staphylococcus aureus ATCC 9441 (10(6)-10(7) cfu/g), or sprayed with distilled water (non-inoculated controls). Both non-inoculated and inoculated biltong strips were coated with a casein-whey protein (1:1) edible coating followed by irradiation to a target dose of 4 kGy. S. aureus, aerobic plate, yeast and mould counts were performed to determine the effect of gamma-irradiation and the edible coating on inoculated S. aureus and the spoilage flora of the biltong. Moisture and NaCl content, a(w) and pH measurements were also performed. None of the intrinsic properties were affected to a practically significant extent. Irradiation reduced all microbial counts (P < 0.05), i.e. inoculated S. aureus (6 log cycles), aerobic plate count (5-6 log cycles) and yeast and mould counts (1-2 log cycles). Irradiation at 4 kGy is thus effective to ensure safety of moist beef biltong, and provided that initial fungal counts are not excessive, may extend the shelf-life. The edible coating had no significant effect (P > 0.05) on microbial counts, possibly because the high moisture content of the biltong diminished its oxygen barrier properties.

Animals↗

PubMed2004

Antimicrobial and antioxidative enrichment of oak (Quercus robur) bark by rotation planar extraction using ExtraChrom.

The multifunctional ExtraChrom instrument was used in the extraction of antimicrobial and radical scavenging components from oak (Quercus robur L.) bark. Milled and sieved oak bark was extracted with 80% (v/v) methanol solution in water on the ExtraChrom instrument using step-gradient in the preparative separation. Extracts were tested using agar diffusion method on Staphylococcus aureus, Enterobacter aerogenes and Candida albicans. Some extracts showed moderate bactericidal, fungicidal, bacteriostatic and fungistatic activity. The composition related to activity of the fractions and extracts was screened simultaneously by thin-layer chromatography (TLC) detected by UV and by spraying the plate with radical scavenging reagent 1,1-diphenyl-2-picrylhydrazyl (DPPH) to detect antioxidant activity. Thus, we could demonstrate the antiradical and antimicrobial activity of oak beneficial in the storage of wine against the oxidation and human microbial exposure.

Bacteria↗

PubMed2002

An emission pattern of a thermophilic bacteria attached to or imbedded in porous supports.

There are many problems with thermophilic bacteria contamination of milk in the dairy industry. This is, in part, a result of fouling by milk components on stainless steel surfaces, which provide good harboring facilities for these bacteria to attach, imbed and grow. The interactions between milk fouling and bacteria deposited in or on the fouling deposit therefore become important issues. There have been a number of previous studies on the biofilm development in dairy processing plants. Here, a different approach to investigate the bacteria emission from a porous layer has been taken. In this approach, various process fluids were flushed over the top of a model milk foulant layer that contains high percentages of milk proteins, fat and some bacteria cells, in order to investigate the behavior of the 'resident' microorganisms and how they are 'released' into the flushing liquids. Definitive results were obtained, which have created sufficient interest for a different approach taken later, where fabric layers were used as the support for the bacteria cells to explore the 'generic' behavior of the porous layer-bacteria system. This study has shown that Bacillus stearothermophilus could multiply on or within a porous layer and 'migrate' from the layer into the fluid during processing. This "migration" is somewhat peculiar in terms of its time-responses but these are reproducible in all the tests performed. The phenomena observed may have an impact on future microbial safety practice in food factories.

Animals↗

PubMed2000

Exposure to airborne fungi, MVOC and mycotoxins in biowaste-handling facilities.

Health impacts due to fungi in indoor air can only be estimated reliably, if both fungal propagules and fungal secondary metabolites are qualified and quantified. In the present study, the fungal species composition in a compost facility is compared to the spectrum of microbial metabolites in the air with regard to the physiological properties of different fungal species. A number of relevant fungi was tested for the production of both volatile and non-volatile metabolites on different substrata. The profiles of mycotoxins and microbial volatile organic compounds (MVOC) turned out to be specific for certain species in pure culture. Consequently, the fungi may have different toxicological health impacts, though information on the relevance of microbial volatiles is still limited.

Air Microbiology↗

PubMed1996

A model of host-microbial interactions in an open mammalian ecosystem.

The maintenance and significance of the complex populations of microbes present in the mammalian intestine are poorly understood. Comparison of conventionally housed and germ-free NMRI mice revealed that production of fucosylated glycoconjugates and an alpha1, 2-fucosyltransferase messenger RNA in the small-intestinal epithelium requires the normal microflora. Colonization of germ-free mice with Bacteroides thetaiotaomicron, a component of this flora, restored the fucosylation program, whereas an isogenic strain carrying a transposon insertion that disrupts its ability to use L-fucose as a carbon source did not. Simplified models such as this should aid the study of open microbial ecosystems.

Animals↗

PubMed1995

Sequential enrichment of microbial populations exhibiting enhanced biodegradation of crude oil.

