Viable Plate Counts Research Articles

Biotreatment of gas-phase VOC mixtures from fibreglass and composite manufacturing industry

The evolution of microbial community were monitored using culture-dependent and independent methods such as viable plate count and Denaturing Gradient Gel Electrophoresis (DGGE) to describe the influence of fungicides on microbial diversity. Relation between microorganisms variation and fungicide degradation was investigated to improve the system efficiency. Results showed a good capability of biomix to degrade pesticides. At the end of the experimentation time the concentration of most of pesticides was nearly to the complete degradation. No significant differences were observed in culture-dependent heterotrophic bacterial and fungal evolution during the treatment. DGGE analysis of bacterial community after two consecutive treatments with PC+DF and after the treatment with AZ+CY+FL showed the highest differences between treated samples and their controls. DGGE analysis showed a strong reduction of fungal community after PC+DF addition (10 th and 23 th day). At 64 th day fungicides were almost degraded and an evident enhancement of fungal biodiversity with the appearance of new species was shown. Interestingly, at the end of the experiment the microbial community exhibited a strong similarity between treated and untreated sample indicating that the variations of microbial community was only temporally.

The bactericidal efficacy of cold atmospheric plasma technology on some bacterial strains

Plasma, a mix of ionized gas molecules and free electrons, is often referred to as the fourth state of matter. There are different applications of plasma in our life starts from easy lighting to disease fighting and it’s nothing new. Fluorescent lights, air conditions and plasma televisions use it. One of its different types is atmospheric cold plasma, the possible applications for sterilization using cold plasmas range from the food industry to planetary space missions. The same technique could also be used on space craft leaving Earth to avoid transporting micro-organisms from Earth to other planets or moons. The use of toxic chemicals to sterilize medical instruments may soon be a thing of the past because the use of cold plasma to sterilize heat-sensitive reusable medical tools in a rapid, safe, and effective way is bound to replace the present method which uses a toxic gas as ethylene oxide, in addition to its use for air purification. Lately it is tested to prepare surfaces for bonding and kill bacteria on delicate living tissues. We report the results of an interdisciplinary collaboration formed to assess the sterilizing capabilities of the cold atmospheric plasma. This newly-invented source of plasma is capable of operating at atmospheric pressure in air and other gases, and of providing antimicrobial activity at room temperature as judged by viable plate counts. Plasma exposures have reduced log numbers of three tested bacterial strains namely, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa seeded on solid surfaces of Muller-Hinton agar at room temperature. Initial experimental data showed ≥5 log10 CFU reduction of bacteria when 5×106 cfu.ml-1 of samples seeded on MHA plates. Results showed >5 log10 CFU reduction with E. coli when exposed for up to 360 sec to plasma while the same exposure time was required for 5 log10 CFU reduction killing with S. aureus samples, the least affected by this treatment was Pseudomonas aeruginosa cell suspensions where there was a very few reduction in number of survivals (≤ 10% of the whole population) after the same exposure time application. For all microorganisms tested, a biphasic curve was generated when the number of survivors versus time was plotted in dose-response curves. In conclusion we can report that the atmospheric cold plasma generated by this method has proven sterilization (kill) capability against both gram-positive and gram-negative bacteria in different extents depending on special strain characteristics.

Comparison of PCR-DGGE and PCR-SSCP analysis for bacterial flora of Japanese traditional fermented fish products, aji-narezushi and iwashi-nukazuke

The bacterial flora of two Japanese traditional fermented fish products, aji-narezushi (salted and long-fermented horse mackerel (Trachurus japonicas) with rice) and iwashi-nukazuke (salted and long-fermented sardine (Sardinops melanostica) with rice bran), was analysed using non-culture-based polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) and culture-based PCR single-strand conformation polymorphism (SSCP) methods. Viable plate counts in aji-narezushi and iwashi-nukazuke were about 6.3-6.6 and 5.7-6.9 log colony-forming units g(-1) respectively. In the PCR-DGGE analysis, Lactobacillus acidipiscis was detected as the predominant bacterium in two of three aji-narezushi samples, while Lactobacillus versmoldensis was predominant in the third sample. By the PCR-SSCP method, Lb. acidipiscis and Lactobacillus plantarum were isolated as the predominant bacteria, while Lb. versmoldensis was not detected. The predominant bacterium in two of three iwashi-nukazuke samples was Tetragenococcus muriaticus, while Tetragenococcus halophilus was predominant in the third sample. The results suggest that the detection of some predominant lactic acid bacteria species in fermented fish by cultivation methods is difficult.

