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1.
Typical enteric pathogens including enteroviruses, Salmonella typhi, Shigella spp., and Eschierichia coli were selected and monitored during a 1-year period in urban surface waters using the real-time polymerase chain reaction (PCR) method. By considering two routes of human exposure to urban surface waters ( i.e., drinking water and involuntary intake), and supposing that the dose–response relation may follow either an exponential model or the Beta-Poisson model, health risk assessment was conducted to estimate the safety under a given acceptable risk level upon exposure to each water and to evaluate the required level of pathogen inactivation for safeguarding human health. As a result, it was found that human health risk due to enteroviruses is often greater than that due to bacterial pathogens, and greater removal of enteroviruses would be required for safeguarding at the same acceptable risk level. 相似文献
2.
Starch industry wastewater was efficiently employed for the production of Sinorhizobium meliloti and the concentrated culture was used for the development of a biofertilizer formulation. Tween‐80 (0.02 g/L) acted as the best emulsifier for a Sinorhizobium–canola oil emulsion. The stability of the emulsion and survival of the organism was enhanced by supplementation of xanthan gum at pH 8. The refrigerated condition was most favorable for stability and survival of the microorganism. The survival of microorganism at 4±1°C was 2.78×10 10 and 2.01×10 10 CFU (colony forming unit)/mL on storage for 1 and 2 months, respectively. The values were higher than the prescribed cell count (×10 3 CFU/mL) for field application. At 40°C, the survival of bacteria reduced from 3×10 10 CFU/mL to 8.1×10 9 and 8.8×10 6 CFU/mL in 1 and 2 months, respectively. Emulsion‐coated seed was incubated at different temperatures and a cell count of 10 5 CFU/seed was observed after 2 months of storage at 4°C, which was equal to the highest level of the described requirement (10 3–10 5 CFU/seed). Emulsion supplemented with xanthan gum improved the shelf‐life under optimized conditions ( Sinorhizobium concentrate – canola oil (1:1) emulsion with 0.02 g/L Tween‐80; storage at pH 8 and temperature 4±1°C) and this emulsion with the required cell count and prolonged viability was used for the pre‐inoculation of seed or for in situ soil application. 相似文献
3.
Bacterial vaginosis can be treated by restoring the normal vaginal flora using lactobacilli. Lactobacillus crispatus KLB46 that was isolated from the human vagina has a strong antimicrobial activity and was grown in a batch and in a continuous
fermentor. During batch cultivation, the maximum specific growth rate of L. crispatus KLB 46 was 0.63 h −1 and the highest viable cell count (1.9×10 9 CFU/mL) was obtained at pH 5.5. L. crispatus KLB 46 did not grow well at either pH 3.5 or 7.5. During continuous cultivation, the highest viable cell count (1.53×10 9 CFU/mL) was obtained at a dilution rate of 0.32 h −1. However, the maximum productivity of viable cells was obtained at a dilution rate of 0.52 h −1, and was 7.33×10 11 CFU L −1 h −1, that is approximately 5 times higher than that obtained from batch culture. 相似文献
4.
Bioaerosol concentrations inside one naturally ventilated and one mechanically ventilated swine finishing barn were assessed
by sampling air using membrane filtration and impaction (six-stage Andersen sampler), and assayed by culture method. The barns,
located on the same commercial farm in northeast Kansas, did not show any significant difference (p > 0.05) in concentrations of total and respirable airborne microorganisms. The overall mean total concentrations inside the two barns
were 6.6 × 10 4 colony forming units (CFU)/m 3 (SD = 3.8 × 10 4 CFU/m 3) as measured by filtration and 8.6 × 10 4 CFU/m 3 (SD = 5.1 × 10 4 CFU/m 3) by impaction. The overall mean respirable concentrations were 9.0 × 10 3 CFU/m 3 (SD = 4.1 × 10 3 CFU/m 3) measured by filtration and 2.8 × 10 4 CFU/m 3 (SD = 2.2 × 10 4 CFU/m 3) by impaction. Total and respirable CFU concentrations measured by impaction were significantly (p < 0.05) higher than that by filtration. The persistent strains of microorganisms were various species of the following genera: Staphylococcus, Pseudomonas, Bacillus, Listeria, Enterococcus, Nocardia, Lactobacillus, and Penicillium. It appears that filtration sampling can be used for a qualitative survey of bioaerosols in swine barns while the Andersen
sampler is suitable for both quantitative and qualitative assessments.
