Levels of bacteria, fungi, and endotoxin in bulk and aerosolized corn silage

Three samples of silage taken from the surface of a silo and from depths of 20 and 45 cm in the silo were studied for identification of the potential agents causing symptoms of organic dust toxic syndrome. The samples were examined by dilution plating before and after aerosolization in an acoustical dust generator. Aerosol samples were collected by liquid impinger and filter cassettes. The samples were examined for total aerobic bacteria, anaerobic bacteria, gram-negative bacteria, lactobacilli, listeriae, thermophilic actinomycetes, fungi, and endotoxin. Very high levels of total aerobic bacteria and fungi were found in the surface sample (up to 10(9) CFU/g in the bulk sample and up to 10(9) CFU/m3 after aerosolization), whereas the corresponding values from the deepest site were 100 to 50,000 times lower. Aspergillus fumigatus predominated among the fungi, whereas Bacillus and gram-negative organisms (Pseudomonas, Alcaligenes, Citrobacter, and Klebsiella species) prevailed among bacteria. Thermophilic actinomycetes occurred in numbers up to 10(7) CFU/g in the bulk samples, whereas anaerobic bacteria, lactobacilli, and listeriae were only few or absent. The concentration of endotoxin was high in the surface sample (up to 211.4 Endotoxin Units/mg) and about 200-fold lower in the sample from the deepest site. The results show that contact with dust from the surface of silage carries the risk of exposure to high concentrations of microorganisms, of which A. fumigatus and endotoxin-producing bacteria are the most probable disease agents.     

样品磷化氢含量与某些微生物群落及酶活的关系

探讨了样品中磷化氢含量与不同微生物群落及几种酶活性的关系。结果表明,样品的磷化氢含量与厌氧微生物总量、有机磷细菌、反硝化细菌、碱性磷酸酶活性及脱氢酶活性呈显著的正相关关系,其相关系数(R2)分别达到了0.93,0.90,0.69,0.79和0.82;而与好氧异养微生物总量、无机磷细菌、硫酸盐还原菌、酸性磷酸酶的关系不大。此结果说明,相关类群的微生物在磷化氢的产生中可能起重要的作用。     

Levels of bacteria, fungi, and endotoxin in bulk and aerosolized corn silage.

Three samples of silage taken from the surface of a silo and from depths of 20 and 45 cm in the silo were studied for identification of the potential agents causing symptoms of organic dust toxic syndrome. The samples were examined by dilution plating before and after aerosolization in an acoustical dust generator. Aerosol samples were collected by liquid impinger and filter cassettes. The samples were examined for total aerobic bacteria, anaerobic bacteria, gram-negative bacteria, lactobacilli, listeriae, thermophilic actinomycetes, fungi, and endotoxin. Very high levels of total aerobic bacteria and fungi were found in the surface sample (up to 10(9) CFU/g in the bulk sample and up to 10(9) CFU/m3 after aerosolization), whereas the corresponding values from the deepest site were 100 to 50,000 times lower. Aspergillus fumigatus predominated among the fungi, whereas Bacillus and gram-negative organisms (Pseudomonas, Alcaligenes, Citrobacter, and Klebsiella species) prevailed among bacteria. Thermophilic actinomycetes occurred in numbers up to 10(7) CFU/g in the bulk samples, whereas anaerobic bacteria, lactobacilli, and listeriae were only few or absent. The concentration of endotoxin was high in the surface sample (up to 211.4 Endotoxin Units/mg) and about 200-fold lower in the sample from the deepest site. The results show that contact with dust from the surface of silage carries the risk of exposure to high concentrations of microorganisms, of which A. fumigatus and endotoxin-producing bacteria are the most probable disease agents.     

Microbial populations in wetwood of European white fir (Abies alba Mill.)

