Total Heterotrophic Plate Count Research Articles

Physicochemical and bacteriological quality of swimming pools water in Kombolcha Town, Northeastern Ethiopia.

The use of swimming pool water for recreation, rehabilitation, and athletics is widespread around the world, especially in large Cities and Towns. However, poorly managed swimming pool water can facilitate the spread of illnesses connected to recreational water. Despite this, there is no evidence on quality of swimming pools water in Kombolcha Town. Therefore, this study was aimed to evaluate the physicochemical and bacteriological quality of swimming pools water in Kombolcha Town. A laboratory-based cross-sectional study was conducted from February to April, 2021 in Kombolcha Town. A total of 90 water samples were collected from the three outdoor swimming pools. The collected data of both physicochemical and bacteriological parameters were entered into Microsoft Excel 2010 and analyzed using SPSS version 25.0. One-way ANOVA was used to test whether there were statistically significant differences between different swimming pools. The level of significance was declared at a p-value of <0.05. In this study, out of all the pool water samples that were examined, 37.8% had pH values between 7.2 and 7.8, 36.7% had temperatures between 21°C and 32°C, and 26.7% had turbidity values that were within the WHO standard. Furthermore, only 16.7% of the pool water samples showed residual chlorine levels of 2-3 mg/L. In addition, only 27.8, 35.6, and 32.2% of the samples, respectively, met the WHO criterion for total coliform, fecal coliform, and heterotrophic plate count. The result indicates that most pool water samples did not fulfill both the physicochemical and bacteriological quality of the WHO standard limit for swimming pools. Thus, it is crucial to clean and regularly check the pool water, apply pool safety requirements, and raise pool user's awareness about the danger of pool water pollution through training.

Molecular Characterisation of Gut Bacteria in Wista Rat After Green Tea Consumption

Green tea can influence the gut bacteria by either stimulating or hindering the growth of specific species. This experimental study was carried out in Rivers State, Nigeria to molecularly characterize gut bacteria in Wista rats after green tea consumption. Twenty-five (25) rats divided into five groups were used; each group had five (5) rats having an average weight range of 70g – 130g. After acclimatization of 2 weeks, groups (2, 3, 4 &amp; 5) were feed with green tea extract based on standard method using oral gavage with rat feed pellet and water for seven (7) days and fourteen (14) days respectively based on their body weights and group 1 (control) was fed with rat feed pellet and water only for same duration and their weights recorded. Stool samples were collected aseptically by pulling from each group into sterile stool sample bottles and sent to the laboratory for immediate analysis. Conventional microbiological methods of culturing and molecular methods were utilized for identification of isolates, total heterotrophic plate count and antibiotic susceptibility were also done. The data from this study were analysed using SPSS version 23, to survey difference in gut bacterial count of wista rats after fed with green tea, rat weight across the study groups, and the values were expressed as mean ± SD at a 5% alpha level. The study reported a statistical difference in bacterial plate count at (P≤0.05) in Groups 2, 3, 4, and 5 after 14 Days of Acclimatization, after 7 days of Treatment and after further 14 Days of Treatment. Group 1 showed no statistical significance at P=0.212. Furthermore, there was significant difference in weight comparison at (P≤0.05) in rats contained in all groups after 7 days and after further 14 days of treatment, rats in group 1 showed weight gain. There was weight loss in all the treatment groups (2 ,3, 4, and 5). Antibiotic-resistant assay pattern of the isolates showed multiple drugs resistance to all the antibiotics used with Bacillus and Enterobacter being the most resistant isolates. The molecular characterization and identification of the isolates revealed close relatedness to Staphylococcus arlettae, Enterobacter cloacae, Enterobacter cancerogenus, Acinetobacter nosocomialis, Comamonas testosterone, Klebsiella veriicola, Bacillus thuringiensis, Bacillus pumilus and Bacillus cereus, it showed that the molecular technique proved to be more specific and accurate than the convectional technique in the identification and characterization of the isolates. Also, the gut bacterial count of the rats that were treated with the tea were significantly raised indicating that the tea has the potential to influence the abundance and diversity of gut bacteria. As seen in this study, molecular characterisation of gut bacteria identifies bacteria upto their specie level and they are influenced by diet.

