Tank Water Samples Research Articles

Incidence of Legionella and heterotrophic bacteria in household rainwater tanks in Azumino, Nagano prefecture, Japan

Many administrative agencies in Japan are encouraging installation of household rainwater-storage tanks for more effective use of natural rainwater. Water samples were collected periodically from 43 rainwater tanks from 40 households and tested for the presence of Legionella species and the extent of heterotrophic bacteria in Azumino city, Nagano prefecture, Japan. PCR assays indicated the presence of Legionella spp. in 12 (30%) of the 43 tank water samples. Attempts were made to identify correlations between PCR positive samples, topography, pH, chemical oxygen demand (COD), atmospheric temperature and the numbers of heterotrophic bacteria. Between June and October, 2012, the numbers of heterotrophic bacteria in rainwater tanks and the values of COD positively correlated with the presence of Legionella species. In most of the Legionella-positive cases, heterotrophic bacterial cell counts were >10(4) CFU/mL. Moreover, Legionella species were less frequently detected when the COD value was >5 mg KMnO(4)/L. Therefore, at least in Azumino, Japan between June and October 2012, both heterotrophic bacterial counts and COD values may be considered index parameters for the presence of Legionella cells in rainwater tanks. Much more accumulation of such data is needed to verify the accuracy of these findings.

English

The application of methodologies that can rapidly and precisely identify Salmonella in both foods and water samples is of great interest to public health. Salmonella sp. was isolated from chicken carcasses and water samples from aquaculture tanks using both traditional culture methods and bacteriological analyses. DNAs from these isolates were extracted and Multiplex Polymerase Chain Reactions (mPCR) were performed using primers forinvA, fliC and sefA genes to detect the genus Salmonella and to differentiate the serovars Typhimurium and Enteritidis respectively. The results of these bacteriological analyses indicated that 94% of the chicken carcass samples were contaminated by 46 Salmonellasp. strains. mPCR analyses indicated that 43 of these strains belonged to the genusSalmonella. Among these isolates, 32% were genotyped as Salmonella enteritidis while none were identified as Salmonella typhimurium. Bacteriological analyses of the aquaculture tank water samples indicated that 73% were contaminated, and 11Salmonella sp. strains were isolated; mPCR analyses indicated that all of them belonged to the genus Salmonella, but no S. enteritidis and S. typhimurium serovars were identified. Multiplex PCR was found to be a very sensitive test that allowed rapid and reliable identification of these bacteria.   Key words: Salmonella enteritidis, Salmonella typhimurium, bacteriological analyses, multiplex polymerase chain reactions, aquaculture.

Gut bacteria associated with different diets in reared Nephrops norvegicus

The impact of different diets on the gut microbiota of reared Nephrops norvegicus was investigated based on bacterial 16S rRNA gene diversity. Specimens were collected from Pagasitikos Gulf (Greece) and kept in experimental rearing tanks, under in situ conditions, for 6months. Treatments included three diets: frozen natural (mussel) food (M), dry formulated pellet (P) and starvation (S). Gut samples were collected at the initiation of the experiment, and after 3 and 6months. Tank water and diet samples were also analyzed for bacterial 16S rRNA gene diversity. Statistical analysis separated the two groups fed or starved (M and P vs. S samples). Most gut bacteria were not related to the water or diet bacteria, while bacterial diversity was higher in the starvation samples. M and P samples were dominated by Gammaproteobacteria, Epsilonproteobacteria and Tenericutes. Phylotypes clustering in Photobacterium leiognathi, Shewanella sp. and Entomoplasmatales had high frequencies in the M and P samples but low sequence frequencies in S samples. The study showed that feeding resulted in the selection of specific species, which also occurs in the natural population, and might be associated with the animal's nutrition.