Inactivation of Escherichia coli, Listeria innocua and Saccharomyces cerevisiae by UV-C light: Study of cell injury by flow cytometry

Flow cytometry (FCM) is a powerful tool for analyzing physiological characteristics of microorganisms on a single-cell basis and identifying heterogeneities within population. This work analyzed the UV-C induced damage on Escherichia coli ATCC 11229; Listeria innocua ATCC 33090 and Saccharomyces cerevisiae KE162 cells by applying flow cytometry technique. The UV-C doses, obtained by altering the exposure time and measured by the iodide-iodate chemical actinometer, ranged between 0 and 5 kJ/m 2. E. coli; L. innocua and S. cerevisiae populations were quantified by plate count technique. For flow cytometry studies, cells were labeled with fluorescein diacetate (FDA) for detecting membrane integrity and esterase activity, and with propidium iodide (PI) for monitoring membrane integrity. The results showed that mechanisms of cellular damage differed according to time of exposure to ultraviolet radiation and the organism tested. E. coli and S. cerevisiae sub-populations with PI increased within the first minutes of UV-C treatment, without much change afterwards. On the contrary, FCM was used to detect the inactivation of those L. innocua sub-populations of viable microorganisms (maintaining metabolic activity) which were non-culturable due to membrane rupture and thus not detectable by viable plate count technique.

Pyrrolomycins as potential anti-staphylococcal biofilms agents

With the goal of discovering new anti-infective agents active against microbial biofilms, this investigation focused on some natural pyrrolomycins, a family of halogenated pyrrole antibiotics. In this study the anti-staphylococcal biofilm activity of pyrrolomycins C, D, F1, F2a, F2b, F3 and of the synthesized related compounds I, II, III were investigated. The susceptibility of six staphylococcal biofilms was determined by methyltiazotetrazolium staining. Most of the compounds were active at concentrations of 1.5 μg ml−1 with significant inhibition percentages. A few of the compounds were active at the lowest screening concentration of 0.045 μg ml−1. The population log reduction of activity against the two best biofilm forming Staphylococcus aureus strains as determined by viable plate counts is also reported. In order to adequately assess the utility of these compounds, their toxicity against human cells was evaluated. It is concluded that pyrrolomycins and synthetic derivatives are promising compounds for developing novel effective chemical countermeasures against staphylococcal biofilms.

Estimation of bacteriological levels in surface water samples to evaluate their contamination profile

The present work deals with the assessment of bacteriological contamination along with some physico-chemical parameters of water samples from Lahore canal. ANOVA showed that the observed p values of log-transformed viable plate counts, total suspended solids, turbidity, and biological oxygen demand are 0.000, 0.000, 0.000, and 0.000, respectively, which are < 0.05, while the p value of total coliforms, total fecal coliforms, and Escherichia coli are 0.728, 0.827, and 0.081, respectively which are > 0.05. Significant correlation was observed between log-transformed viable plate counts (CFU), biological oxygen demand, total suspended solids, and turbidity. Further regression analysis revealed that simple line regression model is fit for log-transformed viable plate counts and total suspended solids, log-transformed viable plate counts and turbidity, turbidity and total suspended solids, biological oxygen demand and total suspended solids, biological oxygen demand and log-transformed viable plate counts, and biological oxygen demand and turbidity.

Development and Performance Evaluation of a Low Cost Waste-Water Treatment Plant

The design, development and performance evaluation of a low cost waste-water treatment plant had been carried out. The aim was to harness the usefulness of waste-waters from residential, institutional and commercial sources. The facultative lagoon method of waste-water treatment was adopted. Biological analysis of treated effluents showed a decrease in coliform count from 18 x 10 2 to 16 x 10 2 per 100 ml after the first 28 days of treatment. There was a drastic reduction in viable plate count from 6.4 x 104 to 2.1 x 103 cfu ml -1 after filtration through activated carbon, fine sand and coarse sand medium. A decrease in chemical constituents (Zinc, Manganese and Copper) of treated waste-water was observed. However, no significant reduction in Iron and Nickel concentration was observed during the treatment period. Also, the pH of collected effluent samples which were found to be in the range of alkalinity before treatment become acidic to neutral after the 49 days of treatment in the development treatment plant. This research is useful in the management of scarce water resource especially in areas where water poverty is significantly felt during dry seasons. Keywords: Waste-water; Toxicity; Micro-organisms; Filtration tank; Low-cost; Colony forming Unit (CFU)