Received: 2 April 2001 / Accepted: 13 June 2001 相似文献
5.
Old creosote-treated railway ties reused at recreational sites in Korea are potential hazards, due to the presence of harmful substances in creosote, such as polycyclic aromatic hydrocarbons (PAHs). In such sites, PAHs in ties can be leached or emitted, and human exposure might then occur. In this study, the concentrations of 16 PAHs in soil, air, and tie surfaces in old creosote-treated railway ties reused in recreational sites were investigated, and the potential health risk of the ties was evaluated through two exposure scenarios: a recreational scenario (ingestion of and dermal contact with soil and inhalation of soil particles) and a playground scenario (ingestion after contact and dermal contact with ties). For the recreational scenario, the health risks of PAHs were safe; however, for the playground scenario, the carcinogenic risk of ingestion after contact, and dermal contact with benz( a)anthracene and benzo( a)pyrene on the tie surfaces, exceeded the acceptable risk level (10 –6). For the carcinogenic risks of ingestion after contact with ties, the probabilities of cancer development were 8 and 5 in one million people for benz( a)anthracene and benzo( a)pyrene, respectively. The carcinogenic risks for dermal contact with ties were 2.4 × 10 –6 and 1.4 × 10 –6 for benz( a)anthracene and benzo( a)pyrene, respectively. 相似文献
6.
Lactobacillus paracasei was introduced as a contaminant into a multistage continuous culture ethanol fermentation system at ratios of 1:100, 1:1,
and 70:1 with Saccharomyces cerevisiae, but failed to overtake the yeast. None of the inoculation ratios allowed L. paracasei to affect S. cerevisiae in the first fermentor in the multistage system. S. cerevisiae remained constant at ∼3×10 7 CFU/ml regardless of the bacterial inoculation level, and even at the 70:1 inoculation ratio, glucose, ethanol, and lactic
acid concentrations did not change from the steady-state concentrations seen before bacterial inoculation. However, L. paracasei decreased steadily from its initial inoculation level of ∼2.2×10 9 CFU/ml and stabilized at 3.7×10 5 CFU/ml after 10 days of steady-state operation. Both organisms then persisted in the multistage system at an approximate
L. paracasei/ S. cerevisiae ratio of 1:100 which confirms that, in continuous fuel ethanol production, it would be difficult to eliminate this bacterium.
Only when the pH was controlled at 6.0 in fermentor 1 (F1) were changes seen which would affect the multistage system. Ethanol
concentration then decreased by 44% after 4 days of pH-controlled operation. This coincided with an increase in L. paracasei to >10 10 CFU/ml, and a 4× increase in lactic acid concentration to 20 g/l. When the clarified contents from other fermentors (F2–F5)
in the multistage system were used as growth media, L. paracasei was not able to grow in batch culture. This indicated that the first fermentor in the multistage system was the only fermentor
capable of supporting the growth of L. paracasei under the described conditions. Journal of Industrial Microbiology & Biotechnology (2001) 27, 39–45.
Received 26 February 2001/ Accepted in revised form 29 May 2001 相似文献
7.
Bacterial pathogen control is important in seafood production. In this study, a Cu/Co/Ni ternary nanoalloy (Cu/Co/Ni TNA) was synthesized using the oleylamine reducing method. It was found that Cu/Co/Ni TNA greatly enhanced the chemiluminescence (CL) signal of the hydroxylamine‐ O‐sulfonic acid (HOSA)–luminol system. The CL properties of Cu/Co/Ni TNA were investigated systemically. The possible CL mechanism also was intensively investigated. Based on the enhanced CL phenomenon of Cu/Co/Ni TNA, a Cu/Co/Ni TNA, penicillin, and anti‐ L. monocytogenes ( Listeria monocytogenes) antibody‐based sandwich complex assay for detection of L. monocytogenes was established. In this sandwich CL assay, penicillin was employed to capture and enrich pathogenic bacteria with penicillin‐binding proteins (PBPs) while anti‐ L. monocytogenes antibody was adopted as the specific recognition molecule to recognize L. monocytogenes. L. monocytogenes was detected sensitively based on this new Cu/Co/Ni TNA–HOSA–luminol CL system. The CL intensity was proportional to the L. monocytogenes concentration ranging from 2.0 × 10 2 CFU ml ?1 to 3.0 × 10 7 CFU ml ?1 and the limit of detection wa 70 CFU ml ?1. The reliability and potential applications of our method was verified by comparison with official methods and recovery tests in environment and food samples. 相似文献
8.