Quality of irrigation and drinking water in Nangarparkar Region of Thar Desert of Pakistan

The pioneer study evaluates water quality status in Nangarparkar area of Thar Desert of Pakistan. Water samples obtained from wells, ponds and storage tanks greatly varied in their chemical composition and nutrient contents. Percentage of hazardous well water samples for irrigation purpose were: pH: 30%; electrical conductivity (EC): 27%; total soluble salts (TSS): 100%; CO3–: 70%; HCO3–: 27%; Cl–: 53%; Na+: 23%; K+: 40%; Ca+2: 13%; Mg+2: 17%; PO4–: 7%; NO3–: 100% and for drinking: pH: 30%; EC: 50%; TSS: 100%; CO3–: 67%; HCO3–: 97%; Cl–: 100%; Na+: 100%; K+: 83%; Ca+2: 100%; Mg+2: 83%; NO3–: 0%. Percentages of hazardous pond water samples for drinking purpose are as follows: pH: 20%; EC: 0%; TSS: 100%; CO3–: 73%; HCO3–: 93%; Cl–: 100%; Na+: 100%; K+: 0%; Ca+2: 60%; Mg+2: 67%; NO3–: 40%. Percentages of hazardous storage tank water samples for drinking are expressed as follows: pH: 0%; EC: 0%; TSS: 100%; CO3–: 100%;HCO3–: 80%; Cl–: 100%; Na+: 100%; K+: 0%; Ca+2: 100%; Mg+2: 80% and NO3–: 60%. Storage tanks were more benign than wells and ponds. Nitrates were the dominant contaminant in irrigation water. Key words: Water quality, irrigation, drinking, Thar Desert, Nangarparkar, Pakistan.

Speciation and Frequency of Virulence Genes of Enterococcus spp. Isolated from Rainwater Tank Samples in Southeast Queensland, Australia

In this study, 212 Enterococcus isolates from 23 rainwater tank samples in Southeast Queensland (SEQ), Australia were identified to the species level. The isolates were also tested for the presence of 6 virulence genes associated with Enterococcus related infections. Among the 23 rainwater tank samples, 20 (90%), 10 (44%), 7 (30%), 5 (22%), 4 (17%), 2 (9%), and 1 (4%) samples yielded E. faecalis, E. mundtii, E. casseliflavus, E. faecium, E. hirae, E. avium, and E. durans, respectively. Among the 6 virulence genes tested, gelE and efaA were most prevalent, detected in 19 (83%) and 18 (78%) of 23 rainwater tank samples, respectively. Virulence gene ace was also detected in 14 (61%) rainwater tank samples followed by AS, esp (E. faecalis variant), and cylA genes which were detected in 3 (13%), 2 (9%), and 1 (4%) samples, respectively. In all, 120 (57%) Enterococcus isolates from 20 rainwater tank samples harbored virulence genes. Among these tank water samples, Enterococcus spp. from 5 (25%) samples harbored a single virulence gene and 15 (75%) samples were harboring two or more virulence genes. The significance of these strains in terms of health implications remains to be assessed. The potential sources of these strains need to be identified for the improved management of captured rainwater quality. Finally, it is recommended that Enterococcus spp. should be used as an additional fecal indicator bacterium in conjunction with E. coli for the microbiological assessment of rainwater tanks.

Source apportionment of heavy metals and ionic contaminants in rainwater tanks in a subtropical urban area in Australia

Due to prolonged droughts in recent years, the use of rainwater tanks in urban areas has increased in Australia. In order to apportion sources of contribution to heavy metal and ionic contaminants in rainwater tanks in Brisbane, a subtropical urban area in Australia, monthly tank water samples (24 sites, 31 tanks) and concurrent bulk deposition samples (18 sites) were collected during mainly April 2007–March 2008. The samples were analysed for acid-soluble metals, soluble anions, total inorganic carbon and total organic carbon, and characteristics such as total solid and pH. The Positive Matrix Factorisation model, EPA PMF 3.0, was used to apportion sources of contribution to the contaminants. Four source factors were identified for the bulk deposition samples, including ‘crustal matter/sea salt’, ‘car exhausts/road side dust’, ‘industrial dust’ and ‘aged sea salt/secondary aerosols’. For the tank water samples, apart from these atmospheric deposition related factors which contributed in total to 65% of the total contaminant concentration on average, another six rainwater collection system related factors were identified, including ‘plumbing’, ‘building material’, ‘galvanizing’, ‘roofing’, ‘steel’ and ‘lead flashing/paint’ (contributing in total to 35% of the total concentration on average). The Australian Drinking Water Guideline for lead was exceeded in 15% of the tank water samples. The collection system related factors, in particular the ‘lead flashing/paint’ factor, contributed to 79% of the lead in the tank water samples on average. The concentration of lead in tank water was found to vary with various environmental and collection system factors, in particular the presence of lead flashing on the roof. The results also indicated the important role of sludge dynamics inside the tank on the quality of tank water.