Biodegradation of International Jet A-1 Aviation Fuel by Microorganisms Isolated from Aircraft Tank and Joint Hydrant Storage Systems

Microorganisms contaminating international Jet A-1 aircraft fuel and fuel preserved in Joint Hydrant Storage Tank (JHST) were isolated, characterized and identified. The isolates were Bacillus subtillis, Bacillus megaterium, Flavobacterium oderatum, Sarcina flava, Micrococcus varians, Pseudomonas aeruginosa, Bacillus licheniformis, Bacillus cereus and Bacillus brevis. Others included Candida tropicalis, Candida albicans, Saccharomyces estuari, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Cladosporium resinae, Penicillium citrinum and Penicillium frequentans. The viable plate count of microorganisms in the Aircraft Tank ranged from 1.3 (+/-0.01) x 104 cfu/mL to 2.2 (+/-1.6) x 104 cfu/mL for bacteria and 102 cfu/mL to 1.68 (+/-0.32) x 103 cfu/mL for fungi. Total bacterial counts of 1.79 (+/-0.2) x 104 cfu/mL to 2.58 (+/-0.04) x 104 cfu/mL and total fungal count of 2.1 (+/-0.1) x 103 cfu/mL to 2.28 (+/-0.5) x 103 cfu/mL were obtained for JHST. Selected isolates were re-inoculated into filter sterilized aircraft fuels and biodegradation studies carried out. After 14 days incubation, Cladosporium resinae exhibited the highest degradation rate with a percentage weight loss of 66 followed by Candida albicans (60.6) while Penicillium citrinum was the least degrader with a weight loss of 41.6%. The ability of the isolates to utilize the fuel as their sole source of carbon and energy was examined and found to vary in growth profile between the isolates. The results imply that aviation fuel could be biodegraded by hydrocarbonoclastic microorganisms. To avert a possible deterioration of fuel quality during storage, fuel pipe clogging and failure, engine component damage, wing tank corrosion and aircraft disaster, efficient routine monitoring of aircraft fuel systems is advocated.

Bioindicators forRalstonia solanacearumrace 4: plants in the Zingiberaceae and Costaceae families

Ralstonia solanacearum (Rs) race 4 causes bacterial wilt of edible ginger (Zingiber officinale) and limits crop production in the tropics. The use of bioindicator plants was investigated as a method for determining whether or not a field is contaminated with Rs race 4 before replanting with a susceptible crop. Tissue-cultured edible ginger (TCG), micro-sized red ginger (Alpinia purpurata; RG) and micro-sized spiral ginger (Costus barbatus; SG) were evaluated for suitability for detection of Rs race 4. Candidate hosts were planted into the infested medium, and Rs populations in plant tissues, potting medium and drainage water were evaluated by viable plate counts and Immunostrips using a species-specific monoclonal antibody. TCG wilted completely within an average of 9 days at the highest (log 8 cfu/mL) level of inoculum, and within 19 days at the lowest (log 4 cfu/mL) inoculum level. RG wilted in 17–26 and SG in 29–39 days. The final populations of Rs race 4 in wilted TCG tissues, potting medium and drainage water were between log 8.8–9.3 cfu/g, log 7.0–7.4 cfu/g and log 4.8–5.0 cfu/mL, respectively, regardless of the initial population levels. RGand SG did not enhance Rs population levels as well as TCG. On average, the bioindicator hosts increased the Rs populations by 100 to 1000-fold, thereby enabling detection with a simple immunodiagnostic test.

Long-term tracking of microbial survivability and growth in a controlled environment

The ecological and histological study of a microbial population in a given environment provides important information leading to its survivability and growth. Current standard laboratory practices adopt culture on a medium housed in an incubated environment. However, large numbers of cultures are usually required to investigate the effects of variations in parametric conditions on the microbes. This can result in a high use of resources such as consumables and man-hours. Automated systems that are able to replenish fresh nutrients and extract metabolic waste for long-term monitoring are also limited. In this study, a system capable of real-time monitoring of microbe survival and providing a suitable environment for their growth is presented. Housed within its structure is a customized chamber with temperature control, pH regulation, nutrient providence and metabolic waste removal functions. To assess the reliability of the system, five sets of Staphylococcus aureus ATCC 29213 strains are cultured and monitored continuously for 96 consecutive hours. The survival and growth of the pathogens are verified by standard laboratory techniques such as viable plate count after each successive 24 h of monitoring. The findings herein suggest that the system is able to monitor the microbial population with minimal human intervention and can be a valuable long-term tracking tool.