Site specific bacterial load, enterobacterial occurrence and antibiotic susceptibility patterns in Nile Tilapia (Oreochromis niloticus), water and sediment from earthen aquaculture ponds

INTRODUCTION: Aquaculture is the most rapidly growing food production sector. The intensive nature of freshwater fish aquaculture is associated with practices which predispose aquaculture produce to bacterial contamination. To prevent losses due to bacterial diseases, there has been an increase in the uncontrolled use of antibiotics, a good prerequisite to the development of antibiotic resistance - a major global problem. Hence, we aimed at investigating the enterobacterial diversity and occurrence of antimicrobial resistance in Nile Tilapia and its earth pond environment. METHODS: fish samples, pond water and sediments were collected from four earthen ponds located at Yato, Cameroon, in three different collection trips for Total Heterotrophic Aerobic Plate Count (THAPC) and enterobacterial isolation. Bacterial characterisation and antibiotic sensitivity were assessed using the API 20E kit and the standard Kirby-Bauer disc diffusion method, respectively. RESULTS: THAPC ranged from 1.0 x 102 to 3.0x109 CFU/mL across samples and within each pond, bacterial loads were highest in fish parts and lowest in the surrounding environment. Sixteen enteric genera and 24 species were identified, with Escherichia coli (16.49 %) and Enterobacter cloacae (12.37 %) being most abundant, especially in the gills and intestines. The highest degree of resistance was observed with Amoxicillin and Ampicillin, with more than 60 % of tested isolates being resistant. Multiple drug resistance was also observed in all sample types, ponds and collection time points, and highest in fish parts. CONCLUSION: this study re-emphasizes the potential of freshwater fish aquaculture as carrier of human pathogenic and multiple drug resistant bacteria.

Effect of the Cleanliness of Spray Nozzle on the Concentration of Microorganisms in the Spray Water in Warm-Water Bidet Toilet Seats.

Bidet-toilets are widely used in households and public spaces in Japan. The effect of nozzle cleanliness on spray water quality of warm-water bidet toilet seats is unknown. We conducted a long-term experimental model-based study (2015-2016) and two survey-based studies (A: 2018-2019 and B: 2020-2021) at a university campus. Survey A measured the effect of nozzle cleansing on total viable count (TVC) and heterotrophic plate counts (HPCs) in spray water. Survey B measured the total organic carbon, residual chlorine concentration, TVC, and HPC of different fractions of sprayed water. We found no upstream migration of microbes from the nozzle to water tanks. While daily cleaning of the nozzle surface could reduce bacterial count in spray water, continuous discharge of water washed away bacterial contamination. Fecal indicator bacteria were in traces in spray water, indicating proper maintenance of these toilet seats.

Identification of surrogates for rapid monitoring of microbial inactivation by ozone for water reuse: A pilot-scale study

The complex contaminants in reclaimed water sources and delayed feedback of microbial detection have brought tremendous challenges to disinfection process control. The identification of sensitive and online surrogates for indicating microbial inactivation efficacy is vital to evaluate and optimize the disinfection technologies and processes. This study analyzes the inactivation of microbial indicators during ozone disinfection at a pilot-scale study over 5 months. It is identified that total fluorescence (TF) intensity, ultraviolet absorbance at 254 nm (UV254) and intracellular adenosine triphosphate (cATP) concentration can act as surrogates in predicting microbial inactivation by ozone. Particularly, the empirical linear correlations for log removal values (LRV) of TF, UV254 and cATP concentration are developed for the inactivation of four widely applied microbial indicators, namely the total coliforms, fecal coliforms, Escherichia coli (E. coli) and heterotrophic plate count (HPC) (R2 = 0.86–0.96). Validation analyses are further conducted to verify the robustness and effectiveness of empirical models. Notably, TF is considered as the most efficient surrogate due to its high sensitivity, accuracy and reliability, whereas cATP concentration is an efficient supplement to directly reflect total microbial counts. The study is important to provide a rapid and reliable approach for ozone disinfection efficiency evaluation and prediction.