Effect of Textile and Dye Industrial Pollution on Surface WaterQuality and Soil Properties in Noyyal River Basin, Tamil Nadu

Contamination of the water resources has increasingly become a serious problem in many of the States including Tamil Nadu due the domestic and industrial waste waters. Only limited studies are available to comprehend the water quality of Noyyal river basin. Hence, this study was undertaken to characterise the quality of surface waters in Noyyal river and its adjoining tanks. The Noyyal river is continuously polluted due to many industries situated on its banks of the river. Textile and dye industries are the major industries that pollute the river. Twenty water samples were collected from various points of rivers and tanks during pre and post monsoon seasons of 2006 to 2007 and analysed for chemical parameters. The E.C. and pH values varied from 0.17 to 8.70 dSm -1 and 5.39 to 8.63 in river water. Cations were in the order of Na>Mg>Ca>K. Around 61.5 per cent of samples found to show RSC values of >2.5 m.e L -1 . SAR/SCAR values indicates that most of the samples (46 %) come under medium sodium class (S 2 ). The EC and pH values of tank water samples varied from 0.41 to 3.13 dSm -1 and 8.0 to 8.5 respectively. Majority of the samples (57 per cent) found to show RSC values of <1.25 m.e L -1 .SAR values indicates that most of the tank water samples (71.4 %) come under Low Sodium Class (S 1 ). Seasonal variations in water quality parameters were also observed in river and tanks.

Near-infrared spectroscopic assessment of contamination level of sewage

We examined the use of near infrared (NIR) spectroscopy as a rapid technique for the evaluation of sewage quality. Influent water samples, primary sedimentation tank water samples, and final effluent water samples were collected from sewage treatment facilities in Nagoya, Japan and their NIR spectra obtained. Partial least squares (PLS) models for total phosphate (TP), total nitrogen (TN), biochemical oxygen demand (BOD), total organic carbon (TOC), and turbidity of sewage water were constructed from the NIR data. The models provided good correlation between measurements obtained conventionally and those predicted from spectroscopy. Spectral variation induced by background interference in samples affected accuracy. Loading plots and score plots derived from PLS regression analysis resolved the background interference and allowed highly accurate predictions. Spectral variation induced by contamination in the sewage was a main predictor of sewage quality. These results show that NIR spectroscopy shows potential for in-line, non-destructive measurement of sewage quality.

Detection of Salmonella spp. Isolates from Specimens due to Pork Production Chains in Hue City, Vietnam

From August 2007 until March 2008, we perfomed a detection and epidemiological analysis for Salmonella spp. in specimens collected from pork production chains to improve the quality of meat hygiene conditions in Hue, Vietnam. A total of 306 specimens were examined for Salmonella spp., aerobic bacterial counts and coliform. Seven serovars of Salmonella spp. were detected in retail pork, slaughterhouse carcasses and environmental specimens with the following detection rates: 32.8% of retail pork, 15.5% of slaughterhouse carcasses, 47.4% of floors, 38.1% of weighing bowls, 28.6% of cooking boards and 16.7% of tank water samples. Based on these results, we recommend that exhaustive sterilization, washing, routine bacteriological examinations and treatments at low temperature are performed in slaughterhouses, transportation facilities and retail stores.

