scholarly journals Determination of cytotoxicity and invasiveness of heterotrophic plate count bacteria isolated from drinking water

2002 ◽  
Vol 2 (3) ◽  
pp. 115-122 ◽  
Author(s):  
D. Pavlov ◽  
C.M.E. de Wet ◽  
W.O.K. Grabow ◽  
M.M. Ehlers
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Heterotrophic Bacteria ◽  
Penicillin G ◽  
Plate Count ◽  
Heterotrophic Plate Count ◽  
Water Supplies ◽  
Plate Counts ◽  
Study Support ◽  
Heterotrophic Plate Counts

Evidence has been presented that some heterotrophic bacteria often detected in drinking water supplies possess features associated with pathogenicity. This suggests that even the low numbers of heterotrophic bacteria considered acceptable by drinking water specifications may constitute a health risk, particularly to immunocompromised consumers. In this study, 339 bacteria were isolated at random from routine heterotrophic plate count (HPC) tests on selected drinking water supplies in South Africa. In a first screen for potentially pathogenic properties, 188 of the isolates (55.5%) displayed a- or b-haemolysis on blood agar. Further analysis of the haemolytic isolates for enzymes associated with virulence revealed the presence of chondroitinase (5.3%), coagulase (16.0%), DNase (60.6%), elastase (33.0%), fibrinolysin (53.7%), gelatinase (62.2%), hyaluronidase (21.3%), lecithinase (47.9%), lipase (54.8%) and proteinase (64.4%) of the isolates. No fluorescein or pyocyanin was detected in any of the isolates. Among the haemolytic isolates 68.6% were resistant to oxacillin (1 μg), 59.6% to penicillin G (2 units), 47.3% to penicillin G (10 units), 53.7% to ampicillin (10 μg) and 42.6% to ampicillin (25 μg). Cytotoxicity, invasiveness and adherence properties of the haemolytic isolates was determined on HEp-2 and Caco2 cell lines. Among the haemolytic isolates 96% were cytolytic on the HEp-2 cell line. All the haemolytic isolates adhered to HEp-2 and Caco2 cells but gram-negative isolates tended to adhere in larger numbers than gram-positive isolates. HEp-2 cells were invaded by 42% of the haemolytic isolates. Heterotrophic bacteria, which most frequently revealed the above features associated with pathogenicity included species of the following genera: Aeromonas, Acinetobacter, Aureobacterium, Bacillus, Klebsiella, Moraxella, Pseudomonas, Staphylococcus, Tsukamurella and Vibrio. The results obtained in this study support earlier indications that bacteria detected by routine heterotrophic plate counts on drinking water supplies may include bacteria associated with potentially pathogenic properties. The extent to which these bacteria in drinking water supplies may constitute a health risk remains to be investigated.

Bacterial colonization of domestic reverse-osmosis water filtration units

1989 ◽  
Vol 35 (11) ◽  
pp. 1065-1067 ◽  
Author(s):  
Pierre Payment
Keyword(s):  
Drinking Water ◽  
Reverse Osmosis ◽  
Heterotrophic Bacteria ◽  
Bacterial Colonization ◽  
Water Filtration ◽  
Water Reservoirs ◽  
Colony Forming Units ◽  
Plate Counts ◽  
Bacterial Content ◽  
Heterotrophic Plate Counts

We have analyzed the bacterial content of water from the reservoirs of 300 reverse-osmosis units installed in households. The heterotrophic plate counts on R2A medium (20 and 35 °C) ranged from 0 to 107 colony forming units per millilitre (cfu/mL). Most reservoirs contained water with bacterial counts between 104 and 105 cfu/mL. The bacteria identified were Pseudomonas (not aeruginosa), Alcaligenes or Moraxella, Acinetobacter, Flavobacterium, and Chromobacterium. This report emphasizes the importance of bacterial colonization by heterotrophic bacteria in water reservoirs from domestic reverse-osmosis units.Key words: drinking water, bacteria, reverse-osmosis filter, regrowth.