Abstract A method for extraction of microbial populations from wood samples was worked out which gave good recovery of both aerobic and anaerobic microorganisms in agar shake dilution and plating enumerations. This method was applied to the quantification of microbial populations in three European white firs ( Abies alba Mill.) which were afflicted with the European fir disease. Low numbers of aerobic microorganisms (10²−10⁴ colony- forming units (cfu) per g fresh tissue) were detected in sapwood irrespective of the degree of affliction. Anaerobic bacteria were usually 1–2 orders of magnitude less frequent. Wetwood of highly diseased firs contained significantly higher numbers of aerobic microorganisms (10⁵−10⁷), whereas the number of anaerobes was not enhanced significantly. Among the prevalent aerobic microorganisms in wetwood were Protaminobacter, Pseudomonas strains, and a yeast. In anaerobic counts from wetwood, Klebsiella and Vibrio strains predominated. The sapwood contained Bacillus, Beijerinckia, Staphylococcus , and Clostridium spp. High numbers of aerobic microorganisms were also detected in the roots and lower stem of a diseased vine plant ( Vitis vinifera L.). The importance of microbial populations in wetwood formation and disease expression is discussed.     

Geomicrobiology of high-level nuclear waste-contaminated vadose sediments at the hanford site, washington state

Sediments from a high-level nuclear waste plume were collected as part of investigations to evaluate the potential fate and migration of contaminants in the subsurface. The plume originated from a leak that occurred in 1962 from a waste tank consisting of high concentrations of alkali, nitrate, aluminate, Cr(VI), (137)Cs, and (99)Tc. Investigations were initiated to determine the distribution of viable microorganisms in the vadose sediment samples, probe the phylogeny of cultivated and uncultivated members, and evaluate the ability of the cultivated organisms to survive acute doses of ionizing radiation. The populations of viable aerobic heterotrophic bacteria were generally low, from below detection to approximately 10(4) CFU g(-1), but viable microorganisms were recovered from 11 of 16 samples, including several of the most radioactive ones (e.g., >10 microCi of (137)Cs/g). The isolates from the contaminated sediments and clone libraries from sediment DNA extracts were dominated by members related to known gram-positive bacteria. Gram-positive bacteria most closely related to Arthrobacter species were the most common isolates among all samples, but other phyla high in G+C content were also represented, including Rhodococcus and Nocardia. Two isolates from the second-most radioactive sample (>20 microCi of (137)Cs g(-1)) were closely related to Deinococcus radiodurans and were able to survive acute doses of ionizing radiation approaching 20 kGy. Many of the gram-positive isolates were resistant to lower levels of gamma radiation. These results demonstrate that gram-positive bacteria, predominantly from phyla high in G+C content, are indigenous to Hanford vadose sediments and that some are effective at surviving the extreme physical and chemical stress associated with radioactive waste.     

Aerobic and anaerobic microorganisms in tubercles of the Columbus, Ohio, water distribution system.

Aerobic and anaerobic microorganisms were enumerated in tubercles collected from sections of the water distribution pipeline in the Columbus, Ohio, metropolitan area. Coliform bacteria were not detected in the tubercles examined. Sulfate-reducing bacteria were detected in 80% of the samples. Nitrate-reducing heterotrophs were present in all samples. The results, including plate counts of aerobic heterotrophs, indicated variation in bacterial densities depending on the tubercle sample and fraction examined. The associations among the viable counts obtained by the different culture methods were analyzed statistically, using three methods (Pearson, Spearman, and Kendall).     

Analysis of the differences in microbial community structures between suspended and sessile microorganisms in rivers based on quinone profile

In this study, a quinone profiling method was applied to clarify the differences in community structure between suspended and sessile microorganisms in rivers. The compositions of microbial quinone of 6 sites for 4 rivers were analyzed. Ubiquinone (UQ)-8, UQ-10, menaquinone (MK)-7, and plastoquinone (PQ)-9 were observed in all samples of suspended and sessile microorganisms for the sites investigated. The dominant quinone species in suspended microorganisms was ubiquinone, and that in sessile microorganism was photosynthetic quinones (namely PQ-9 and vitamin K1). This indicated that aerobic bacteria were abundant in the suspended microorganisms, and photosynthetic microorganisms such as micro-algae and cyanobacteria dominated in the sessile microorganisms. The quinone concentration in the river waters tested, which reflects the concentration of suspended microorganisms, ranged from 0.045 to 1.813 nmol/L. The microbial diversities of suspended and sessile microorganisms calculated based on the composition of all quinones were in the range from 3.4 to 7.5, which was lower than those for activated sludge and soils. Moreover, the diversity of heterotrophic bacteria for sessile microorganisms in the rivers was higher than that for the suspended microorganisms.     