165 EFFECTS OF AGE, HORMONES AND HIBERNATION ON BREEDING SUCCESS IN BOREAL TOADS (BUFO BOREALIS)

The global amphibian extinction crisis has stimulated interest in captive breeding programs for this diverse taxa. The goals of this study were to test the effects of exogenous hormone injections (LHRH and hCG) and hibernation on breeding behavior and gamete release by the boreal toad, a temperate species. The 5-year study was initiated with 77 toadlets. Each year, a subset of female and/or male toads was hibernated for 5 months at 4°C. The remaining toads were maintained in a lab receiving 12 h of light daily and ample food and water. Within 48 h of removal from hibernation, toads were paired with hibernated or non-hibernated mates. All toads were weighed and pairs were randomly assigned to treatments. Toads were injected IP with 6 μg LHRH, 250 IU hCG, or saline control and observed for amplexus and egg production. Some treatment groups received a second hormone injection if eggs were not produced within 48 h. Eggs were counted and transferred to aquariums for tadpole and toadlet development. During years 1 to 3, sperm production was assessed in male toads by sampling tank water or urine samples after injections. Data were analyzed using unpaired t-tests and chi-square analyses. In year 1, only 19% of pairs overall exhibited amplexus, none of the males produced sperm and none of the females produced eggs. In year 2, only male toads injected with LHRH exhibited amplexus, and it was more prevalent (P < 0.05) in those that were hibernated than non-hibernated (54.0% and 33.3%, respectively). Percentage of pairs in amplexus in years 2 and 3 (56.9% and 100%) was greater (P < 0.05) than in year 1. Only one and two females produced eggs in years 2 and 3, respectively. In contrast, most hibernated (87.5%) and non-hibernated (75%) males produced sperm. In year 4, eight females produced eggs, but two of these died egg-bound. Interestingly, more (P < 0.05) non-hibernated (7/10) than hibernated (1/10) females produced eggs despite no differences (P ≥ 0.05) in proportion of pairs amplexing or time spent in amplexus between groups. Mean (±SD) weight of female toads producing eggs (58.9 ± 11.9 g) was greater (P < 0.05) than that for non-producing females (43.6 ± 7.0 g). Similarly, 4/7 non-hibernated females produced eggs in year 5, and their weights averaged (58.8 ± 8.3 g). All eggs were produced by females injected a single time with LHRH. Number of eggs per female varied (141–3307), and percentage of eggs developing to tadpoles was low (0–36.5%), but tadpoles were capable of developing into adult toads. In conclusion, two-year-old male boreal toads are mature, exhibiting amplexus and releasing sperm in response to LHRH injections. Females appear to mature at four years of age, and eggs are more likely to be produced by heavier females. Therefore, to enhance breeding success, males should be hibernated and injected with LHRH. In contrast, better productivity in females may be achieved by improving their body condition instead of subjecting them to winter hibernation prior to LHRH injection. Supported by: AZA Conservation Endowment Fund and Colorado Division of Wildlife.

Distribution of luminescent Vibrio harveyi and their bacteriophages in a commercial shrimp hatchery in South India

Luminescent Vibrio harveyi is a natural microflora of marine and coastal water bodies and is associated with mortality of larval shrimp in penaeid shrimp hatcheries. It is also known that the bacteriophages occur virtually in all places where their hosts exist. In this study, distribution of luminescent V. harveyi and the bacteriophages affecting these hosts was examined in a commercial Penaeus monodon hatchery during three shrimp larval production cycles, including a cycle affected by luminescent bacterial (LB) disease outbreak.Out of a total of 1195 samples drawn from seawater source, sand-filtered water, nauplius, zoea, mysis and post larval rearing tanks, maturation and spawning tanks, Artemia hatching tank and algal culture tanks processed using conventional microbiological techniques, 21.4% of the samples harboured luminescent bacteria. During the larval production cycle affected by LB disease (LBD), luminescent V. harveyi could be recovered from 52% of the hatchery samples, whereas during luminescent bacterial disease-free larval production cycle (LBDF), these bacteria could be recovered from only about 9% of the samples. The predominant source of luminescent bacteria was the brood shrimp and their rearing tanks in maturation and spawning facilities. 73% of the maturation and 80% of the spawning tank water samples harbored LB during LBD, whereas, only 20% and 32% of the maturation and spawning tanks respectively harbored LB during LBDF. LB could be isolated from 17% of the water samples in tanks from nauplius stage onwards with increasing counts that subsequently lead to LB disease.Bacteriophages affecting the luminescent V. harveyi could be isolated from as many as 36% (21% and 43% of the samples analysed during LBDF and LBD respectively) of a total of 181 water samples drawn from various sources in the hatchery, using 27 luminescent V. harveyi hosts by agar overlay technique. The maturation tank water samples were found to be the predominant source of bacteriophages, followed by spawning tank water samples as observed with the LB. Sixty five bacteriophages, 13 during LBDF and 52 during LBD were isolated, which were grouped in to seven types based on their plaque morphology.The study has indicated that the brooders, maturation and spawning facilities in the shrimp hatchery are the main source of luminescent V. harveyi and their bacteriophages and that occurrence of LB even in low counts during early larval stages can possibly lead to development of LB disease despite presence of bacteriophages in the larval rearing tanks.