We assessed the seasonal abundance and distribution of Vibrio species as well as some selected environmental parameters in the treated effluents of two wastewater treatment plants (WWTP),
one each located in a suburban and urban community of Eastern Cape Province, South Africa. Vibrio population density ranged from 2.1×10 5 to 4.36×10 4 CFU/ml in the suburban community and from 2.80×10 5 to 1.80×10 5 CFU/ml in the urban community. Vibrio species associated with 180 μ, 60 μ, and 20 μ plankton sizes were observed at densities of 0–136×10 3 CFU/ml, 0–8.40×10 2 CFU/ml, and 0–6.80×10 2 CFU/ml, respectively at the suburban community’s WWTP. In the urban community, observed densities of culturable Vibrio were 0–2.80×10 2 CFU/ml (180 μ), 0–6.60×10 2 CFU/ml (60 μm), and 0–1.80× 10 3 CFU/ml (20 μm). The abundance of free-living Vibrio species ranged from 0 to 1.0×10 2 and 1.0×10 3 CFU/ml in the suburban and urban communities’ WWTPs, respectively. Molecular confirmation of the presumptive Vibrio isolates revealed the presence of V. fluvialis (41.38%), V. vulnificus (34.48%), and V. parahaemolyticus (24.14%) in the suburban community effluents. In the urban community molecular confirmation revealed that the same species
were present at slightly different percentages, V. fluvialis (40%), V. vulnificus (36%), and V. parahaemolyticus (24%). There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, but Vibrio species abundance was positively correlated with temperature ( r=0.565; p<0.01), salinity, and dissolved oxygen ( p<0.05). Turbidity and pH showed significant seasonal variation ( p<0.05) across the seasons in both locations. This study underscores the potential of WWTPs to be sources of Vibrio pathogens in the watershed of suburban and urban communities in South Africa. 相似文献
9.
A limit of detection of 200 CFU/mL of Salmonella typhi spiked in various sample matrices were achieved in 30 min. The sample matrices were raw/unprocessed milk, commercially available milk, juice from packed bottles, fresh juice from carts, potable water, turbid water and calf serum. The complete protocol comprised of three steps: (a) cell lysis (b) nucleic acid amplification and (c) an in situ optical detection. The cell lysis was carried out using a simple heating based protocol, while the loop-mediated isothermal amplification of DNA was carried out by an in-house designed and fabricated system. The developed system consists of an aluminum block fitted with two cartridge heaters along with a thermocouple. The system was coupled to a light source and spectrometer for a simultaneous in situ detection. Primers specific for STY2879 gene were used to amplify the nucleic acid sequence, isolated from S. typhi cells. The protocol involves 15 min of cell lysis and DNA isolation followed by 15 min for isothermal amplification and simultaneous detection. No cross-reactivity of the primers were observed at 10 6 CFU/mL of Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Salmonella paratyphi A, Pseudomonas aeruginosa, Bacillus cereus, Lysteria monocytogenes, Clostridium botulinum, Staphylococcus aureus and Salmonella havana. In addition, the system was able to detect S. typhi of 200 CFU/mL in a concoction of 10 6 CFU/mL of E. coli, 10 6 CFU/mL of V. cholerae, and 10 6 CFU/mL of hepatocyte-derived cellular carcinoma HUH7 cells. The proposed rapid diagnostic system shows a promising future in the field of food and medical diagnostics. 相似文献
10.
