Injury and repair of Escherichia coli damaged by acid mine water

Pure culture suspensions of Escherichia coli B/5 were stressed by exposure to filter-sterilized acid mine water (AMW). Sublethally injured survivors were examined for their ability to repair in several resuscitation media under different conditions of pH, temperature and oxygen availability. The repair process was monitored as a function of time by periodically removing samples from the repair media and simultaneously plating on nonselective and selective media. E. coli was severely damaged by AMW; however, sublethally injured survivors repaired when placed under favorable conditions. Optimal repair occurred in trypticase soy broth supplemented with 0.3% yeast extract (TSYB) at pH 7.0 and 35°C. Resuscitation did not occur in TSYB at pH 9.0, at an incubation temperature of 20°C, or in the absence of oxygen. Lauryl tryptose broth (LTB), which is recommended for the presumptive isolation of fecal coliforms, was unable to facilitate repair of injury. The presence of the surfactant, sodium dodecyl sulfate, as well as the nutrient composition of LTB, appeared to be responsible for the inability of this medium to permit recovery of AMW-stressed E. coli.     

Comparative survival and injury of Candida albicans and bacterial indicator organisms in streams receiving acid mine drainage

Microbiological studies were conducted to assess the survival and injury characteristics of Candida albicans and indicator bacteria in streams impacted by acid mine water (AMW) and organic wastes. Persistence of pure cultures of C. albicans in three AMW-polluted streams was studied in situ using environmental membrane diffusion chambers. Survival of the fungus (at least 3 days in AMW) indicated prolonged tolerance to acid conditions. In comparison, Escherichia coli was killed within several hours of acid stress. Persistence studies also demonstrated that C. albicans was less sensitive to seasonal water temperature fluctuations than E. coli or Streptococcus faecium. In addition to its prolonged survival, C. albicans incurred minimal sublethal injury whereas identical conditions of exposure resulted in significant injury to traditional indicator bacteria. The failure of standard microbiological procedures to detect AMW-damaged bacteria compromises the accuracy of public health safety determinations in these waters. On the other hand, the ability of C. albicans to survive in AMW streams with marked resistance to injury suggests its potential as a favorable alternative sanitary indicator organism for such environments.     

Effect of cavitation on chemical disinfection efficiency

This study brings out the potential efficacy of hybrid techniques for water disinfection. The techniques studied include hydrodynamic cavitation, acoustic cavitation and treatment with chemicals like hydrogen peroxide and ozone. The hybrid techniques which combine hydrodynamic cavitation, acoustic cavitation and hydrogen peroxide appear to be an attractive alternative to any one technique on its own for the reduction in the heterotropic plate count bacteria as well as indicator microorganisms like the total coliforms, fecal coliforms and fecal streptococci.     

Bacterial quality of tile drainage water from manured and fertilized cropland

Bacterial contamination of tile drainage water in three manured and one non-manured cropped fields was studied over a 4-year period at a large, mixed farm near Ottawa, Ontario, Canada. Concentrations of total coliforms, fecal coliforms (FC), fecal streptococci (FS) and Standard Plate Counts at 20 and 35°C, in both the drainage water and the applied dairy cattle liquid manure varied over a wide range. Bacterial concentrations in long-term winter-stored manure were much lower than in relatively fresh manure. Concentrations of FC and FS in the drainage water from the manured fields were lower than concentrations in the applied manure by 3–5 orders of magnitude. Bacterial concentrations in drainage water from all fields had low geometric mean and median values for all parameters tested. Water quality was satisfactory most of the time for recreational use or for use as a raw water source for drinking water supplies. Factors such as precipitation appeared to have a greater influence on drainage water quality than manure application. Influence of soil type on bacterial concentrations in drainage water from the manured fields was not evident. However, a lower unit-area tile outflow in coarse-textured soil compared to fine-textured soil indicated a greater potential in the former for fecal bacteria reaching groundwater beneath the tile drains.     