Microbial implications of beef fat and pork fat in the environment

Developing countries are known to dispose of waste indiscriminately into their environment, off which fat is one of them. These fats release awful odor making passersby uncomfortable and also breeds microorganisms. Environmental factors such as rainfall, sunlight, and wind aid the migration of these fats to other sites, thereby leading to contamination. Total heterotrophic plate count of pork fat ranged from 4.0 x 105 cfu/g to 4.2 x 105 cfu/g and its total coliform plate count was from 3.8 x 105 cfu/g to 4.0 x105 cfu/g while the total heterotrophic plate count of beef fat ranged from 3.1 x 105 cfu/g to 3.5 x 105 cfu/g and its total coliform plate count was from 2.4 x 105 cfu/g to 2.8 x105 cfu/g. E.coli and Salmonella sp. were the highest occurring in both fats. Pork fat had more microbial count than beef fat. Fats can be converted to useful products, which will reduce waste in the environment. Statistical analysis showed a significant difference in mean counts of pork and beef fat samples at p≤0.05.

Characterization of Autochthonous Bacterial Isolates with The Potentiality to Degrade Spent Engine Oil from Contaminated Soil Area Enriched with Glycine max

This study was conducted to identify and characterize bacteria capable of degrading spent oil contaminated soil. The physicochemical parameters of used engine oil were analyzed according to existing standards, while the total heterotrophic plate counts (HBC) and hydrocarbon utilizing bacteria counts were ascertained with the pour plate methods using nutrient agar and minimal salt agar (MSA) media respectively. The results indicated a mean total HBC ranging from 2.86 ± 0.08 to 5.76 log10 CFU/g and mean hydrocarbon utilizing bacterial counts from 1.32 ± 0.09 to 3.82 ± 0.25 log10 CFU/g, with samples enriched with Glycine max (Soybean) recorded to have the highest bacterial counts. The phenotypic identification of the hydrocarbon utilizing bacteria as sources of carbon and energy showed the presence of two primary bacterial genera: Bacillus and Micrococcus.However, from the overall 50 counted colonies, the frequency of occurrence for Bacillus was 41 (82 %) whereas, the Micrococcus was (9) 18%. The obtained data, confirmed the breakdown capacity of autochthonous (indigenous) organisms notably; Bacillus in the reduction of pollutants linked with oil spillage. This provides for reliable and promising approach of ameliorating crude oil pollutants and its inherent threats. &#x0D; Keywords: Soil, spent oil, Glycine max, degrading bacteria, isolation and bioremediation

Effects of roofing materials on harvested rain water quality

The effects of roof materials (corrugated iron, aluminum and asbestos) on the quality of harvested rainwater were evaluated in this study. The physical, chemical and bacteriological characteristics of rainwater collected from the different roof materials were analyzed and the results compared with WHO standard for potable water. The results of the physical analysis revealed that the colour, turbidity, total solids and total dissolved solids fell within WHO acceptable standards for potable water. Also, the calcium and magnesium hardness as well as nitrate and sulphate content of the sampled water fell within WHO permissible limits. The results, however, showed that harvested rain water within the study area is slightly acidic with average pH values of 6.13, 6.25 and 6.15 respectively for the corrugated iron, aluminum and asbestos roof materials respectively. The water samples analyzed had traces of Lead and Iron with average values of 0.605mg/L and 0.715mg/L of Lead as well as 0.38mg/L and 0.52mg/L of Iron for the corrugated and asbestos roof materials respectively. These values exceeded the WHO permissible limits of 0.01mg/L and 0.3mg/L for Lead and Iron respectively. The microbiological indicators assessed showed no detection for E. coli , while the total heterotrophic plate and total coliform counts fell within permissible limits. However, the presence of heavy metals (iron and Lead) in the rainwater samples in concentrations that exceed WHO permissible limits is an indication of high contamination of the water samples, hence, it is recommended that the rainwater samples should be suitably treated before human consumption. Keywords: roof materials, harvested rainwater, permissible limits, human consumption

Examining the physicochemical and microbial qualities and mineral content of selected brands of bottled water marketed and consumed in Asaba, Delta State, Nigeria