微生物嗜铁素介导的铁摄取

嗜铁素是好氧菌和兼性厌氧菌的一种产物,它是微生物在低铁条件下产生的小分子的、特异性的Fe^3＋螯合因子。大多数的好氧和兼性厌氧微生物至少合成一种嗜铁素,由嗜铁素介导的铁摄取可能是细菌最普遍的一种获取铁元素的方式。     

Fate of Cryptosporidium oocysts, Giardia cysts, and microbial indicators during wastewater treatment and anaerobic sludge digestion.

The extent of reduction in selected microorganisms was tested during both aerobic wastewater treatment and anaerobic digestion of sludge at the wastewater treatment plant in Ottawa to compare the removal of two encysted pathogenic protozoa with that of microbial indicators. Samples collected included the raw wastewater, the primary effluent, the treated wastewater, the mixed sludge, the decanted liquor, and the cake. All of the raw sewage samples were positive for Cryptosporidium oocysts and Giardia cysts, as well as for the other microorganisms tested. During aerobic wastewater treatment (excluding the anaerobic sludge digestion), Cryptosporidium and Giardia were reduced by 2.96 log10 and 1.40 log10, respectively. Clostridium perfringens spores, Clostridium perfringens total counts, somatic coliphages, and heterotrophic bacteria were reduced by approximately 0.89 log10, 0.96 log10, 1.58 log10, and 2.02 log10, respectively. All of the other microorganisms were reduced by at least 3.53 log10. Sludge samples from the plant were found to contain variable densities of microorganisms. Variability in microbial concentrations was sometimes great between samples, stressing the importance of collecting a large number of samples over a long period of time. In all cases, the bacterial concentrations in the cake (dewatered biosolids) samples were high even if reductions in numbers were observed with some bacteria. During anaerobic sludge digestion, no statistically significant reduction was observed for Clostridium perfringens, Enterococcus sp., Cryptosporidium oocysts, and Giardia cysts. A 1-2 log10 reduction was observed with fecal coliforms and heterotrophic bacteria. However, the method utilized to detect the protozoan parasites does not differentiate between viable and nonviable organisms. On the other hand, total coliforms and somatic coliphages were reduced by 0.35 log10 and 0.09 log10, respectively. These results demonstrate the relative persistence of the protozoa in sewage sludge during wastewater treatment.     

胆道手术患者胆汁的菌群分析

本文对59例胆道手术患者的胆汁标本进行了菌群分析。共检出各类细菌156株,其中厌氧菌70株,以类杆菌最为常见(44株);兼性需氧菌86株,以大肠杆菌最为常见(37株)。胆汁细菌培养阳性率为86.4％(51/59);64.4％(38/59)的标本为厌氧菌与兼性厌氧菌混合污染。22.0％(13/59)的标本中仅分离到兼性需氧菌。提示,胆汁中污染的类杆菌及大肠杆菌是胆道手术后感染的主要原因菌。     

除草剂二氯喹啉酸对水稻田土壤中微生物种群的影响

对好氧微生物采用平板稀释法,厌氧微生物采用最大或然计数法和滚管法研究土壤中施入0．33、0．67、1．00、1．33、2．00μg·g^-1干土除草剂二氯喹啉酸后对土壤可培养微生物种群数量的影响。结果表明,各种微生物对二氯喹啉酸的反应随其施加浓度的不同而有差异．二氯喹啉酸对水稻田土壤中好氧性细菌、水解发酵细菌、反硝化细菌数量的影响都是短暂的,第33d时均能恢复至接近对照水平,浓度在1．33μg·g^-1干土以下时二氯喹啉酸促进真菌数量增加,高于该浓度时则具有抑制作用．施用各浓度二氯喹啉酸初期,对土壤中放线菌和产甲烷菌有一定程度的抑制效应,但低浓度时抑制效应在培养后期消失．正常土壤施用量的二氯喹啉酸(即0．67μg·g^-1干土)对水田土壤微生物各种群无实质危害级农药。     