Composition of the bacterial population of refrigerated beef, identified with direct 16S rRNA gene analysis and pure culture technique

The composition of the dominating population of freshly cut beef, and beef stored at 4 °C for 8 d, was studied by direct analysis of the 16S rRNA gene (PCR amplification, cloning and sequencing) and compared with pure culture technique where the isolates picked from the viable plate count were identified by sequencing of the 16S rRNA gene. The composition of the bacterial population was recorded at two different time points, at the start when the viable plate count of the meat was 4 × 10 2 colony forming unit (cfu) per cm 2 and when it was 5 × 10 7 cfu per cm 2. Direct gene analysis by PCR amplification generated 30 clones, and 79 isolates were picked from the plate count, and identified by 16S rRNA gene sequencing. At the low initial bacterial load of the beef, the two sampling strategies showed variations in the composition of species. Direct 16S rRNA gene analysis revealed a domination of Bacillus-like sequences while no such sequences were found in isolates from the viable plate count. Instead the population of the plate count was dominated by Chryseobacterium spp. In contrast, the two sampling strategies matched on the multiplying beef population, where both methods indicated Pseudomonas spp. as the dominating group (99% of the population-sequences), irrespectively of sampling strategy. Pseudomonas panacis/ Pseudomons brennerii was the dominating taxon (99% similarity to type strain), but sequences with highest similarity to Pseudomonas lundensis (99%), Pseudomonas beteli (99%) and Pseudomonas koreensis (100%) were also found.

Fluid Dynamics Impact on Bacterial Physiology: Biochemical Oxygen Demand

The interaction between fluid dynamics and microbiological organisms is an integral aspect of aquatic ecosystems that has received only sporadic attention over the years. The effects of fluid motion on bacterial growth kinetics and on the traditional biochemical oxygen demand (BOD) test were investigated. Laboratory experiments were performed to study the physiology of E. coli in a well-defined flow system with an emphasis on BOD measurements. Several methods were applied to quantify bacterial abundance and viability including viable plate counts; membrane integrity Live/Dead BacLight; respiratory 5-cyano-2,3-ditolyl tetrazolium chloride; and direct bacterial count 4′ 6 -diamidino-2-phenylindole staining methods. A turbulent fluid flow was generated using an oscillating grid reactor. Microscale fluid flow in the experimental setup was analyzed using a laser-Doppler velocimeter. Our results demonstrate that bacterial physiology and the corresponding BOD measurements depend on hydrodynamic mixing conditions...

Evaluation of antimicrobial activity of selected plant extracts by rapid XTT colorimetry and bacterial enumeration

The aim of this study was to screen and evaluate the antimicrobial activity of indigenous Jordanian plant extracts, dissolved in dimethylsulfoxide, using the rapid XTT assay and viable count methods. XTT rapid assay was used for the initial screening of antimicrobial activity for the plant extracts. Antimicrobial activity of potentially active plant extracts was further assessed using the “viable plate count” method. Four degrees of antimicrobial activity (high, moderate, weak and inactive) against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, respectively, were recorded. The plant extracts of Hypericum triquetrifolium, Ballota undulata, Ruta chalepensis, Ononis natrix, Paronychia argentea and Marrubium vulgare had shown promising antimicrobial activity. This study showed that while both XTT and viable count methods are comparable when estimating the overall antimicrobial activity of experimental substances, there is no strong linear correlation between the two methods.