The quality of bottled water sold in Asaba, Delta State, Nigeria, was investigated in this study. Six (6) brands of highly consumed bottled water were randomly selected for evaluation of physicochemical parameters, metallic and nonmetallic inorganic constituents, and microbial properties. The study revealed that physicochemical parameters such as pH, TDS and Chloride ranged between 6.63±0.03-7.54±0.02, 3.3±0.8-88.4±6.1 and 2.48±0.6-39.3±3.6 respectively, while the metal contents were highly variable amongst the bottled water examined. The study also showed from bacteriological analysis, that 5.2 % of tested samples had Klebsiella sp., Streptococcus faecalis and Pseudomonas aeruginosa . Values for the physicochemical and non-metal inorganic elements were below the prescribed maximum limits of the World Health Organization (WHO) and Standard Organization of Nigeria (SON). Generally, the bottled waters were found to be microbiologically safe, going by the results of total coliform and heterotrophic plate count and were also not contaminated by heavy metals. A direct comparison of the values obtained with the mineral water categorization system showed low mineral content and hence most suitable for low-sodium diets. The study recommends regular monitoring and analysis of bottled waters sold and consumed in Nigeria for quality assurance. Keywords: Bottled Water, Water Quality, Public Health, Regular Monitoring, Asaba

Effect of chloramine concentration on biofilm maintenance on pipe surfaces exposed to nutrient-limited drinking water

This study addresses the effect of specific monochloramine concentration on biofilm density and bacterial functional potential in nutrient-limited water. The efficacy of monochloramine residual maintenance on biofilm density was studied at a range of 0.5 to 2.0 mg/l, using a 3:1 (w/w) dosing ratio of chlorine to ammonia, with the provision of low-nutrient water (0.18 mg/l as total organic carbon, 0.055 mg/l as biodegradable dissolved organic carbon, and 10.5 μg/l as assimilable organic carbon) using a granular activated carbon (GAC) filter. Biofilm density was monitored using biofilm bacteria counts and analysis of the physiological substrate utilisation profiles in Biolog gram-negative (GN) micro-plates. The monochloramine residuals were maintained stable in the low-nutrient water pipes, which contributed to the inhibition of biofilm density. Increasing the monochloramine residual from 0.5 to 2.0 mg/l suppressed the total cells and heterotrophic plate count (HPC) bacteria in the biofilms by about 1 and 2 log units, respectively. The biofilm HPC densities were more sensitive to monochloramine residual, and the reduction in biofilm HPC densities expressed as log CFU/cm 2 showed an exponential relationship with the increase in monochloramine residual. The Biolog micro-plate-based community-level assay showed that the biofilm communities occurring at 3 levels of chloramination were distinguished by the differences in their substrate utilisation potentials. The functional/metabolic potential of the biofilm community’s ability to utilise specific substrates was much lower at higher monochloramine concentration. Results suggest that the maintenance of a consistently high-level monochloramine residual in the low-nutrient water system led not only to a reduction in biofilm density on pipe surfaces but also depressed potential functional/metabolic ability of the biofilm community. Keywords : biofilm, monochloramine residual, low-nutrient water, HPC, physiological substrate utilisation profile, GAC

Effect of post-harvest interventions on surficial carrot bacterial community dynamics, pathogen survival, and antibiotic resistance