Microbiologic analysis of results from blood cultures

The aim of our investigations was the microbiological analysis together with the evaluation of sensitivity of bacteria frequently isolated from blood cultures. Blood samples were taken from patients with symptoms suggesting bacteremia in Rydygier's Hospital in Cracow. A total of 11,170 blood samples taken from 1997 to 2000 were tested. Automatic VITAL system (bioMerieux) was applied to culture and detect microorganisms. Bacteria were identified by ATB system (bioMerieux). Susceptibility was detected by ATB and disc diffusion method. Percentage of positive results relating to detection of microorganisms of clinical significance was 16.9% (1891 cultures). Staphylococcus spp. (Staph. epidermidis in range 22.8% to 21.9%), Enterococcus spp. and Streptococcus spp. were most frequently isolated species among aerobic Gram-positive bacteria. In 2000, compared to 1997 the number of isolates of MRSA increased considerably (from 1.8% to 6.8%). In blood infections the increase of frequency of E. coli bacteria was also noted: 6.1% and 11.4% in 1997 and 2000, respectively. Among non-fermentant bacilli the percentage of occurrence of P. aeruginosa in the period of 4 years was comparable in the range 7.3% in 1997 to 7.2% in 2000. The increase in the frequency of blood infections of A. baumanii was also noticed (respectively from 4.8% to 9.9%). Susceptibility of P. aeruginosa strains to selected beta-lactame antibiotics and aminoglycosydes increased in 2000 in comparison to 1999. A. baumanii strains were 100% sensitive only to imipenem.     

Indigenous and contaminant microbes in ultradeep mines

Rock, air and service water samples were collected for microbial analyses from 3.2 kilometres depth in a working Au mine in the Witwatersrand basin, South Africa. The approximately metre-wide mined zone was comprised of a carbonaceous, quartz, sulphide, uraninite and Au bearing layer, called the Carbon Leader, sandwiched by quartzite and conglomerate. The microbial community in the service water was dominated by mesophilic aerobic and anaerobic, alpha-, beta- and gamma-Proteobacteria with a total biomass concentration approximately 10(4) cells ml(-1), whereas, that of the mine air was dominated by members of the Chlorobi and Bacteroidetes groups and a fungal component. The microorganisms in the Carbon Leader were predominantly mesophilic, aerobic heterotrophic, nitrate reducing and methylotrophic, beta- and gamma-Proteobacteria that were more closely related to service water microorganisms than to air microbes. Rhodamine WT dye and fluorescent microspheres employed as contaminant tracers, however, indicated that service water contamination of most of the rock samples was < 0.01% during acquisition. The microbial contaminants most likely originated from the service water, infiltrated the low permeability rock through and accumulated within mining-induced fractures where they survived for several days before being mined. Combined PLFA and terminal restriction fragment length profile (T-RFLP) analyses suggest that the maximum concentration of indigenous microorganisms in the Carbon Leader was < 10(2) cells g(-1). PLFA, 35S autoradiography and enrichments suggest that the adjacent quartzite was less contaminated and contained approximately 10(3) cells gram(-1) of thermophilic, sulphate reducing bacteria, SRB, some of which are delta-Proteobacteria. Pore water and rock geochemical analyses suggest that these SRB's may have been sustained by sulphate diffusing from the adjacent U-rich, Carbon Leader where it was formed by radiolysis of sulphide.     

L-forms of aerobic spore-forming bacteria isolated from urologic patients

New data are presented on the ability of different aerobic spore-forming bacteria isolated from the organism of urological patients to produce L-forms of these microorganisms in the presence of penicillin and ampicillin. Bacillus cereus is shown to be the most resistant to these antibiotics.     

Soil and plant effects on microbial community structure

We investigated the effects of two different plant species (corn and soybean) and three different soil types on microbial community structure in the rhizosphere. Our working hypothesis was that the rhizosphere effect would be strongest on fast-growing aerobic heterotrophs, while there would be little or no rhizosphere effect on oligotrophic and other slow-growing microorganisms. Culturable bacteria and fungi had larger population densities in the rhizosphere than in bulk soil. Communities were characterized by soil fatty acid analysis and by substrate utilization assays for bacteria and fungi. Fatty acid analysis revealed a very strong soil effect but little plant effect on the microbial community, indicating that the overall microbial community structure was not affected by the rhizosphere. There was a strong rhizosphere effect detected by the substrate utilization assay for fast-growing aerobic heterotrophic bacterial community structure, with soil controls and rhizosphere samples clearly distinguished from each other. There was a much weaker rhizosphere effect on fungal communities than on bacterial communities as measured by the substrate utilization assays. At this coarse level of community analysis, the rhizosphere microbial community was impacted most by soil effects, and the rhizosphere only affected a small portion of the total bacteria.     