Chlorine requirement for biologically stable drinking water after nanofiltration

2013 ◽  
Vol 14 (3) ◽  
pp. 405-413
Author(s):  
Y. Ohkouchi ◽  
Y. Yata ◽  
R. Bun ◽  
S. Itoh
Keyword(s):  
Drinking Water ◽  
Water Distribution ◽  
Flow Reactor ◽  
Heterotrophic Bacteria ◽  
Tap Water ◽  
Biological Stability ◽  
Bacterial Regrowth ◽  
Chlorine Residual ◽  
Plate Counts ◽  
Heterotrophic Plate Counts

There is considerable interest in minimizing the chlorine residual in Japan's tap water because of increasing consumer complaints about the chlorinous odor of drinking water. However, minimization of the chlorine residual requires stricter control of biodegradable organics in finished water to ensure biological stability during water distribution. In this context, we investigated the improvement of biological stability of drinking water by nanofiltration (NF). The removal of assimilable organic carbon (AOC) was 52% on average, but showed large seasonal variation. It was found to be difficult to maintain the acceptable AOC level for biologically stable water by NF. In addition, significant bacterial regrowth in NF permeates was still observed without chlorination, although 52% AOC was removed. Then, the chlorine concentration required to prevent bacterial regrowth during distribution of nanofiltrated water was determined using continuous-flow reactor systems. The heterotrophic plate counts (HPC) densities in biofilm were monitored at different chlorine conditions. The results indicated that the NF process could significantly reduce the chlorine requirement of the finished water. The relationship between free chlorine residual and HPC in biofilm formed from 1 μgC AOC showed that a trace level of chlorine residual, <0.1 mg/L, could inactivate heterotrophic bacteria and prevent biofilm formation.

scholarly journals Degradation of Bacterial Water Quality in Drinking Water after Bottling

2020 ◽  
Vol 14 (1) ◽  
pp. 78-83
Author(s):  
Ali Shahryari ◽  
Charlotte D. Smith ◽  
Abolfazl Amini
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Heterotrophic Bacteria ◽  
Positive Association ◽  
Ambient Air ◽  
Bottled Water ◽  
Plate Count ◽  
Biochemical Tests ◽  
Storage Duration

Background: The consumption of bottled water globally, including Iran, has increased tremendously in recent years. This study was designed to assess the bacteriological quality of bottled water and its compliance with the drinking water regulations. In addition, we evaluated bottled waters for the presence of a variety of genera of bacteria and the effect of storage duration on the extent of bacterial contamination. Methods: Four hundred samples of bottled water belonging to ten different Iranian brands with various production dates were purchased from supermarkets in Gorgan, Iran, from 2017 to 2018. Bacterial quality of bottled water was assessed using heterotrophic plate count (HPC) followed by usual biochemical tests for identification of bacterial genera, and by the API system. Results: The average HPC of bottled water was 9974 colony-forming units per milliliter (CFU/ml). Twelve genera were isolated, among which Bacillus spp. and Escherichia coli were the most and least abundant, respectively. Statistical analysis showed that there was a positive association between water quality and storage duration so that the highest microbial load occurred within the first to third months after bottling. Furthermore, the highest rate of contamination was observed in May when ambient air temperatures commonly reached 40 °C. Conclusion: The bacterial quality of bottled water was not according to the standard of drinking water quality. This study demonstrated the variation in bacterial levels after bottling, which indicates the presence of waterborne heterotrophic bacteria, some of which can pose severe health risks to consumers.

Sources of Uncertainty in Assessing the Health Risk of Cyanobacterial Blooms in Drinking Water Supplies

1994 ◽  
pp. 122-126 ◽  
Author(s):  
Steve E. Hrudey ◽  
Sandra L. Kenefick ◽  
Timothy W. Lambert ◽  
Brian G. Kotak ◽  
Ellie E. Prepas ◽  
...  
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Cyanobacterial Blooms ◽  
Water Supplies ◽  
Sources Of Uncertainty

Microcystin class of toxins: health effects and safety of drinking water supplies

1994 ◽  
Vol 2 (2) ◽  
pp. 167-186 ◽  
Author(s):  
T. W. Lambert ◽  
C. F. B. Holmes ◽  
S. E. Hrudey
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Health Risk ◽  
Health Effects ◽  
Tumor Promoter ◽  
Water Supplies ◽  
Blue Green Algae ◽  
Adverse Health Effects ◽  
Human Illness ◽  
Safety Of Drinking Water

The microcystins are produced by several species of common planktonic cyanobacteria found in surface waters, but their biological function remains unknown. The microcystins have been shown to be extremely potent hepatotoxins in a variety of experimental animals and they are lethal at low doses. Microcystin-LR, one of over 40 microcystin analogues, has also been shown to be a potent tumor promoter. The toxic effects of the microcystins have been attributed to the inhibition of protein phosphatases. This inhibition causes collapse of the cytoskeleton and interferes with a general signal transduction mechanism in cells. The presence of toxic cyanobacteria in surface water has been documented in all parts of the world. The microcystins have been related to a few incidents of human illness and several incidents of animal poisoning in Canada, United States, Australia, Europe, and Africa. Therefore, exposure to the microcystins is a potentially significant health risk and toxin removal from drinking water is becoming a concern worldwide. Conventional water treatment processes (coagulation/sedimentation, chlorination) have generally proven ineffective at removing microcystin toxins from drinking water. Activated carbon, ozone, and free chlorine have been effective in removing microcystins below detectable concentrations in laboratory experiments. Considering these factors, the occurrence of microcystins in drinking water supplies deserves serious attention to insure that adverse health effects are prevented.Key words: microcystins, hepatotoxins, cyanobacteria, blue-green algae, water treatment, health risk.