The distribution of oil-degrading bacteria in the coastal water and sediments of Hokkaido, Japan, was surveyed. The potential of mixed microbial populations to degrade weathered crude oil was not confined to any ecological components (water or sediment) nor to the sampling stations. One microbial culture that was stable during repeated subculturing degraded 45% of the saturates and 20% of the aromatics present in crude oil in 10 days during the initial screening. The residual hydrocarbons in this culture were extracted by chloroform and dispersed in a fresh seawater-based medium and subsequently inoculated with microorganisms from the first culture. After full growth of the second culture, the residual hydrocarbons were again extracted and dispersed in a fresh medium in which microorganisms from the second culture had been inoculated. This sequential process was carried out six times to enrich those microorganisms that grew on the recalcitrant components of crude oil. After repeated exposure of the residual crude oil to the enriched microorganisms, about 80% of the initially added crude oil was degraded. The cultures obtained after each enrichment cycle were kept, and the degradation of fresh crude oil by the enriched microorganisms was examined. The degradative activity of the enriched cultures increased as the number of enrichment cycles increased. A microbial population that had been selected six times on the residual crude oil could degrade 70% of the saturates and 30% of the aromatics of crude oil. Thus, growth of a microbial population on residual crude oil improved its ability to biodegrade crude oil.

Bacteria↗

PubMed2002

Partial characterization of bifidobacterium breve C50 cell-free whey compounds inducing modifications to the intestinal microflora.

Cell-free whey obtained from milk fermented with Bifidobacterium breve C50 (Bb C50) has been shown to modify the intestinal flora in humans and mice. Previous work showed that no antibiotic-like or barrier effect due to overgrowing bifidobacteria was implied in the microbial modifications. The present study was focused on characterizing the compounds and mechanisms involved. Protein, sugar, and enzymatic profiles of Bb C50 whey were therefore determined and compared to those of a whey unable to modify the intestinal flora of humans and mice. No remarkable difference was noted except for a higher lactosidase activity in Bb C50 whey. Various physical treatments were then applied to fractions of Bb C50 whey. Activity was assessed in C3H mice by analyzing changes in the intestinal flora balance throughout a 15-d administration of each treated whey. Heating at 80 degrees C and aerobic storage for 2 wk completely abolished Bb C50 whey activities. In contrast, the addition of a reducing agent (cysteine hydrochloride), either at the beginning of a 15-d aerobic storage or prior to administration, as well as preserved these activities. Susceptibility to heating and oxidation suggested that an enzyme might play a role in the induced microbial changes. Since the Bb C50 lactosidase was partly inactivated by the oxidative treatment, it could support the in vivo activity. The enzyme might reach the intestinal lumen and partly degrade substrates, such as mucins, usually used by the intestinal flora. The released molecules might then favor the development of a new microbial balance.

Animals↗

PubMed2000

Comparison of different peptidase substrates for evaluation of microbial quality of aerobically stored meats.

Different aminopeptidase and endopeptidase substrates were assessed for the detection of enzymatic activity of microorganisms collected from the surface of aerobically cold-stored pork and beef. The most sensitive substrates were fluorogenic Ala-7-amino-4-methylcoumarin (Ala-AMC) or Leu-AMC and colorogenic Ala-p-nitroanilide (Ala-pNA). Activity on natural oligopeptides, e.g., bradykinin or alpha(s1) casein fragment 1 to 23, was very low. The correlation coefficient (r) between log surface counts of 66 meat samples and log fluorescence or absorbance after incubation of surface microbial cells for 2 h with Ala-AMC, Leu-AMC, and Ala-pNA was 0.89, 0.83, and 0.82, respectively. A distinct yellow color was obtained with Ala-pNA when the surface count was approximately 10(6) CFU/cm2. Although correlation and sensitivity was better, no clear advantage is obtained with the use of the fluorogenic Ala-AMC or Leu-AMC instead of Ala-pNA, a substrate proposed by Alvarado et al. (J. Food Sci. 57:1330, 1992) for rapidly assessing the microbial quality of refrigerated meat. The correlation coefficient (r) between time of cold storage and surface count was 0.69.

Aerobiosis↗

PubMed2004

Controlled release of antimicrobial compounds from highly swellable polymers.

The suitability of antimicrobial release films made from highly swellable polymers for use in food packaging was evaluated. The possibility of modulating the release kinetics of active compounds either by regulating the degree of cross-link of the polymer matrix or by using multilayer structures was addressed. The release kinetics of lysozyme, nisin, and sodium benzoate (active compounds with different molecular weights) were determined at ambient temperature (25 degrees C). The effectiveness of the proposed active films in inhibiting microbial growth was addressed by determining the antimicrobial efficiency of the released active compounds. Micrococcus lysodeikticus, Alicyclobacillus acidoterrestris, and Saccharomyces cerevisiae were used to test the antimicrobial efficiency of released lysozyme, nisin, and sodium benzoate, respectively. Results indicate that the release kinetics of both lysozyme and nisin can be modulated through the degree of cross-link of the polymer matrix, whereas multilayer structures need to be used to control the release kinetics of sodium benzoate. All the active compounds released from the investigated active films were effective in inhibiting microbial growth.