The protective efficacy of and immune response to heat‐killed cells of monovalent and hexavalent mixtures of six serogroups/serotypes of Shigella strains ( Shigella dysenteriae 1, Shigella flexneri 2a, S. flexneri 3a, S. flexneri 6, Shigella boydii 4, and Shigella sonnei) were examined in a guinea pig colitis model. A monovalent or hexavalent mixture containing 1 × 10 7 of each serogroup/serotype of heat‐killed Shigella cells was administered orally on Days 0, 7, 14 and 21. On Day 28, the immunized animals were challenged rectally with 1 × 10 9 live virulent cells of each of the six Shigella serogroups/serotypes. In all immunized groups, significant levels of protection were observed after these challenges. The serum titers of IgG and IgA against the lipopolysaccharide of each of the six Shigella serogroups/serotypes increased exponential during the course of immunization. High IgA titers against the lipopolysaccharide of each of the six Shigella serogroups/serotypes were also observed in intestinal lavage fluid from all immunized animals. These data indicate that a hexavalent mixture of heat‐killed cells of the six Shigella serogroups/serotypes studied would be a possible broad‐spectrum candidate vaccine against shigellosis. 相似文献
11.
Ultraviolet (UV) irradiation has high potential to inactivate a wide range of biologic agents and is one of several nonadditive
technologies being studied. The photoinactivation property of pulsed UV laser radiation (at wavelengths of 355 and 266 nm),
used as an effective physical means to inactivate two typical microorganisms, prokaryotic ( Escherichia coli K12) and eukaryotic ( Saccharomyces cerevisiae), with respect to dose and exposure times, was examined. An E. coli population of 1.6 × 10 4 colony-forming units (CFU)/ml was inactivated with a dose of 16.7 J/cm 2 energy at 355-nm wavelength. However, E. coli cells at higher concentrations were inactivated by only 98% using the same dose. Interestingly, an E. coli population of 2 × 10 7 CFU/ml was completely inactivated using only 0.42 J/cm 2 at 266-nm wavelength ( P ≤ 0.05). With respect to S. cerevisiae, the results were similar to those of E. coli irradiation considering that S. cerevisiae is 100 times larger than E. coli. A dose of 16.7 J/cm 2 completely inactivated an S. cerevisiae population of 6 × 10 3 CFU/ml at 355-nm wavelength. Exposure to 266-nm wavelength, with energy doses of 1.67, 0.835, and 0.167 J/cm 2, successfully inactivated S. cerevisiae populations of 3 × 10 6, 1.4 × 10 5, and 1.5 × 10 4 CFU/ml, respectively ( P ≤ 0.05). In conclusion, compared with 355-nm wavelength, a pulsed UV laser at 266-nm wavelength inactivated a high titer
of bacterial and yeast indicator standards suspended in phosphate-buffered saline-A. 相似文献
12.
Biofilms are a major source of human pathogenic Legionella pneumophila in aquatic systems. In this study, we investigated the capacity of L. pneumophila to colonize floating biofilms and the impact of Acanthamoeba castellanii on the replication of biofilm-associated Legionella. Biofilms were grown in Petri dishes and consisted of Aeromonas hydrophila, Escherichia coli, Flavobacterium breve, and Pseudomonas aeruginosa. Six hours following inoculation, Legionella were detected in floating biofilms in mean concentrations of 1.4 × 10 4 cells/cm 2 (real-time polymerase chain reaction) and 8.3 × 10 2 CFU/cm 2 (culture). Two-way analysis of variance tests and fluorescent in situ hybridization clearly proved that increased biofilm-associated L. pneumophila concentrations were the result of intracellular replication in A. castellanii. Forty-eight hours after the introduction of A. castellanii in the Petri dishes, 90 ± 0.8% of the amoebae (infection rate) were completely filled with highly metabolic active L. pneumophila (mean infection intensity). 相似文献
13.
A rapid and sensitive 8-h PCR assay has been developed for detection of Salmonella serovars in seafood. A total of 110 fresh and raw seafood samples were analysed for the presence of Salmonella using different enrichment periods prior to PCR assay. Seafood samples included in this study were fish, shrimps, mussels,
crabs, edible oysters, and clams, collected from local fish markets in Cochin (India). The assay was performed with a Salmonella-specific 284 bp invA gene amplicon. Specificity and sensitivity of the assay were ascertained with seafoods spiked with viable Salmonella cells to a level of 10 6 to 2 CFU per 25 g. Detection efficiency of the assay increased with increasing enrichment period for seafood, and 33.6% of
seafood samples were found positive for Salmonella by 8-h PCR assay . Detection limit for the 8-h PCR assay showed visible 284 bp amplicon from seafood homogenates spiked with 2 CFU per 25 g.