Evaluation of microbiological accumulation capability of the commercial sponge Spongia officinalis var. adriatica (Schmidt) (Porifera, Demospongiae)

This study was carried out to evaluate the microbiological accumulation capability of the demosponge Spongia officinalis var. adriatica. Six microbiological parameters were researched in two sampling periods in the water and in reared sponge samples coming from sites with different degrees of microbial contamination: an off-shore fish farm displaced off the Apulian coast (Southern Adriatic Sea) and a no-impacted area displaced into the Marine Protected Area of Porto Cesareo (Apulian coast-Ionian Sea). We detected the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci concentrations were detected by the MPN method. Bacterial densities were always higher in the sponge homogenates compared with the corresponding seawater in the sampling points and in both sampling periods. As regard vibrios, total culturable bacteria at 37 degrees C and fecal streptococci concentrations, the highest values were observed in the sponge samples coming from the off-shore fish farm during the summer period. The ability of Spongia officinalis var. adriatica to accumulate the microbial pollution indicators suggests that this species can be employed as a bioindicator for monitoring water quality.     

Some effects of shoreline cottage development on lake bacteriological water quality

Eighteen cottaged lakes and one uncottaged lake in Southern Ontario, and their inflowing streams were surveyed for bacterial indicators of pollution by membrane filter techniques. Water samples were taken on 5 consecutive days in the spring, summer, and fall of the year. Inputs of fecal indicator bacteria were determined through an analysis of variance. Fecal coliform and fecal streptococcus levels in lakewater varied in a seemingly erratic manner. When the bacterial densities at different points on the lake were examined by an analysis of variance, the locations with significantly higher densities of fecal coliforms and fecal streptococci were most often found along the cottaged shoreline. Total coliform densities did not show this relationship with the cottaged shoreline. In addition, after rainfall, a large increase in numbers of fecal coliforms were found in the cottaged lakes but not in the uncottaged lake. These findings indicated that the cottaged shoreline was a greater source of fecal indicator bacteria than the uncottaged shoreline. However, the highest concentrations of fecal indicator bacteria in these lakes were found in the inflowing streams. The bacteria in these streams arose from stormwater from undeveloped forested watersheds and were probably, therefore, of soil or animal origin.     

Bacteriological and virological analysis of water from four fresh water beaches

Water samples from four beaches were analysed for the presence of total coliforms, fecal coliforms, fecal streptococci, salmonellae and enteric viruses. Analysis of the data did not reveal any correlation between the presence of viruses in 20 l. of water and the presence of the enteric bacteria. There was also no correlation between the presence of salmonellae and the presence of the other bacterial indicators. A positive correlation between virus isolation and water turbidity was demonstrated when turbidity was greater than 10 N.T.U.     

A simple mathematical formula describing the survival kinetics of E.coli in natural waters

The fecal indicator bacteria (Escherichia coli, fecal coliforms and fecal streptococci) are typically used to measure the sanitary quality of water for recreational, industrial, agricultural and water supply purposes. They are natural inhabitants of the gastrointestinal tracts of humans and other warm‐blooded animals. These bacteria in general cause no harm. They are released into the environment with feces, and are then exposed to a variety of environmental conditions that eventually cause their death. In general, it is believed that the fecal indicator cannot grow in natural environments, since they are adapted to live in the gastrointestinal tract. Studies have shown that fecal indicator bacteria survive from a few hours up to several days in surface water, but may survive for days or months in lake‐sediments, where they may be protected from sunlight and predators. In ground water, temperature, competition with bacteria found naturally in the water, predation by protozoa and other small organisms, and entrapment in pore spaces may all contribute to their demise. We assume that pathogens similar to the fecal indicator bacteria die at the same rate as fecal indicator bacteria. Therefore, if we find relatively high numbers of fecal indicator bacteria in an environment, we assume that there is an increased likelihood of pathogens being present as well. This is even true of water, which has undergone treatment for drinking water purposes. The knowledge of enteric bacteria survival kinetic is very important for environmental scientists. For this purpose there are in present use various empirical formulas but the drawback of these formulas is their limited validity. Experience has shown that the results of calculations of this type may lack accuracy. The purpose of this scientific work was to express the survival kinetic of E.coli with a simple formula, which should be applicable, both to the solution of engineering problems and to future research.     