Effect of a Metal Alloy Fuel Catalyst on Bacterial Growth

Many microorganisms have been demonstrated to utilize petroleum fuel products to fulfill their nutritional requirement for carbon. As a result, the ability of these microbes to degrade fuel has both a deleterious affect as well as beneficial applications. This study focused on the undesired ability of bacteria to grow on fuel and the potential for some metal alloys to inhibit this biodegradation. The objective of this study was to review the pattern of growth of two reference strains of petroleum-degrading bacteria, Pseudomonas oleovorans and Rhodococcus rhodocrous, in a specific hydrocarbon environment in the presence of a commercially available alloy. The alloy formulated and supplied by Advanced Power Systems International Inc. (APSI) is sold for fuel reformulation and other purposes. The components of the alloy used in the study were antimony, tin, lead, and mercury formulated as pellets. Surface characterization also showed the presence of tin oxide and lead amalgam phases. Hydrocarbon used for the study was primarily 87-octane gasoline. The growth of the bacteria in the water and mineral-supplemented gasoline mixture over 6-8 weeks was monitored by the viable plate count method. While an initial increase in bacteria occurred in the first week, overall bacterial growth was found to be suppressed in the presence of the alloy. Results also indicate that the alloy surface characteristics that convey the catalytic activity may also contribute to the observed antibacterial activity.

Discrepancy between viable counts and light output as viability measurements, following ciprofloxacin challenge of self-bioluminescent Pseudomonas aeruginosa biofilms

To utilize bioluminescence to follow the effect of ciprofloxacin challenge on Pseudomonas aeruginosa biofilms. The Sorbarod continuous perfusion culture system was used for the cultivation of biofilms of a self-bioluminescent strain of P. aeruginosa PAO1. Biofilms were challenged with ciprofloxacin (5 mg/L) in the perfusing medium for 3 h and allowed to recover to pre-challenge population levels before initiation of a second 3 h challenge. In addition to determining eluate and biofilm cell survival by conventional viable plate counts, light output was monitored via a luminometer and a low-light-level ICCD camera, to give an indication of metabolism. The effect of drug challenge on biofilm structure was investigated using an environmental scanning electron microscope, which allowed discernment of changes to the three-dimensional biofilm architecture. On challenge with ciprofloxacin, eluate light output measurements declined to a lesser extent than viable counts for the same samples and also indicated that post-challenge recovery of the biofilm metabolism did not occur as rapidly as suggested by viable count data. Photon detection by ICCD camera allowed real-time, non-invasive imaging of metabolic activity within intact biofilms. The application of a bioluminescent reporter strain to biofilm research provides valuable real-time positional data on the efficacy of anti-biofilm treatment strategies.

Enhanced Killing of Biliary Bacterial Biofilm Using Electroporation: An In Vitro Evaluation