Strategies to mitigate antibiotic-resistant bacteria (ARB), including human pathogens, on raw vegetables are needed to reduce incidence of resistant infections. The objective of this research was to determine the effectiveness of standard post-harvest interventions, sanitizer washing and cold storage, to reduce ARB, including antibiotic resistant strains of the human pathogen E. coli O15:H7 and a common spoilage bacterium Pseudomonas, on raw carrots. To provide a background inoculum representing potential pre-harvest carryover of ARB, carrots were dip-inoculated in dairy cow manure compost slurry and further inoculated with known ARB. Inoculated carrots were washed with one of three treatments: sodium hypochlorite (50 ppm free chlorine), peroxyacetic acid (40 ppm peroxyacetic acid; 11.2% hydrogen peroxide), tap water (no sanitizer), or no washing (control). Washed carrots were air dried, packaged and stored at 10 °C for 7d or 2 °C for up to 60 d. Enumeration was performed using total heterotrophic plate counts (HPC), HPCs on antibiotic-containing media (“ARBs”), E. coli O157:H7, and Pseudomonas sp. immediately after washing (0 d) and after 7 d of storage. In addition to the cultured bacteria, changes to the surficial carrot microbiota were profiled by sequencing bacterial 16S rRNA gene amplicons to determine the effect of sanitizer wash, storage temperature, and time of storage (0, 1, 7, 14 and 60 d). Storage temperature, addition of a sanitizer during wash, and duration of storage significantly affected the bacterial microbiota (Wilcoxon, p < 0.05). Inclusion of either sanitizer in the wash water significantly reduced the log CFU/g of E. coli O157:H7 and Pseudomonas sp., as well as HPCs enumerated on cefotaxime- (10 μg/ml), sulfamethoxazole- (100 μg/ml), or tetracycline (3 μg/ml) supplemented media compared to the unwashed control (ANOVA, p < 0.05). However, no significant reductions to bacteria resistant to vancomycin or clindamycin occurred after washing and storage. Members of the Proteobactetria, Firmicutes, Actinobacteria, Planctomycetes, and Acidobacteria comprised the bacterial carrot microbiota. The diversity of the carrot microbiota was significantly affected by the temperature of storage and by extended storage (60 d), when spoilage began to occur. There were no significant differences to the relative abundance of bacterial groups associated with the type of sanitizer used for washing. Results of this study indicate that inclusion of a sanitizer in wash water, followed by storage at 2 °C, might be an effective strategy to prevent re-growth of pathogenic E. coli O157:H7 and reduce levels of bacteria resistant to certain antibiotics on carrots.

English

The most common and wide spread health risk associated with drinking water is microbial contamination. The aim of this study is to assess microbial contamination of drinking water, starting from source to distribution systems. Water samples from the Arba Minch town of Southern Ethiopia were collected randomly from the main source before chlorination, reservoir after chlorination and from different points of distribution lines. Total coliforms, fecal coliforms and heterotrophic plate count (HPC) were determined from collected water samples. Coliforms were analyzed by using the most probable number (MPN) method. About 93.3% of collected water samples were contaminated with total coliforms and 16.7% of distributed tap water was contaminated with fecal coliforms. Most of the analyzed water samples had high number of viable bacteria or HPC (&gt;5 log), and total coliforms. The HPC ranged from 1.9 log of bacteria in the chlorinated water in reservoir tank to 8.44 log in the source water before chlorination. Overall, the quality of drinking water suggests that the distribution lines are the most likely point of microbial contamination. Therefore, regular bacteriological monitoring and maintaining residual chlorine in distribution system is mandatory. Key words: Coliforms, drinking water, heterotrophic plate count, microbiological point of contamination. &nbsp

Microbiological assessment of maize ogi cofermented with pigeon pea.

Maize was cofermented with pigeon pea for ogi production and evaluated for microbiological qualities. White maize and pigeon pea were mixed at ratios of 90:10, 80:20, 70:30, 60:40, and 50:50, respectively, with 100:0 serving as the control. Mixtures were cofermented for 96 h at 27 ± 2°C, and microbiological and sensory qualities analyzed were carried out using analysis of variance. Values were significant at p ≤ .05. Results showed that there was a gradual decrease in the pH and increase in total titratable acidity (TTA), respectively, during fermentation in all the samples. At the end of fermentation, pH ranged from 3.47 to 4.27 and TTA ranged from 0.47% to 0.54%, respectively. Total heterotrophic count (THPC) ranged from 5.76 to 5.90 log cfu/g; lactic acid bacteria (LAB) from 6.15 to 5.98 log cfu/g; and yeasts from 5.51 to 5.79 log cfu/g. Microorganisms isolated were lactic acid bacteria (Lactobacillus buchneri, L. casei, L. pentosus, Pediococcus pentosaceus), yeasts (Saccharomyces cerevisiae, Candida kefyr, C. krusei, C. tropicalis), molds (Aspergillus niger, A. flavus, Penicillium oxalicum, Mucor racemosus and Rhizopus stolonifer) and other aerobic bacteria (Klebsiella oxytoca, Enterobacter amnigenus, Staphylococcus xylosus, Bacillus subtilis, B. firmus, Corynebacterium kutscheri, C. striatum, and C. afermentans). In conclusion, the total heterotrophic plate count (THPC) in fortified maize: pigeon pea products was very high. This could constitute health hazards to infants as weaning foods. However, the microbial loads could be reduced through heat treatment as ogi is usually boiled or treated with boiled water before consumption and it can therefore be concluded that the fortified maize: pigeon pea products could be used as weaning foods.