Prevalence and Epidemiology of Salmonella spp. in Small Pig Abattoirs of Hanoi, Vietnam

The prevalence of Salmonella spp. in pigs was evaluated in a survey of small abattoirs in Hanoi, Vietnam. Cecal contents, carcass swabs, and tank water samples were collected for bacterial isolation in various media. Prevalence rates exceeded 50% in pig samples and 62% in water samples. This increased prevalence indicates the need for risk assessment evaluations along the entire production chain.

Detection of V. harveyi in shrimp postlarvae and hatchery tank water by the Most Probable Number technique with PCR

V. harveyi is the cause of serious disease in the shrimp industry in Thailand during cultivation. In this study, the gyrB gene of V. harveyi NICA, isolated from shrimp in Thailand, was sequenced. A pair of specific primers (A2B3) was designed that allowed amplification of a 363 bp gene fragment of V. harveyi. No cross reaction was detected in 17 other Vibrio species tested except for V. carchariae which is a synonym for V. harveyi. The possibility of using A2B3 for confirmation and enumeration of V. harveyi by PCR was demonstrated. Of 40 possible V. harveyi strains isolated from seafood on the basis of their growth on TCBS plates and biochemical reactions, 36 gave a reaction with the specific primers. The primers could detect V. harveyi at a level of as few as 15 cells/ml. The Most Probable Number (MPN) technique was applied to enumerate V. harveyi. We have demonstrated that when PCR was applied directly to the enrichment broth of shrimp artificially inoculated with V. harveyi, the MPN value was no different from the MPN value obtained using the standard technique with selective agar. This technique was employed to enumerate V. harveyi in postlarvae and hatchery tank water. V. harveyi were detected in 18 out of 21 postlarval samples and in 14 out of 21 tank water samples. The numbers of V. harveyi detected in postlarvae and water were 150–1.1 × 10 8/g postlarvae and 7–4.6 × 10 4/ml of water samples, respectively. Screening of postlarvae to reduce the high risk of V. harveyi contamination in cultivation ponds is suggested as a measure to prevent the catastrophic losses caused by V. harveyi disease.

Transmission and detection of Flavobacterium columnare in channel catfish Ictalurus punctatus

A specific and rapid PCR detection method for Flavobacterium columnare based on the 16S-23S rDNA intergenic spacer region (ISR) of the ribosomal RNA operon has been developed. The ISR of 30 F. columnare strains and other Flavobacterium species was amplified using universal primers and sequenced. Once F. columnare specific sequences within the ISR were recognized, specific PCR primers were designed against them (FCISRFL and FCISRR1). The primers were sensitive and able to detect as low as 7 colony forming units from pure culture by PCR. The new PCR detection method was applied to experimentally infected channel catfish. Two different experiments in which channel catfish fingerlings were infected by intramuscular injection or by immersion bath showed the advantage of the PCR method over standard culture techniques. F. columnare was detected by PCR in both tank water and catfish tissue samples with a higher frequency and in less time than standard microbiological methods. Furthermore, PCR detection confirmed that F. columnare can be transmitted horizontally indirectly through the water column without fish-to-fish contact. The newly developed PCR detection method for F. columnare was more sensitive and rapid than standard culture on bacteriological media for detection of F. columnare in channel catfish tissues and in tank water.