Background: Bacterial biofilm is a known cause of chronic device related infections requiring removal of implanted device such as a biliary stent. Biofilm bacteria are resistant to antibiotic therapy requiring 100 to 1000 times minimum inhibitory concentration (MIC) for complete eradication. Electroporation (EP) - a pulsed electrical field induces cell membrane permeability and enhances penetration of drugs into bacterial cells. Aim: To determine effects of EP and antibiotics therapy in eradication of biofilm bacteria. Method: Mixed biofilm were formed on micro TFA filters (Applied Biosystems, CA) by incubation with E. coli (E) and Enterococcus (En) in ox bile for 72 hours. The established biofilm was tested against Ciprofloxacin at 100xMIC for E. coli (Cipro) or 4% tetra sodium EDTA (TE) with or without EP. The filters were inserted into cuvettes and electroporated (ECM 630, Harvard Apparatus, MA) with constant voltage, capacitance, pulse duration, frequency and number of pulses for 1 minute. The experiments were divided into 2 groups with 10 or 15 EP pulses and exposure to individual antimicrobials for 4 hours. Experiments included: 1. Control; 2. 10 pulses of EP at 1500 volts; 3. 4% TE; 4. Cipro at 100xMIC; 5. EP plus Cipro; 6. EP plus TE. Experiments were repeated using 15 EP pulses. The filters were rinsed and then sonicated in 5 ml sterile PBS to release the bacteria. Bacterial counts in colony forming units (CFU/cm2) were determined by serial dilution and viable plate count method. The experiments were repeated and the mean bacterial count (n = 2) was calculated and expressed as mean (log10 CFU/cm2) ± SD. Results: Mean control bacterial counts were (E 5.6-5.8, En 4.8-4.4). Compared with controls, EP at 10 pulses or Cipro alone produced a 100-fold (2 log) reduction in E. coli but no significant effects on Enterococcus; 2. EP plus Cipro produced a 100-fold decrease in E. coli and 10-fold decrease in Enterococcus. 3. TE alone killed all E. coli but not Enterococcus; 4. EP plus 4% TE produced a 100-fold decrease in Enterococcus. With 15 EP pulses, all E. coli were killed by Cipro. A combination of TE and 15 EP pulses killed ALL bacteria in the biofilm. The differences were statistically significant (Box plot, p < 0.001). Conclusion: Electroporation enhanced the killing effects of antibiotics/antimicrobials against established biofilm bacteria and may offer an alternative to prevent biliary biofilm and stent blockage. Background: Bacterial biofilm is a known cause of chronic device related infections requiring removal of implanted device such as a biliary stent. Biofilm bacteria are resistant to antibiotic therapy requiring 100 to 1000 times minimum inhibitory concentration (MIC) for complete eradication. Electroporation (EP) - a pulsed electrical field induces cell membrane permeability and enhances penetration of drugs into bacterial cells. Aim: To determine effects of EP and antibiotics therapy in eradication of biofilm bacteria. Method: Mixed biofilm were formed on micro TFA filters (Applied Biosystems, CA) by incubation with E. coli (E) and Enterococcus (En) in ox bile for 72 hours. The established biofilm was tested against Ciprofloxacin at 100xMIC for E. coli (Cipro) or 4% tetra sodium EDTA (TE) with or without EP. The filters were inserted into cuvettes and electroporated (ECM 630, Harvard Apparatus, MA) with constant voltage, capacitance, pulse duration, frequency and number of pulses for 1 minute. The experiments were divided into 2 groups with 10 or 15 EP pulses and exposure to individual antimicrobials for 4 hours. Experiments included: 1. Control; 2. 10 pulses of EP at 1500 volts; 3. 4% TE; 4. Cipro at 100xMIC; 5. EP plus Cipro; 6. EP plus TE. Experiments were repeated using 15 EP pulses. The filters were rinsed and then sonicated in 5 ml sterile PBS to release the bacteria. Bacterial counts in colony forming units (CFU/cm2) were determined by serial dilution and viable plate count method. The experiments were repeated and the mean bacterial count (n = 2) was calculated and expressed as mean (log10 CFU/cm2) ± SD. Results: Mean control bacterial counts were (E 5.6-5.8, En 4.8-4.4). Compared with controls, EP at 10 pulses or Cipro alone produced a 100-fold (2 log) reduction in E. coli but no significant effects on Enterococcus; 2. EP plus Cipro produced a 100-fold decrease in E. coli and 10-fold decrease in Enterococcus. 3. TE alone killed all E. coli but not Enterococcus; 4. EP plus 4% TE produced a 100-fold decrease in Enterococcus. With 15 EP pulses, all E. coli were killed by Cipro. A combination of TE and 15 EP pulses killed ALL bacteria in the biofilm. The differences were statistically significant (Box plot, p < 0.001). Conclusion: Electroporation enhanced the killing effects of antibiotics/antimicrobials against established biofilm bacteria and may offer an alternative to prevent biliary biofilm and stent blockage.

Prevalence Of Micro-Organisms In Flies And Meat Cuts In Uyo Abattoir, Akwa Ibom State

A total of 100 samples, 50 each of fresh meat cuts and flies were aseptically collected from Iba-Oku Abattoir in Uyo, Akwa Ibom State periodically and processed for quantitative and qualitative microbiological analysis using cultural procedures. Results of quantitative analysis revealed microbiological load of flies ranging from 1.8 (+ 0.02) X 10 6 to 1.83 ( + 0.33) X 10 6 cfu/g -1 while that of meat cuts ranged from 1.2 (+ 0.02) X10 5 to 1.25 (+ 0.33) X 10 6 cfu/g -1 . The viable plate count (VPC) of Micro-organisms on flies was significantly (P Staphylococus aureus as the most predominant organism, 48% and 50% respectively while Proteus was the least with 12% and 14% incidence in meat cuts and flies respectively. Apart from known mycotoxin producing Aspergillus and Penicillium species encountered in this work, the occurrence of Stapylococcus aureus, E. coli, Bacillus cereus, Staphylococcus epidermidis, Micrococcus roseus, Bacillus subtilis, Streptococcus, Klebsiella, Pseudomonas , and Salmonella species is indicative of gross contamination and constitute potential health hazard to consumers. Continuous microbiological surveillance of abattoirs is recommended to avert imminent danger of food borne intoxications. The public health significance of these findings are discussed in the paper. KEY WORDS: Microbial, Contamination, Meat cuts, Flies, Abattoir. Global Journal of Agricultural Sciences Vol.3(1&2) 2004:79-81