Microorganism levels in spray from warm-water bidet toilet seats: factors affecting total viable and heterotrophic plate counts, and examination of the fluctuations and origins of Pseudomonas aeruginosa.

The objectives of this study were to conduct an appropriate microbial evaluation of warm-water bidet toilet seats. Health-related advantages and disadvantages have been associated with using warm-water bidet toilet seats, which are classified according to the tank type, including tanks equipped with reservoir water heaters and on-demand tankless systems equipped with an instantaneous water heater. However, related bacterial research is sparse. Here, we performed a long-term survey of the behavior of microorganisms (i.e., the total viable count (TVC), heterotrophic plate counts (HPCs), and Pseudomonas aeruginosa count) in a university campus. We also examined the differences between the tank and on-demand types, and the origins of P. aeruginosa. A low TVC (≤1/mL) in the spray waters from both on-demand and tank-type warm-water bidet toilet seats showed low bacterial contamination, although there was an increase in HPC, i.e., growth of biofilms, inside in the warm-water bidet toilet seats. When P. aeruginosa was detected in spray water over an extended duration, the P. aeruginosa origin was considered as either from feces or tap water. Collectively our findings demonstrate that hygienic safety of warm-water bidet toilet seats is being maintained overall.

Management of Risks From Water and Ice From Ice Machines for the Very Immunocompromised Host: A Process Improvement Project Prompted by an Outbreak of Rapidly Growing Mycobacteria on a Pediatric Hematopoietic Stem Cell Transplant (Hsct) Unit.

BACKGROUND In 2011, pediatric hematopoietic stem cell transplant (HSCT) patients were moved from an older hospital to a new children's hospital. To minimize bacterial growth in the new hospital's water during construction, the plumbing system was flushed and disinfected before occupancy. However, 6 months after occupancy, an increased incidence of rapidly growing mycobacteria (RGM) was detected in clinical cultures. Over 10 months, 15 pediatric HSCT patients were infected, while no pediatric HSCT patients had been infected in the preceding 12 months. OBJECTIVE To determine the cause of the outbreak and to interrupt patient acquisition of RGM. METHODS Water samples were collected from water entering the hospital and from drinking water and ice machines (DWIMs) from the old and new hospitals. Total heterotrophic plate counts (HPCs, CFU/mL) of water were undertaken, and select isolates were identified as RGM. RESULTS The cause of the outbreak was increased bacterial levels in the water (including RGM) in the DWIMs in the new (2011) hospital. Tests revealed higher HPCs in drinking water and ice from the DWIMs in the new hospital than in the DWIMs in the old hospital. Ultimately, HPCs were reduced by several different interventions. CONCLUSION In response to an RGM outbreak, HSCT patients were banned from ingesting DWIM ice and water and bottled water was provided. Since this interverntion 4 years ago, no additional RGM isolates have been identified in HSCT patient cultures. Our measures to reduce HPCs to goal levels in drinking water from DWIMs were successful, but the HPCs for ice have not consistently reached the goal of <500 CFU/mL. Infect Control Hosp Epidemiol 2017;38:792-800.