Transferable drug resistance in bacteria of coastal canal water and sediment

This study was undertaken to determine the comparative incidence of drug-resistant coliforms and salmonellae in the water and bottom sediments of six coastal canal communities which are used heavily for recreational activities. Of a total of 423 coliforms, 300 fecal coliforms and 100 salmonella isolates examined, 74.9% coliforms, 61.3% fecal coliforms and 71.0% salmonellae were resistant to one or more of the 12 antibiotics tested. Multiple resistance occurred in 48.9% coliforms, 32.7% fecal coliforms and 68.0% salmonella strains. A total of 178 coliforms, 137 fecal coliforms and 51 salmonella isolates were tested for the presence of resistance transfer factors, and 53.9%, 53.3% and 56.9% isolates, respectively, were capable of transferring their resistance patterns to Escherichia coli and/or Salmonella choleraesuis recipient strains. A significantly higher number of drug-resistant bacteria carrying R-factors (R⁺) was found to occur in sediment than in surface water.     

Faecal coliforms and faecal streptococci in streams in the new guinea highlands

Procedures used to assess faecal water contamination were developed in temperate regions and their applicability to tropical waters has been questioned. This paper reports a detailed study of faecal coliform and faecal streptococci concentrations in the streams of the Saka Valley in the Highlands of New Guinea. The Saka Valley supports large populations of humans and domestic pigs, whose faeces are washed into the streams by surface runoff following rain. Faecal coliforms and faecal streptococci, enumerated by the membrane filtration technique, were found to be excellent indicators of faecal pollution in the New Guinea Highlands. A consideration of faecal coliform to faecal streptococci ratios and other factors, leads to the conclusion that most faecal contamination derives from pigs. All waters investigated, with the exception of spring waters, were grossly contaminated with faecal material and these polluted streams provide the total domestic water needs of the New Guineans. The fluctuations in pollution levels are described and their association with water temperature, rainfall and turbidity is analysed. The interpretation of the water contamination data is made speculative by the lack of information on the coliform and streptococcal flora of fresh pig and human faeces under New Guinea Highlands conditions.     

The limitation of the ratio of fecal coliforms to total coliphage as a water pollution index

The fecal coliform populations of raw sewage, sewage lagoon effluent, and river water were determined using the most probable number technique. The total coliphage populations of the three water sources were determined using Escherichia coli B (ATCC 11303-1) host cells. The ratios of fecal coliforms to coliphage in the three water samples were 87:1, 4.2:1, and 0.15:1, respectively. The ratio of fecal coliforms to coliphage in stored raw sewage decreased from 87:1 to about 1:1 within 7 days at 20°C and within 28 days at 4°C. These changing ratios resulted from the greater longevity of the coliphage compared with that of the coliform bacteria. The use of the ratio of fecal coliforms to coliphage is not considered reliable as an index of when a fecal pollution event occurred because the ratio is influenced by prior contamination, presence of sediment, chlorination, and temperature.     

Survival of bacterial indicator organisms and enteric viruses in the Mediterranean coastal waters off Tel-Aviv

Field and laboratory studies were initiated on the die-away kinetics of coliforms and enteric viruses in coastal waters off Tel-Aviv. Samples were taken from the sewage boil located approx. 880 m out to sea and from three main Tel-Aviv beaches designated as sampling stations, ranging 3 km to the north and 2 km to the south. Routine bacteriological tests were made from these stations; in addition, approx. 50% of the samples were also examined for enteroviral content and occasionally, samples were taken from most of the other Tel-Aviv beaches for comparison of bacterial and viral content.The concentrations of total coliforms, fecal coliforms and fecal streptococci were correlated with the concentrations of enteroviruses. In general, the data suggests that the number of enteric bacteria in the sea was reduced relatively more rapidly than that of the enteroviruses, while fecal streptococci displayed a die-away rate similar to that of enteroviruses. The percentage of samples positive for enteroviruses was found to be lower during the summer months of the year than in the remaining months. The concentration of coliforms was also significantly lower during the summer months. This suggests that the decreased microbial level is associated with increased summertime daylight and solar radiation which affect the micro-organisms' die-away rate. About 76% of the positive enteroviral samples were found at beaches with a fecal coliform bacterial level considered safe for bathing beaches.     