Seafood samples spiked with different Salmonella serovars, namely Salmonella typhi, Salmonella typhimurium, Salmonella enteritidis, Salmonella mbandka, Salmonella bareilly, and Salmonella weltevreden, were detected, confirming this technique would be ideal for detection of the Salmonella serovars prevalent in seafood. This study also covered inhibition by the seafood matrix and the detection limit for dead
Salmonella cells during the PCR assay. There was no visible inhibition of this Salmonella PCR assay by seafood matrices. The detection limit for dead Salmonella cells by 8-h PCR assay was 2 × 10 3 CFU per 25 g seafood. The data indicated that dead cells of Salmonella in naturally contaminated seafood samples do not interfere with the assay resulting in false positives. 相似文献
14.
Aims: To evaluate throughput of seeded Legionella pneumophila bacteria in domestic point‐of‐use filters. Methods and Results: The filters were challenged with tap water seeded with Leg. pneumophila. After multiple challenge events (4·25 × 10 11 CFU per filter), the levels of Legionella were lower in the effluent from the filter containing both copper and silver (mean 4·48 × 10 3 CFU ml ?1) than in the effluent from the filter containing copper only (1·26 × 10 4 CFU ml ?1; P < 0·001). After a single challenge event of approx. 5 × 10 9 CFU L. pneumophila per filter, there was no significant difference between the levels of Legionella in the effluents from a carbon filter containing copper and a carbon filter with no metals (mean 6·87 × 10 2 and 6·89 × 10 2 CFU ml ?1, respectively; P = 0·985). Conclusions: Legionella was detected in filter effluent up to 6 weeks after being challenged, indicating that while filters may reduce the levels during an initial contamination event, the exposure is extended as the accumulated bacteria slough off over time. Significance and Impact of the Study: This study has provided an understanding of the response of Legionella to the use of silver and copper in domestic point‐of‐use carbon filters. 相似文献
15.
Skin mucosal lymphoid tissues of fish are the first line of defence against pathogen invasion. We investigated the effects of Lactiplantibacillus plantarum subsp. plantarum L7, singularly or in combination with Limosilactobacillus reuteri P16, on mucosal immunity and diseases resistance of carp Cyprinus carpio. C. carpio (average weight: 26.28 ± 1.02 g) were divided into five experimental groups. Fish in each group were fed with one of the following potential probiotic-supplemented diets: control (0 – basal diet), D1 (107 CFU/g L7), D2 (108 CFU/g L7), D3 (109 CFU/g L7), and D4 (108 CFU/g L7 + 108 CFU/g P16). Eight weeks post-feeding, growth performance was higher in D4, with a final weight gain of 67.18 ± 1.47 g. Results showed a significantly higher skin mucosal lysozyme, alkaline phosphatase, mucus protein level, superoxide dismutase, and catalase activities in D2 and D4 compared to the control. However, potential probiotics had no significant effect on skin mucosal immunoglobulin level. Skin mucus of D4 exhibited stronger inhibition zones against pathogenic bacterial strains. Moreover, digestive enzyme activities (protease, lipase) were highest in D4. Intesinal lactic acid bacterial counts of fish fed combind probiotics (i.e. D4) was significantly higher than the control. Further, supplementation of potential probiotics altered the expression of IL-1β, TNF-α, and IL-10 cytokines. Fish from D4 exhibited significantly higher relative post-challenge survival (69.7%) against Aeromonas hydrophila, followed by D2 (66.67%). Therefore, the inclusion of L. plantarum subsp. plantarum L7 at 108 CFU/g or in combination with L. reuteri P16 could enhance the growth performance, mucosal immune responses, and disease resistance of C. carpio. 相似文献
16.