scholarly journals The Health Risk Associated with Chronic Diseases in Villages with High Arsenic Levels in Drinking Water Supplies

2016 ◽  
Vol 9 (4) ◽  
pp. 261-273 ◽  
Author(s):  
Orhan Gunduz ◽  
Coskun Bakar ◽  
Celalettin Simsek ◽  
Alper Baba ◽  
Alper Elci ◽  
...  
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Chronic Diseases ◽  
Water Supplies ◽  
High Arsenic

scholarly journals Quality assessment of roof-harvested rainwater in the West Bank, Palestinian Authority

2011 ◽  
Vol 9 (3) ◽  
pp. 525-533 ◽  
Author(s):  
A. K. Daoud ◽  
K. M. Swaileh ◽  
R. M. Hussein ◽  
M. Matani
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Human Health ◽  
Heterotrophic Bacteria ◽  
West Bank ◽  
Human Health Risk ◽  
Fecal Coliforms ◽  
The West ◽  
Guideline Values

Rain harvesting is becoming more common in the Palestinian Territories as a result of drinking water scarcity. Although it might pose serious human health risk, this water is being consumed without treatment in many areas of the West Bank. The present study evaluates the physicochemical and microbial quality of harvested rainwater that is used as potable water in the West Bank. Samples from roof-harvested rainwater storage tanks (n = 42) were collected in summer (SS) 2006/winter (WS) 2007. Physicochemical parameters measured were: temperature, pH, electrical conductivity, salinity, total dissolved solids, turbidity, nitrate, copper and lead. With few exceptions, all these parameters were within WHO guideline values. All samples (100%) were found to contain coliforms and to be heavily contaminated with heterotrophic bacteria. About 67% of all samples were contaminated with fecal coliforms. Specific PCR technique confirmed the presence of five pathogenic microorganisms that can be ordered according to their prevalence as: Citrobacter (83%) > Acinetobacter (78%) > Aeromonas (52%) > Pseudomonas and Campylobacter (7%). Prevalence of microorganisms in SS was higher than in WS. Although the physicochemical quality of most harvested rainwater samples was in accordance with WHO guidelines for drinking water, stored rainwater was significantly contaminated with bacteria resulting in significant human health risk from infectious diseases.

scholarly journals Pathogenic features of heterotrophic plate count bacteria from drinking-water boreholes

2016 ◽  
Vol 14 (6) ◽  
pp. 890-900 ◽  
Author(s):  
Suranie Horn ◽  
Rialet Pieters ◽  
Carlos Bezuidenhout
Keyword(s):  
Drinking Water ◽  
Extracellular Enzymes ◽  
Alcaligenes Faecalis ◽  
Gastric Fluid ◽  
Plate Count ◽  
Simulated Gastric Fluid ◽  
Heterotrophic Plate Count ◽  
Pathogenic Potential ◽  
Borehole Water ◽  
Human Intestinal Cells

Evidence suggests that heterotrophic plate count (HPC) bacteria may be hazardous to humans with weakened health. We investigated the pathogenic potential of HPC bacteria from untreated borehole water, consumed by humans, for: their haemolytic properties, the production of extracellular enzymes such as DNase, proteinase, lipase, lecithinase, hyaluronidase and chondroitinase, the effect simulated gastric fluid has on their survival, as well as the bacteria's antibiotic-susceptible profile. HuTu-80 cells acted as model for the human intestine and were exposed to the HPC isolates to determine their effects on the viability of the cells. Several HPC isolates were α- or β-haemolytic, produced two or more extracellular enzymes, survived the SGF treatment, and showed resistance against selected antibiotics. The isolates were also harmful to the human intestinal cells to varying degrees. A novel pathogen score was calculated for each isolate. Bacillus cereus had the highest pathogen index: the pathogenicity of the other bacteria declined as follows: Aeromonas taiwanensis>Aeromonas hydrophila>Bacillus thuringiensis>Alcaligenes faecalis > Pseudomonas sp. >Bacillus pumilus>Brevibacillus sp. >Bacillus subtilis>Bacillus sp. These results demonstrated that the prevailing standards for HPCs in drinking water may expose humans with compromised immune systems to undue risk.

Sign in / Sign up

Export Citation Format

Share Document