Use of MIDI–Fatty Acid Methyl Ester Analysis To Monitor the Transmission of Campylobacter during Commercial Poultry Processing

The presence of Campylobacter spp. on broiler carcasses and in scald water taken from a commercial poultry processing facility was monitored on a monthly basis from January through June. Campylobacter agar, Blaser, was used to enumerate Campylobacter in water samples from a multiple-tank scalder; on prescalded, picked, eviscerated, and chilled carcasses; and on processed carcasses stored at 4°C for 7 or 14 days. The MIDI Sherlock microbial identification system was used to identify Campylobacter-like isolates based on the fatty acid methyl ester profile of the bacteria. The dendrogram program of the Sherlock microbial identification system was used to compare the fatty acid methyl ester profiles of the bacteria and determine the degree of relatedness between the isolates. Findings indicated that no Campylobacter were recovered from carcasses or scald tank water samples collected in January or February, but the pathogen was recovered from samples collected in March, April, May, and June. Processing generally produced a significant (P < 0.05) decrease in the number of Campylobacter recovered from broiler carcasses, and the number of Campylobacter recovered from refrigerated carcasses generally decreased during storage. Significantly (P < 0.05) fewer Campylobacter were recovered from the final tank of the multiple-tank scald system than from the first tank. MIDI similarity index values ranged from 0.104 to 0.928 based on MIDI–fatty acid methyl ester analysis of Campylobacter jejuni and Campylobacter coli isolates. Dendrograms of the fatty acid methyl ester profile of the isolates indicated that poultry flocks may introduce several strains of C. jejuni and C. coli into processing plants. Different populations of the pathogen may be carried into the processing plant by successive broiler flocks, and the same Campylobacter strain may be recovered from different poultry processing operations. However, Campylobacter apparently is unable to colonize equipment in the processing facility and contaminate broilers from flocks processed at later dates in the facility.

Spread of Campylobacter spp. During Poultry Processing in Different Seasons

The presence of Campylobacter spp. on broiler carcasses and in scald tank water in a commercial poultry processing facility was monitored at monthly intervals from July through December. The spread of the pathogen had previously been monitored in the same facility from January through June of the same year. Campylobacter were enumerated on prescalded, picked, eviscerated, and chilled broiler carcasses; on processed carcasses stored at 4 C for 7 or 14 days, and in scald tank water samples. The fatty acid methyl o ester (FAME) profile of the Campylobacter isolates and the degree of relatedness between the Campylobacter isolates was determined using the MIDI Sherlock Microbial Identification System (MIS). Findings indicated that Campylobacter jejuni was present on carcasses and in scald tank water samples collected from July through December. Processing significantly (P < 0.05) decreased the number of Campylobacter recovered from broiler carcasses, however. Furthermore, significantly (P < 0.05) fewer C. jejuni were consistently recovered from the third tank of the multiple tank scald system than from the first tank. Findings indicated that poultry flocks may introduce several strains of C. jejuni into processing facilities. Additionally, different populations of the pathogen may be carried into the processing plant by successive broiler flocks, and some strains of C. jejuni may reappear in the same processing facility during different times of the year.

The effect of sampling time on the levels of micro-organisms recovered from broiler carcasses in a commercial slaughter plant

Changes in the levels of indicator micro-organisms and Listeria on broiler carcasses were determined at various stages of commercial broiler slaughter and processing. In addition, the effect of time of day that sampling was carried out within the plant on the microbial profile of samples was evaluated. Counts of total aerobic organisms (37°C and 22°C), Enterobacteriaceae, E. coli and Staphylococcus aureus on broiler skin samples were consistently lower on samples obtained during evening visits to the co-operating broiler slaughter plant when compared with corresponding morning samples. Counts of S. aureus were significantly lower for both morning and evening samples taken following final carcass rinsing when compared to pre-evisceration equivalents ( P<0.05). The number of total viable aerobic bacteria, Enterobacteriaceae and E. coli in scald tank water samples taken early each morning prior to processing start-up were significantly lower than corresponding samples obtained after flocks had been processed where an average of 3912 and 42 475 birds had been processed on morning and evening visits, respectively ( P<0.05). The prevalence of Listeria on broiler skin samples consistently increased for both morning and evening samples through the various stages of processing. For example, the prevalence on samples taken in the morning following defeathering, final carcass rinsing, in-line chilling and final carcass chilling was 10%, 40%, 56% and 72%, respectively. The most frequently recovered species of Listeria from these samples were L. innocua (86%), L. monocytogenes (6%), L. grayi (6%) and L. seeligeri (2%).