Bacillus↗

PubMed2001

Membrane bioreactor process of organic wastewater from brassylic acid manufacturing plant.

The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10,000-50,000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; (5) as the volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate COD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.

Aerobiosis↗

PubMed2003

Microbial contamination of dialysate and its prevention in haemodialysis units.

At the haemodialysis centres of nine hospitals in Japan, microbial contamination of treated water (reverse osmosis method), acid and bicarbonate concentrates, and dialysate was investigated. Among these fluids used in haemodialysis, the dialysate was most frequently contaminated and had the highest concentration of bacteria. Of 40 dialysate samples analysed, 42.5% showed a bacterial count of more than 2000cfu/mL, which was above the Association for the Advancement of Medical Instrumentation (AAMI) standard. However, among the 40 samples from 20 dialysis machines, all six dialysate samples from three dialysis machines that used an ultrafiltration membrane in the circuit before the entrance of the dialysate into the dialyser, showed a bacterial count of < or =10 cfu/mL. In addition, when an ultrafiltration membrane was used in the circuit before the entrance of the dialysate into the dialyser for four dialysis machines showing dialysate samples contaminated with 10(4)-10(5)cfu/mL the bacterial count in dialysate samples from these machines became zero. Because dialysis machines are susceptible to microbial contamination, it is necessary to take measures such as placing an ultrafiltration membrane into the circuit before the entrance of dialysate into the dialyser.

Colony Count, Microbial↗

PubMed2004

Diversity and antagonistic potential of bacteria associated with bryophytes from nutrient-poor habitats of the Baltic Sea Coast.

Very little is known about the interaction of bryophytes with bacteria. Therefore, we analyzed bacteria associated with three bryophyte species, Tortula ruralis, Aulacomnium palustre, and Sphagnum rubellum, which represent typical moss species of three nutrient-poor plant communities at the southern Baltic Sea coast in Germany. By use of two cultivation-independent techniques, denaturing gradient gel electrophoresis and single-strand conformation polymorphism analysis of the 16S ribosomal DNA, a high degree of moss specificity was found for associated bacterial communities. This specificity could be further evidenced by a cultivation-dependent approach for the following parameters: (i) plate counts of bacteria on R2A medium, (ii) proportion of antagonistic isolates, (iii) antagonistic activity as well as spectrum against pathogens, and (iv) diversity and richness of antagonistic isolates. The proportion of isolates with antagonistic activity against the pathogenic model fungus Verticillium dahliae was highest for S. rubellum (31%), followed by A. palustre (17%) and T. ruralis (5%). A high percentage (99%) of moss-associated antagonistic bacteria produced antifungal compounds. The high recovery of antagonistic isolates strongly suggests that bryophytes represent an ecological niche which harbors a diverse and hitherto largely uncharacterized microbial population with yet unknown and untapped potential biotechnological applications, e.g., for biological control of plant pathogens.

Antibiosis↗

PubMed2006

Occurrence of Streptococcus macedonicus in Italian cheeses.

A new approach for the detection and enumeration of Streptococcus macedonicus in cheese was developed. The method which is based on a first screening of cheeses by a PCR assay specific for S. macedonicus followed by plating positive samples on a differential medium (SM medium) was applied to 51 samples derived from PDO and traditional Italian cheeses. Streptococcus macedonicus was found in 16 of the 51 samples examined in the present work. With the exclusion of an Asiago cheese sample in which very high numbers of S. macedonicus (7.13 log CFU g(-1)) were found, the counts of S. macedonicus in SM medium ranged from 2.48 to 4.70 log CFU g(-1). In the same cheeses, total streptococci enumerated onto M17 agar were found at higher concentrations with values up to 7.88 log CFU g(-1). The system developed was particularly useful for the differential count of S. macedonicus in cheese and allowed to evaluate the occurrence of this species within the complex microbial lactic acid bacteria (LAB) population, which is typical of traditional cheeses. Results showed that in the examined cheeses S. macedonicus cannot be considered as a dominant LAB species.

Cheese↗

PubMed2003

Comparison of indicators of microbial quality of meat during aerobic cold storage.

This study was undertaken to evaluate various indicators for the prediction of the microbial quality of pork and beef loins during cold storage at 0 and 4 degrees C under aerobic conditions. Fresh loins of beef and pork were packaged aerobically and stored at 0 +/- 1 degrees C for 22 days and at 4 +/- 1 degrees C for 12 days or until the total plate counts (TPCs) for these loins exceeded 10(8) CFU/ml. During storage, samples were taken periodically for the measurement of TPCs, psychrotrophic bacterial counts, amine contents, volatile basic nitrogen (VBN) values, thiobarbituric acid values, D-glucose contents, L-lactate contents, pH, and electrical conductivity. Correlation coefficients were ca. 0.90 for all indicators except pH and conductivity. However, VBN and D-glucose contents showed the best correlation with bacterial counts at both temperatures for both beef and pork. Therefore, VBN and D-glucose could potentially be used as indicators in predicting the microbial quality of beef and pork during chilled storage under aerobic conditions.

Animals↗