EFFECT OF TANK DESIGN AND TWO-PHASED FILTRATION ON CLEANLINESS LEVEL OF WATER HYDRAULIC SYSTEM

Filtration in water hydraulic system may be problematic, due to chemical, physical and biological contamination. This contamination may cause quick increase in the pressure difference over the filter element. The aim of this research was to test different kinds of tank sizes and filter combinations and to determine their effects on water quality in a water hydraulic system. In this paper the results of these experiments are presented. Experiments were made with pilot-scale water hydraulic systems. The systems induced no biological contamination and only a minimum amount of physical and chemical contamination. Filtered tap water was used as a pressure medium. The tested filter ratings (β>5000) were from 10 to 90 µm depth type elements and the three different tank sizes 62, 105 and 148 litres. Experiments were made with water without amendments, and water with nutrient and particle contamination. The test periods were up to four weeks. Pressure difference over the filter, fluid flow and temperature are monitored. Microbiological analyses consisted of total number of cells, heterotrophic viable plate counts and the determination of biofilm formation. In addition, dissolved organic carbon concentration and particle counts were determined. Solving the microbiological problems of water hydraulics requires new approach to tank design methods that support the long-term working of the water hydraulic system. It is possible to (1) reduce microbial growth in water and on surfaces with a proper tank design, (2) keep microbial growth under control and (3) considerably extend the filter lifetimes by using twophased filtration in water hydraulic systems.

A Short Communication: Prevalence of Microbial Contaminants on “Suya meat” sold in Awka Urban

“Suya” meat samples, collected from different “suya” spots in Awka Urban were examined for microbial contamination using standard methods. The results, indicated that the “suya meat” samples were contaminated with various species of bacteria and fungi. The bacterial isolates include Bacillus species, Staphylococcus aureus, staphylococcus epidermidis, Proteus spp, Micrococcus spp. and Serratia spp. Fungal isolates include Aspergillus flavus, Aspergillus niger, Fusarium spp and Aspergillus fumigatus . The sample collected from Tracas station gave higher total viable plate count, of 95.5 × 104 cfu/ml while a lower count of 37.5 × 10 cfu/ml was recorded for sample from beside Ubatel hotel. Key Words: “suya” meat, prevalence, microbial contaminants, hygiene. J. Trop. Microbiol Vol.1 2002: 89-91

Optimization of a rapid dot-blot immunoassay for detection of Salmonella enterica serovar Enteritidis in poultry products and environmental samples

An immunoassay was developed for the detection of Salmonella serovar Enteritidis in poultry and environmental samples. This assay consisted of a two-step procedure that involved an enrichment step using whole egg homogenate (EH) as the enrichment medium and detection by a monoclonal antibody (MAb)-based dot-blot assay. Egg homogenate enriched Salmonella Enteritidis was heated to 100°C for 10 min in the presence of cholic acid, a detergent, to liberate the lipopolysaccharide (LPS) antigen in gelled egg matrix. This was subsequently transferred onto a nitrocellulose membrane for detection with MAb 2F11. Several commercially available media were compared with egg homogenate for their relative ability to resuscitate and propagate Salmonella Enteritidis to detectable levels. Incubation in EH, trypticase soy broth (TSB), and lactose broth (LB) resulted in comparable levels of Salmonella Enteritidis as demonstrated by viable plate counts. Salmonella Enteritidis grown in TSB exhibited the greatest visual intensity showing a positive test when tested by the dot-blot assay. Incubation time necessary to detect one cfu of Salmonella Enteritidis was reduced from 20 to 10 h using TSB as the enrichment broth. Addition of ferrous sulphate or ferrioxamine E or cholic acid in the enrichment broth had negligible negative effects on the growth of Salmonella. Salmonella Enteritidis when incubated with a mixture of naturally contaminated or artificially inoculated competitive micro-organisms in environmental samples at a ratio of 1:10 2, was able to reproduce to detectable numbers for the immunoassay. This method was able to detect all phage types (PT 1, 6, 7, 8, 13, 13a, 14b, 21 and 28) with unique ribopatterns. The results demonstrated that Salmonella Enteritidis, when preenriched in a medium containing ferrous sulphate or cholic acid, could be readily detected in the presence of 100-fold higher competition of other micro-organisms.