Isolation of Free Living Amoebas as a Highly Sensitive Index of Water Contamination

Safe drinking water is a rare commodity in India. Several water borne diseases are commonly reported from metropolitan cities of India, most likely due to unsatisfactory disinfection of municipal water. The analysis of the microbiological flora of the water supplied for drinking purposes shows that New Delhi water is biologically contaminated. Six hundred water samples obtained from New Delhi residential complexes included 96 from direct taps, 310 from overhead tanks used for storing the same water for urgent needs, and 194 were from water filter residues. The samples were repeatedly collected in every season for two consecutive years. Ninety percent of the water samples were found to be biologically contaminated. Most contaminated samples were from overhead water tanks (97.4 percent) and from filter residues (94.5 percent). Even direct tap water was found to be contaminated in more than 50 percent of the samples. The most common isolates were from the protozoan category, the free living amoeba (90.1 percent) and by aerobic bacteria (73.0 percent). Overhead tank water samples were co-contaminated with as many as 15 microorganisms. Isolation of free living amoebae was found to be the most sensitive tool of analyzing the water safety. It is proposed that after determining the microbiological contamination, the public health laboratories should modify the existing technique and must perform the cultures for free living amoebae on non-nutrient agar in addition to the standard coliform test.

Bacterial Populations Associated with the Dirty Area of a South African Poultry Abattoir

Bacterial populations associated with three sample types from the neck region of poultry carcasses in the dirty area of an abattoir were characterized. Sample types before and after scalding were skin only, feathers only, and a skin and feather combination. The neck skin of carcasses after the defeathering processing stage was also sampled. Bacterial populations associated with water from the scald tank, rubber fingers at the exit of the defeathering machine, and air in the dirty area were also characterized. Bacterial colonies (751) were randomly isolated from yeast extract-supplemented tryptone soya agar plates exhibiting 30 to 300 colonies. Micrococcus spp. were isolated in the highest proportion from pre- and postscalded carcass samples (63.5 to 86.1% of isolates), regardless of the sample type. Conversely, Enterobacteriaceae (40.3%), Acinetobacter (19.4%), and Aeromonas/Vibrio (12.5%) species predominated on neck skin samples taken from mechanically defeathered carcasses. Isolates from the rubber fingere were, however, predominantly Micrococcus spp. (94.4%). Bacterial groups isolated in the highest proportion from scald tank water samples were Micrococcus spp. (38.3%), species of Enterobacteriaceae (29.1%), and lactic acid bacteria (17.0%). Corynebacterium spp., species of Enterobacteriaceae, and Micrococcus spp. were dominant on air settle plates.

Trends in water quality of some wells in Saudi Arabia, 1984–1989

A survey of the quality of 4255 well samples collected from 1062 wells in the period 1984 through 1988, 388 samples collected in 1989, and 319 tank water samples distributed to houses, has been conducted throughout the Kingdom of Saudi Arabia. Sampling included seven regions in Saudi Arabia and analyzed for total dissolved salts, nitrate, nitrite, ammonium and faecal coliforms. The data generally showed a progressive improvement in the quality of well samples during the period under investigation. However, there are still a significant number of water samples showing high levels of pollutants. Nitrate levels of >45 mg l −1 were observed in 8% of the well samples in 1989 and 5% of them showed the presence of both elevated levels of nitrate and faecal coliforms. Five percent of the well samples in 1989 contained high levels of nitrate, ammonium and faecal coliform. It is concluded that human and animal wastes are the primary continuous source of pollution in the well water samples tested.