The ecology of "fecal indicator" bacteria commonly found in pulp and paper mill water systems

Coliform bacteria have long been used to indicate fecal contamination of water and thus a health hazard. In this study, the in-mill water and external effluent treatment systems of seven typical Canadian pulp and paper mills were all shown to support the growth of numerous coliforms, especially Klebsiella Spp., Escherichia coli. Enterobacter spp., and Citrobacter spp. In all mills and most sampled locations, klebsiellas were the predominant coliforms. Although all but one of the mills had no sewage input and most disinfected their feed (input) water, all contained the most typical fecal indicator bacterium, E. coli. Many of the mill coliforms were classified as fecal coliforms by standard "MPN" and metabolic tests, but this was shown to be due to their thermotolerance, not their origin. Mill coliforms were shown not to be just simple transients from feedwater or furnish (wood), but to be continuously growing, especially in some of the primary clarifiers. Isolated mill coliforms grew very well on a sterilized raw combined mill effluent. The fecal streptococci (enterococci), alternative indicators of fecal health hazards, were common in all mills in the absence of sewage. Ten strains of E. coli isolated from four mills were all shown to be non-toxigenic strains of harmless serotypes. No salmonellas were found. Therefore, the use of total coliform, fecal coliform, enterococci, or E. coli counts as indicators of fecal contamination, and thus of health hazard in pulp and paper mill effluents or biosolids (sludges) known to be free of fecal input is invalid.     

Compositions of first flush and composite storm water runoff in small urban and rural watersheds,north-central Texas

The objective of this study was to evaluate chemical compositions of first flush and composite storm water runoff in four small, mixed land use watersheds in north-central Texas. The watersheds range from urban to rural, all discharging to a local lake providing aquatic habitat, recreation, flood control and drinking water. Automated devices near watershed outlets collected samples from seven storm events, from April 2001 to September 2003. Samples were analyzed for suspended solids, pesticides (diazinon, triazine and chlorpyrifos), nutrients (nitrogen and phosphorus), fecal coliforms and metals. Observed concentrations of most parameters were low relative to drinking water maximum contaminant levels (MCLs) and aquatic life criteria. Fecal coliforms and lead were detected in most samples, with highest lead concentrations in the most developed watershed, likely influenced by building material and automobile traffic. Pesticide concentrations were higher in an initial spring storm event following applications to control weeds and insects. Typical of urban runoff, most ammonia and phosphorus observations exceeded freshwater criteria for streams draining to lakes. Treated wastewater effluent accounted for the highest nitrogen and phosphorus observations. For most constituents, composite concentrations exceeded first flush concentrations, though differences were significant only for fecal coliforms.     

Pilot-plant comparative study of peracetic acid and sodium hypochlorite wastewater disinfection

Peracetic acid (PAA) use in wastewater disinfection was assessed by examining its performances in a pilot plant fed by the effluent from a conventional activated-sludge treatment plant. The influence of PAA initial concentrations (0.5-4.0 mg/l) and contact times (8-38 min) on the presence of seven microorganisms (total coliforms, fecal coliforms, fecal streptococci, Escherichia coli, Pseudomonas sp., Salmonella sp., and bacteriophages anti-E. coli) and on residual biocide and halogenated organic compound (AOXs) concentrations were evaluated. The data so obtained were compared to the corresponding results acquired using sodium hypochlorite (HYP) in the same experimental conditions. The biocide effect of PAA against total and fecal coliforms, E. coli, Pseudomonas sp. and Salmonella sp. was similar to that shown by HYP. The former disinfectant was, however, less efficient than the latter in the reduction of fecal streptococci and bacteriophages anti-E. coli. In both cases the biocide quantities initially introduced in the sewage resulted in the presence of significant concentrations at the end of the contact time. No significant variation of AOX content was detected in the effluent treated with PAA, whereas a progressive increment of such compounds was found when increasing quantities of HYP were added to the sewage.     

Use of in-stream reservoirs to reduce bacterial contamination of rural watersheds

An investigation into bacterial water quality problems was conducted on an interconnected stream and irrigation system within the Oldman River Basin of southern Alberta, Canada. Levels of indicator bacteria, including fecal coliforms, generic Escherichia coli and fecal streptococci, were repeatedly measured in streams and irrigation return canals of this river basin during the summer of 2001. Bacterial-loading segments of the irrigation/stream system were identified through a comparison of indicator bacteria levels in pairs of upstream and downstream sites. Mann-Whitney U-tests indicated that reservoirs significantly reduced bacterial counts. A temporal comparison of E. coli counts and river discharges suggested that these indicator bacteria do not originate from within in-stream sediments. Site-specific as well as cumulative inputs from a variety of non-point sources are likely to be responsible for the high downstream levels of indicator bacteria in this water system. The use of management practices such as in-stream reservoirs may significantly reduce contamination, and increase the quality of limited rural water supplies to allow their reuse and safe discharge into downstream water sources. The identification of bacteria-loading river/canal segments could also be used to prioritize restoration projects.     