Populations of Xanthomonas axonopodis pv. manihotis and X. axonopodis pv. vignicola, causal agents of cassava and cowpea bacterial blight, respectively, were quantified in insects. The pathogens were found in the faeces, the intestines, and on the legs and mandibles of Zonocerusvariegatus. Additionally, X. axonopodis pv. manihotis was localized in the insect gut by immunofluorescence microscopy. Xanthomonas axonopodis pv. manihotis survived at least 1 week in the insect intestines and at least 5 weeks in faeces kept under controlled conditions, while survival in faeces exposed to sunlight was <2 weeks. Five percentage [e.g. 5.8 × 10 7 colony‐forming units (CFU)/g faeces] of the fed population of X. axonopodis pv. manihotis in cassava leaves were recovered viable in the faeces after passage through the insect. The transmission of cassava bacterial blight by pathogen‐contaminated insect faeces to intact, healthy cassava leaves was demonstrated for the first time. Xanthomonas axonopodis pv. vignicola was isolated from organs and faeces of the grasshopper Pyrgomorpha cognata, the Senegalese grasshopper ( Oedaleus senegalensis), bee ( Apis mellifera) and three Coleoptera ( Ootheca mutabilis, Mylabris spp., Exochomus troberti) collected in bacterial blight‐infected cowpea fields. Cowpea belonged to the diet of 19 grasshopper species collected in cowpea fields as demonstrated by residues in their faeces. Pathogen‐contaminated Z. variegatus initiated an epiphytic population of 8.9 × 10 4 CFU/g on healthy cowpea leaves. Spraying cassava and cowpea leaves with 10 2 and 10 4 CFU/ml of their respective pathogen was sufficient to evoke symptoms. A possible role of insects in the transmission of X. axonopodis pvs. vignicola and manihotis is discussed. 相似文献
17.
This study investigates the exposure of workers to biological particles in a poultry litter burning plant in operation. The
microorganism concentrations were examined at different workplaces during procedures leading to increased emissions. The concentrations
of culturable airborne mesophilic, xerophilic and thermophilic microorganisms in the ambient air were tested inside and outside
of the burning plant using two different methods of measuring. The focus of this study was on the quantitative evaluation
of culturable bacteria as well as the quantitative and qualitative evaluation of gram-negative bacteria, fungi and thermophilic
actinomycetes. The maximum airborne concentrations were found in the delivery hall. Mesophilic bacteria concentrations reached
up to 1.7 × 10 6 CFU/m 3; gram-negative bacteria up to 9.1 × 10 2 CFU/m 3. Fungal propagule concentrations for xerophilic fungi were between 1.2 × 10 3 and 2.9 × 10 4 CFU/m 3 and for mesophilic fungi between 4.4 × 10 2 and 2.9 × 10 4 CFU/m 3. Among fungi, Aspergillus niger, Eurotium herbariorum and Scopulariopsis brevicaulis species were dominant. Thermophilic actinomycetes reached airborne concentrations of 8.7 × 10 4 CFU/m 3, with increased concentrations of the pathogens causing extrinsic allergic alveolitis. The high concentrations of airborne
microorganisms in poultry litter burning plants and the potential hazard of the intake of microorganisms including potential
pathogens require the introduction of consistent measures in both technical areas and personnel management. 相似文献
18.
The ability of isolates of Paenibacillus spp. to protect Brassica oleracea var. capitata (cabbage) against the black rot pathogen, Xanthomonas campestris pv. campestris ( Xcc),was evaluated. Twenty-four isolates of Paenibacillus spp., isolated from New Zealand-grown brassica hosts or soil, were evaluated for in vitro antagonism towards six Xcc isolates. Seven Paenibacillus spp. isolates with different levels of in vitro suppressive activity against Xcc were screened in pot experiments for their capacity to reduce black rot symptoms on cabbage. Two Paenibacillus isolates (P10 and P16) exhibited biocontrol activity against Xcc, and four isolates (P1, P6, P9, and P24) reduced cabbage seed germination and seedling emergence. The dependence of bioactivity on inoculum rate was investigated with three Paenibacillus isolates (P6, P10, and P16) at three different concentrations (5?×?10 8, 5?×?10 9, and 5?×?10 10?CFU?ml ?1). Negative effects on seedling emergence were detected with isolate P6 at concentrations?≥5?×?10 9?CFU?ml ?1. All three isolates applied at the three concentrations reduced black rot symptoms on the cotyledons and true leaves. There was poor or no relationship between the inhibitory effect of Paenibacillus spp . isolates on the growth of Xcc in vitro, and their biocontrol activity in vivo. Paenibacillus isolate P16 was identified as a potential biological control of black rot in cabbage. 相似文献
19.