Indicator bacteria community in seawater and coastal sediment: the Persian Gulf as a case

BackgroundThe aim of present work was to assess the concentration levels as well as vertical distribution of indicator bacteria including total coliform, fecal coliform, Pseudomonas aeruginosa, and Heterotrophic Plate Count (HPC) in the marine environment (seawater and coastal sediments) and evaluate the correlation between indicator bacteria and some physicochemical parameters of surface sediments as well as seawaters.MethodsA total number of 48 seawater and sediment samples were taken from 8 stations (each site 6 times with an interval time of 2 weeks) between June and September 2014. Seawater and sediment samples were collected from 30 cm under the surface samples and different sediment depths (0, 4, 7, 10, 15, and 20 cm) respectively, along the Persian Gulf in Bushehr coastal areas.ResultsBased on the results, the average numbers of bacterial indicators including total coliform, fecal coliform, and Pseudomonas aeruginosa as well as HPC in seawater samples were 1238.13, 150.87, 8.22 MPN/100 ml and 1742.91 CFU/ml, respectively, and in sediment samples at different depths (from 0-20 cm) varied between 25 × 103 to 51.67 × 103, 5.63 × 103 to 12.46 × 103, 17.33 to 65 MPN/100 ml, 36 × 103 to 147.5 × 103 CFU/ml, respectively. There were no statistically significant relationships between the indicator organism concentration levels with temperature as well as pH value of seawater. A reverse correlation was found between the level of indicator bacteria and salinity of seawater samples. Also results revealed that the sediment texture influenced abundance of indicators bacteria in sediments. As the concentration levels of indicators bacteria were higher in muddy sediments compare with sandy ones.ConclusionResult conducted Bushehr coastal sediments constitute a reservoir of indicator bacteria, therefore, whole of the indicators determined were distinguished to be present in higher levels in sediments than in the overlying seawater. It was concluded that the concentration levels of microbial indicators decreased with depth in sediments. Except total coliform, the numbers of other bacteria including fecal coliform, Pseudomonas aeruginosa and HPC bacteria significantly declined in the depth between 10 and 15 cm.

Membrane Fouling and Chemical Cleaning in Three Full-Scale Reverse Osmosis Plants Producing Demineralized Water

Membrane fouling and cleaning were studied in three reverse osmosis (RO) plants. Feed water was secondary wastewater effluent, river water, and surface water. Membrane autopsies were used for fouling characterization. Fouling layer measurements included total organic carbon (TOC), adenosine triphosphate, polysaccharides, proteins, and heterotrophic plate counts. In all locations, membrane and spacer fouling was (bio)organic. Plant chemical cleaning efficiencies were evaluated from full-scale operational data and cleaning trials in a laboratory setup. Standard cleaning procedures were compared to two cleaning procedures specifically adapted to treat (bio)organic fouling using commercial blend cleaners (mixtures of active substances). The three RO plants were impacted by irreversible foulants causing permanently decreased performance in normalized pressure drop and water permeability even after thorough chemical cleaning. The standard plant and adapted cleaning procedures reduced the TOC by 45% on average, with a maximum of ~80%. In general, around 20% higher biomass removal could be achieved with adapted procedure I compared to adapted procedure II. TOC measurements and SEM showed that none of cleaning procedures applied could remove foulants completely from the membrane elements. This study underlines the need for novel cleaning approaches targeting resistant foulants, as none of the procedures applied resulted in highly effective membrane regeneration.

Prevalence of plasmid-mediated multidrug resistance determinants in fluoroquinolone-resistant bacteria isolated from sewage and surface water.

