Human health risk assessment of toxic elements in fish species collected from the river Buriganga,Bangladesh

Abstract

Multielement (48) analysis was carried out of various fish species collected from river Buriganga, the most polluted river in Bangladesh to assess human health risk by toxic elements. Sixteen elements that is, Be, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Hg, Pb, Bi, and U, were taken into account due to their toxicities on human health. Results show that concentrations of elements in various fish species were higher in winter than those in monsoon. Among 16 elements, Mn, Cu, Zn, Cd, Ba, Pb were above Food Safety Guideline in some fishes in winter. THQ and TTHQ/HI values were less than 1 for all fishes in monsoon while THQ and TTHW/HI values were more than 1 for most of fishes in winter. These results suggesting non-carcinogenic health hazard through consumption of contaminated fishes. Only As showed low cancer risk while no cancer risk was observed for other toxic elements in monsoon. In winter, Pb showed only moderate cancer risk for Mystus vittatus (site-7) while for other fishes low cancer risk was found by Pb. It can therefore be concluded that there is human health risk in consuming of fishes collected from river Buriganga especially in winter.     

Formed elements of the blood of the fresh water mussel,Lamellidens corrianus

The formed elements of the blood of L. corrianus are comprised exclusively of amoebocytes, whose total number is approximately 758 per cubic mm of blood. The blood cells are of three types, viz. acidophils, large basophils and small basophils, which are respectively 26.32%, 60.20% and 13.48% of the total blood cell population. The cytoplasm of the acidophils is filled with large acidophilic granules, while that of the basophils contains fine basophilic granules. Acidophils are the largest (7.6 μ × 6.7 μ), large basophils are smaller (6.5 μ × 4.9 μ), and small basophils are the smallest (4.1 μ × 3.8 μ). The nucleus occupies a very small volume of the cell (approx. 1/9th) in acidophils, a larger volume (approx. 1/4th) in large basophils, and a major volume (approx. 3/4th) in small basophils. The blood cells show amoeboid movement, which is brought about by means of broad lamellate pseudopodia. Large basophils move very slowly, acidophils move faster, and small basophils move quite fast. Fine bristle-like filipodia help the blood cells in getting entangled to form clumps. Filipodia are more abundant in large basophils and acidophils which pertake more actively in clumping than small basophils which rarely possess filipodia. Clumping is a reversible process which is promoted by mechanical agitation of blood.     

Antimicrobial resistant coliform bacteria in the Gomti river water and determination of their tolerance level

The distribution of resistance to ampicillin, chloramphenicol, sulfonamides, tetracycline, and streptomycin among coliform in the Gomti river water samples was investigated. The coliform populations were isolated on Mac Conky and eosin methylene blue (EMB) agar plates supplemented with antibiotics. The incidence of resistance among the coliform population varied considerably in different drug and water sampling sites. Coliform bacteria showed lower drug resistant viable count in sampling site-III (receiving treated wastewater) as compared to more polluted site-I and site-II. Viable count of coliform population obtained on both medium was recorded higher against erythromycin from sampling site-III. Lower viable count of coliforms was recorded against tetracycline in site-II and III. Similar resistance pattern was obtained in the frequency of E. coli and Enterobacter species from all the three sampling sites. Percentage of antibiotic resistant E. coli was observed higher than Enterobacter spp among the total coliforms against all antibiotics tested without Erythromycin and penicillin in site-I and II respectively. Isolates of E. coli and Enterobacter spp. showed their tolerance level (MIC) in the range of 2-100 against the antibiotics tested. Maximum number of isolates of both genus exhibited their MICs at lower concentration range 2-5µg/ml against ciprofloxacin, tetracyclin and amoxycillin.

Abbreviations

EMB - Eosin methylene blue, IMViC tests - Indole, Methyl Red, Voges Proskauer and Citrate Utilization Tests, MIC - Minimum inhibitory concentration.     

Annual gametogenic cycle of the freshwater pearl mussel,Lamellidens marginalis (Lamarck, 1819) collected from a perennial lentic habitat of Bangladesh

ABSTRACT

We investigated the annual gametogenic phenology of the freshwater pearl mussel, Lamellidens marginalis (Lamarck, 1819), collected from a lentic habitat at Mymensingh, Bangladesh, using biometry and histology through monthly sampling from August 2015 to July 2016. After biometric measurements, thin slices of dorso-ventral sections were cut from the middle of the mussels for histology to determine sex and level of gonadal maturation. The condition index (CI) ranged from 0.64 (March) to 0.99 (January) over the study period. The CI peaked three times (January, April and July) indicating that the mussels were ripe during these months and subsequent decreases in CI indicated spawning, which was consistent with histology. Both males and females exhibited similar patterns in terms of gonadal development, maturation and spawning activity. It was confirmed that natural populations of L. marginalis spawn throughout the year with remarkable temporal variations, except during December when the surface water temperature reaches annual minima (16.5°C). Highest spawning activity of L. marginalis was noted during February–March, May and July–November. The data obtained in the present study could be useful for the conservation managers of this commercial species by allowing harvesting of better quality mussels to be timed without interrupting major spawning activity.     