Inhalation of airborne microorganisms and organic dust is an occupational concern among workers in agricultural industries.
Airborne microorganisms and particulate matter samples were collected from poultry house, flourmill, textile, and food industry
sites by use of liquid impinger and gravimetric samplers. Particulate matter concentrations were recorded at median concentrations
of 1.56, 1.92, 4.39, and 0.7 mg/m 3 in the occupied poultry house, textile, flourmill, and food indoor working environments, respectively. The highest median
particulate matter concentration (27.9 mg/m 3) was detected at the flourmill’s stack site. The highest median indoor concentration of culturable airborne bacteria (6.23 × 10 5 CFU/m 3) was found at the occupied poultry-house site and the lowest concentration (4.6 × 10 3 CFU/m 3) was found at the food industry site. The highest median indoor concentration of culturable airborne fungi (3.15 × 10 4 CFU/m 3) was found at the flourmill site whereas the lowest (1.24 × 10 3 CFU/m 3) was found at the textile industry site. Bacillus and Staphylococcus were the predominant Gram-positive bacteria whereas Acinetobacter and Klebsiella were the predominant Gram-negative bacteria. Escherichia coli and Salmonella were only detected in the indoor air at the poultry house site. Aspergillus
flavus, Aspergillus niger, Penicillium, and yeast were the predominant fungal types at flourmill, textile, food industry, and poultry house, respectively. Workers
were continuously exposed to airborne microorganisms at a median value of 10 4 CFU/m 3 in all the industries studied. 相似文献
20.
Quantitative and qualitative studies of the bacterial flora of farmed freshwater prawn ( Macrobrachium rosenbergii) larvae in Saudi Arabia were performed, and isolates identified where possible. Physico‐chemical characteristics, bacterial counts, and the nature of the bacterial flora of larvae rearing tank water, sediment, tank wall surfaces, larval surface, supplied water, and feed were investigated. Bacterial counts ranged from 2.1 ± 1.3 × 10 5 to 2.2 ± 0.8 × 10 7 colony forming units (CFU) ml ?1 in tank water; 4.4 ± 0.9 × 10 7 to 8.3 ± 1.7 ×10 9 CFU g ?1 in tank sediment; 8.6 ± 1.0 × 10 2 to 9.8 ±0.7 × 10 4 CFU cm ?2 on the tank wall surface; 1.3 ± 1.1 × 10 4 to 7.7 ± 1.6 × 10 6 CFU per larva surface, 7.9 ± 1.2 × 10 5 to 5.0 ± 1.5 × 10 7 CFU g ?1 in washed larval tissue slurries, 9.1 ± 0.7 × 10 3 CFU ml ?1 in supplied water, and 2.4 ± 1.9 ×10 10 CFU g ?1 in mixed feed. Fourteen bacterial genera were identified, including Chryseomonas sp., Vibrio spp., Cellulomonas sp., Aeromonas hydrophila, and Pasteurella sp. The tank water and sediment had similar bacteria to those on the prawn larvae. Chryseomonas sp., Cellulomonas sp. and Vibrio sp. were the most dominant species (prevalence >10%) in tank water; Chryseomonas sp., Pseudomonas alcaligenes and Shewanella putrefaciens in the sediment; Ps. alcaligenes and Cellulomonas sp. on the tank wall surface; Chryseomonas sp., and Cellulomonas sp. on the larval surface; and Chryseomonas sp., Vibrio vulnificus, Sh. putrefaciens and V. alginolyticus in the washed larval tissue slurries (prevalence 10%). Pseudomonas alcaligenes, Moraxella sp., Serratia liquefaciens, Gordona sp. and Burkholderia glumae were absent in larvae but identified in the culture water, tank sediment, and tank wall surface. Pseudomonas sp., Chryseomonas sp., Pasteurella sp. and V. alginolyticus were the prevalent bacteria (>12%) in supplied water. The feed contained V. alginolyticus, A. hydrophila and Cellulomonas sp. as the dominant bacteria (>13%). In the culture water and larvae samples, 83% of the feed and supplied water bacteria were identified. 相似文献
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