Fluoroquinolones (FQs) are fully synthetic broad-spectrum antibacterial agents that are becoming increasingly popular in the treatment of clinical and veterinary infections. Being excreted during treatment, mostly as active compounds, their biological action is not limited to the therapeutic site, but it is moved further as resistance selection pressure into the environment. Water environment is an ideal medium for the aggregation and dissemination of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs), which can pose a serious threat to human health. Because of this, the aim of this study was to determine the number of fluoroquinolone-resistant bacteria (FQRB) and their share in total heterotrophic plate counts (HPC) in treated wastewater (TWW), and upstream and downstream river water (URW, DRW) samples where TWW is discharged. The spread of plasmid-mediated quinolone resistance (PMQR) determinants and the presence/absence of resistance genes to other most popular antibiotic groups (against tetracyclines and beta-lactams) in selected 116 multiresistant isolates were investigated. The share of FQRB in total HPC in all samples was rather small and ranged from 0.7 % in URW samples to 7.5 % in TWW. Bacteria from Escherichia (25.0 %), Acinetobacter (25.0 %), and Aeromonas (6.9 %) genera were predominant in the FQRB group. Fluoroquinolone resistance was mostly caused by the presence of the gene aac(6′)-1b-cr (91.4 %). More rarely reported was the occurrence of qnrS, qnrD, as well as oqxA, but qnrA, qnrB, qepA, and oqxB were extremely rarely or never noted in FQRB. The most prevalent bacterial genes connected with beta-lactams’ resistance in FQRB were blaTEM, blaOXA, and blaCTX-M. The blaSHV was less common in the community of FQRB. The occurrence of bla genes was reported in almost 29.3 % of FQRB. The most abundant tet genes in FQRB were tet(A), tet(L), tet(K), and tet(S). The prevalence of tet genes was observed in 41.4 % of FQRB. The highest prevalence of multidrug-resistant (MDR) microorganisms was detected in TWW and DRW samples. It indicates that discharged TWW harbors multiresistant bacterial strains and that mobile PMQR and ARGs elements may have a selective pressure for species affiliated to bacteria in the river water.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-6221-4) contains supplementary material, which is available to authorized users.

분변오염 기저귀에서 분리한 플라스틱과 펄프의 미생물 저감화

Three different methods (simple washing of plastic and pulp sample, washing after direct heating of the diapers, and the heating after washing of plastic and pulp sample) were carried out to decrease total coliforms and heterotrophic plate count (HPC) in the diaper's plastic and pulp. Plastic and pulp samples were obtained from diaper by treatment with 10% CaCl2 and 4% sea salt water, dilution with 1,000 ml tap water, and draining by using sieves. Three times washing was the most appropriate for the reduction of microorganisms in plastic and pulp. By three times washing, the number of total coliforms in the plastic and pulp samples showed 92.8% and 99.8% of decrease, respectively, and the number of HPC showed 97.3% of decrease in the plastic and 98.5% of decrease in the pulp. The washing after direct heating of the fecal contaminated diapers was not effective because HPC in the plastic and pulp samples were still detected about 2-3 log CFU/g in the plastic and 1-2 log CFU/g in the pulp, respectively, even after heating at 60℃, 80℃, 100℃ for 12 h. Meanwhile, total coliforms and HPC were completely sterilized at 80℃ for 4 h by heating after washing of plastic and pulp samples, suggesting that this method was the most appropriate method for the reduction of microorganisms in plastic and pulp obtained from fecal contaminated diapers.

Comparison of chemical, biological and physical quality assessment of indoor swimming pools in Shahrekord City, Iran in 2013.

Previous studies have shown that mismanaged swimming pools could transmit water-borne diseases. The objective of the present study was the quality assessment of chemical, biological and physical characteristics of swimming pools in Shahrekord city, southwest of Iran.The two main indoor swimming pools of Shahrekord city were considered during the summer and winter of 2013. The number of 459 samples were analysed from swimming pools, showers and dressing rooms for chemical, biological and physical quality assessment. The most prevalent fungi were Aspergillus (48.91%), Penicillium (22.9%), Nocardia (11.31%), Cladosporium (8.41%). Rhizopus (6.18%), Scopulariopsis (6.21%), Fusarium (5.31%), and Mucor (1.38%). The most fungal contamination sites for both swimming pools were showers.Results showed that the values of total faecal coliform, Pseudomonas aeruginosa, Legionalla, Escherichia coli and Heterotrophic Plate Count (HPC) for both swimming pools exceeded the guidelines, except for Staphylococcus aureus. The correlation coefficient between bathers load and total faecal coliform, heterotrophic bacteria was 0.949. The turbidity, free residual chlorine, and hardness of both swimming pools were not compliance with standard guidelines. Therefore, the improvement of disinfection and cleaning procedures is necessary, due to the different users and daily bather loads of each pool, as well as monitoring the water quality and increasing of the knowledge of swimming pool users on the risks of these potential diseases.