Intermittent filtration of wastewater--removal of fecal coliforms and fecal streptococci

Removal of fecal coliforms and fecal streptococci was monitored over a period of 13 months in 14 buried pilot scale filters, treating septic tank effluent. The effects of grain size, hydraulic dosing rate and distribution method were investigated. Two different natural sands (sorted sand and unsorted sand) and three different types of light weight aggregates (LWA 0-4 mm, LWA 2-4 mm and crushed LWA 0-3 mm) were used. Intermittent dosing rates from 20 to 80 mm/day in 12 doses per day were applied to the filters by uniform pressure distribution or point application by gravity dosing. Removal of fecal coliforms was more than three orders of magnitude higher in the media with the finest grain sizes (unsorted sand) as compared to the coarsest media (LWA 0-4 mm and LWA 2-4 mm) operated under same conditions. Fecal streptococci were determined only in effluent from filters with LWA 0-4 mm and LWA 2-4 mm. Higher removal of fecal coliforms was observed in pressure dosed filters compared to gravity dosed filters. A lower removal was observed by increasing the hydraulic dosing rate. Minimum retention time was found to be a key parameter for predicting removal of bacteria in unsaturated, aerobic filters. At minimum retention times lower than about 50 h, there was a correlation of 0.96 between retention time and removal of fecal coliforms. Retention times longer than 50 h gave almost complete removal of fecal coliforms.     

Microbial partitioning to settleable particles in stormwater

The degree to which microbes in the water column associate with settleable particles has important implications for microbial transport in receiving waters, as well as for microbial removal via sedimentation (i.e. detention basins). The partitioning behavior of several bacterial, protozoan and viral indicator organisms is explored in three urban streams under both storm and dry weather conditions. The fraction of organisms associated with settleable particles in stormwater is estimated through use of a centrifugation technique which is calibrated using suspensions of standard particles (e.g., glass, latex). The fraction of organisms associated with settleable particles varies by type of microbe, and the partitioning behavior of each organism generally changes between dry weather and storm conditions. Bacterial indicator organisms (fecal coliforms, Escherichia coli, enterococci) exhibited relatively consistent behavior, with an average of 20-35% of organisms associated with these particles in background samples and 30-55% in storm samples. Clostridium perfringens spores exhibited the highest average level of particle association, with storm values varying from 50% to 70%. Results related to total coliphage partitioning were more variable, with 20-60% associated with particles during storms. These estimates should be valuable in surface water quality modeling efforts, many of which currently assume that all microbes exist as free (unattached) organisms.     

Enriching effects of Urban runoff on the productivity of a mesotrophic lake

Sewage was diverted from Lake Sammamish in September, 1968, and since then there have been no significant responses by trophic indicators which indicate the lake is beginning to recover. To explain this delay in response, extensive urban development in the lake's watershed was considered as a factor which might be acting to inhibit the lake's recovery. In vitro uni-algal experiments with water from 13 streams which drain urban and undeveloped areas showed that about half of the streams stimulated algal growth significantly, but these streams constitute less than 14 per cent of the lake's total water income. Of these six streams only two drain urban areas and account for less than 2 per cent of the water income. In situ experiments showed that no streams were significantly stimulatory to natural populations of phytoplankton. Other in situ studies showed that one urban stream and two from undeveloped areas caused substantial increases in periphyton growth after a 12-day period, although these increases were not statistically significant. Additional in situ nutrient limitation experiments in August of 1970 and 1971 revealed that P and N were limiting only in combination. Results from these studies do not support the contention that urban runoff is seriously enriching the limnetic region of Lake Sammamish.     

Indicator bacteria for fecal pollution in the littoral zone of Lake Kinneret

The distribution of fecal indicator bacteria in the littoral zone of Lake Kinneret have been monitored over seasons, geographical zones, station type (bathing beaches and streams), distance from shore line and water depth. Statistical analysis was used to determine the impact of these factors. The dominant contamination source are water streams flowing during winter; bacterial numbers were higher in zones where the proportion of stream type stations is higher. Bacterial numbers in water and sediment were higher close to the shore line.