Study of Microflora in Malaysian Dried Fishes and Their Decontamination by Gamma-irradiation

The distribution of microorganisms in 10 samples of salted dried fish and the effects of irradiation of them were studied. The total aerobic bacteria in commercial dried fish were determined to be from 2 × 10⁴ to 3 × 10⁶ per gram. Mold counts were 1 × 10² to 7 × 10³ per gram with a lower amount of yeasts. In spoiled dried fish, total aerobic bacteria were determined to be 4× 10⁶ or 1 × 10⁷ per gram with a few yeasts. Coliforms were not isolated on MacConkey agar plates from any of the samples. The predominant bacteria occurring in spoiled dried fish were Pediococcus halophilus, Vibrio costicola and Planococcus sp. More than 50% of the molds consisted of the Aspergillus niger group, whereas lower amounts of the A. flavus, A. fumigatus and A. ochraceus groups, Penicillium chrysogenum series, etc. were also isolated from many samples of dried fish. All kinds of putrefactive microorganisms were radiation sensitive, and a dose of ca. 500 krad appears to be sufficient for extension of the shelf-life of dried fish from 2 to 4 times.     

Biofilm formation in water cooling systems

Biofilm formation on stainless steel samples immersed in cooling water has been evaluated by exposing metal samples to cooling seawater for 30 days. Anaerobic bacteria were then at 1.6 × 10⁶/cm², with sulphate-reducing species predominating. Aerobic bacteria and fungi were 2600 and 140/cm², respectively. After 60 days, numbers of aerobic microorganisms remained constant whereas the count of anaerobic microorganisms had increased to 1.8×10⁹/cm². Scanning electron microscopy showed the presence of morphologically different microorganisms in deposits and as a mucilaginous net. No signs of corrosion were detected on the stainless steel surface.The authors are with the Departamento de Engenharia Bioquimica Centro de Tecnologia, Bloco E. Universidade Federal do Rio de Janeiro Ilha do Fundão, 21941-900 Rio de Janeiro, Brazil     

Microflora of the posterior pharyngeal wall, larynx and postoperative wounds in patients after laryngectomy]

The study group were persons with risk factors of colonization by pathogenic strains and included smokers, patients suffering from paradontosis, and patients with visibly neglected oral cavity and teeth. We isolated and classified to the species or genera 488 microorganisms. Of posterior pharyngeal wall flora, 61% of were Gram-negative bacteria, represented predominantly by Haemophilus and anaerobic rods and aerobic cocci belonging to the Neisseria and Moraxella (Branhamella) genera. In the group of Gram-positive cocci (34% of the total number of microorganisms), oral streptococci, Stomatococcus mucilaginosus and Streptococcus pneumoniae were isolated most frequently. The affected by neoplastic lesions larynx, was colonized by similar bacterial groups. However, the incidence of Gram-positive cocci was higher. The main etiologic factor of purulent post-operative wound inflammations were methicillin-resistant Staphylococcus aureus strains (MRSA), which had been absent among the bacteria isolated from patients on admission.     

The use of fatty acid methyl esters as biomarkers to determine aerobic, facultatively aerobic and anaerobic communities in wastewater treatment systems

The use of fatty acid methyl esters (FAME) as biomarkers to identify groups of microorganisms was studied. A database was constructed using previously published results that identify FAME biomarkers for aerobic, anaerobic and facultatively aerobic bacteria. FAME profiles obtained from pure cultures were utilized to confirm the predicted presence of biomarkers. Principal component analysis demonstrated that the FAME profiles can be used to determine the incidence of these bacterial groups. The presence of aerobic, anaerobic and facultatively aerobic bacteria in the communities, in four bioreactors being used to treat different wastewaters, was investigated by applying FAME biomarkers.     

Growth and Reproduction of Microorganisms Under Extremely Alkaline Conditions

An aerobic and an anaerobic strain of bacteria were isolated from two extremely alkaline springs. Growth and reproduction of both microorganisms were demonstrated above pH 11.0.