Diversity,abundance, and possible sources of fecal bacteria in the Yangtze River

The fecal bacteria in natural waters may pose serious risks on human health. Although many source tracking methods have been developed and used to determine the possible sources of the fecal pollution, little is known about the overall diversity and abundance of fecal bacterial community in natural waters. In this study, a method based on fecal bacterial sequence library was introduced to evaluate the fecal bacterial profile in the Yangtze River (Nanjing section). Our results suggested that the Yangtze River water harbors diverse fecal bacteria. Fifty-eight fecal operational taxonomic units (97% identity level) were detected in the Yangtze River water samples and the relative abundance of fecal bacteria in these samples ranged from 0.1 to 8%. It was also found that the relative abundances of the fecal bacteria in locations near to the downstream of wastewater treatment plants were obviously higher than those in other locations. However, the high abundance of fecal bacteria could decrease to the normal level in 2~4 km in the river due to degradation or dilution, and the overall fecal bacteria level changed little when the Yangtze River flew through the Nanjing City. Moreover, the fecal bacteria in the Yangtze River water were found to be highly associated (Spearman rho = 0.804, P < 0.001) with the potential pathogenic bacteria. Collectively, the findings in this study reveal the diversity, abundance, and possible sources of fecal bacteria in the Yangtze River and advance our understandings of the fecal bacteria community in the natural waters.

     

Modification of the standard most-probable-number procedure for fecal coliform bacteria in seawater and shellfish.

To determine whether or not presumptive tubes which take 48 h to become positive need to be transferred to EC medium during the fecal coliform multitube most-probable-number procedure, 572 seawater and shellfish samples were considered. When the 24-hour positive tubes alone were transferred to EC, it appeared that incorrect dilution data would be rare.     

Presence and sources of fecal coliform bacteria in epilithic periphyton communities of Lake Superior

Epilithic periphyton communities were sampled at three sites on the Minnesota shoreline of Lake Superior from June 2004 to August 2005 to determine if fecal coliforms and Escherichia coli were present throughout the ice-free season. Fecal coliform densities increased up to 4 orders of magnitude in early summer, reached peaks of up to 1.4x10(5) CFU cm-2 by late July, and decreased during autumn. Horizontal, fluorophore-enhanced repetitive-PCR DNA fingerprint analyses indicated that the source for 2% to 44% of the E. coli bacteria isolated from these periphyton communities could be identified when compared with a library of E. coli fingerprints from animal hosts and sewage. Waterfowl were the major source (68 to 99%) of periphyton E. coli strains that could be identified. Several periphyton E. coli isolates were genotypically identical (>or=92% similarity), repeatedly isolated over time, and unidentified when compared to the source library, suggesting that these strains were naturalized members of periphyton communities. If the unidentified E. coli strains from periphyton were added to the known source library, then 57% to 81% of E. coli strains from overlying waters could be identified, with waterfowl (15 to 67%), periphyton (6 to 28%), and sewage effluent (8 to 28%) being the major potential sources. Inoculated E. coli rapidly colonized natural periphyton in laboratory microcosms and persisted for several weeks, and some cells were released to the overlying water. Our results indicate that E. coli from periphyton released into waterways confounds the use of this bacterium as a reliable indicator of recent fecal pollution.     

A survey of the relative abundance of specific groups of cellulose degrading bacteria in anaerobic environments using fluorescence in situ hybridization

AIMS: The utility of fluorescence in situ hybridization (FISH) for detecting uncultured micro-organisms in environmental samples has been shown in numerous habitats. In this study a suite of three FISH probes for cellulolytic bacteria is described and their efficacy is demonstrated by quantifying the relative abundance of the target micro-organisms in a range of industrial biomass samples. METHODS AND RESULTS: The probes were designed from data derived from an artificial landfill leachate reactor study and 16S rRNA gene databases. The original biomass sample proved to be well described by the three probes targeting a total of 51% of the bacterial (EUBMIX targeted) cells in quantitative FISH experiments. CONCLUSIONS: Three probes were developed and applied to samples from a range of industrial digesters. The CSTG1244 probe, specific for organisms closely related to Clostridium stercorarium, were observed in the widest range of samples (7 of the 19 samples tested). The CTH216a FISH probe, specific for organisms closely related to Clostridium thermocellum, described the highest proportion of the bacterial population within any one sample (46% in an anaerobically digested sludge sample). Finally, the BCE216a probe, specific for organisms closely related to Bacteroides cellulosolvens, achieved the lowest level of hybridisation of the three probes tested. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that the three groups of anaerobic cellulolytic micro-organisms were present in different bioreactors but at variable abundances ranging from low (where other organisms would have been responsible for cellulolysis) to high. We showed the potential of using group specific FISH probes and quantitative FISH in environmental studies. The utility of using newly designed FISH probes was demonstrated by their ability to detect and quantify the target bacterial groups in samples from a range of industrial wastewater digesters.     

Incidence of R factors in coliform, fecal coliform, and Salmonella populations of the Red River in Canada.

Coliforms, fecal coliforms, and Salmonella were isolated from the Red River, Manitoba, Canada, and identified. These organisms were then examined for resistance to 12 antibiotics. Some fecal coliforms were resistant to all 12 antibiotics, and 18% of the Salmonella isolates were resistant to one or more antibiotics. A total of 52.9% of the fecal coliforms resistant to three or more antibiotics were able to transfer single or multiple resistance (R) determinants to the Salmonella recipient, and 40.7% could transfer R determinants to the Escherichia coli recipient. Of the resistant Salmonella, 57% transferred one or two determinants to the Salmonella recipient, and 39% transferred one or two determinants to the E. coli recipient. It was calculated that populations of fecal coliforms containing R factors were as high as 1,400 per 100 ml and that an accidental intake of a few milliliters of water could lead to transient or permanent colonization of the digestive tract. Consideration of data on bacteria with R factors should be made in future water quality deliberations and in discharge regulations.     

A preliminary study of fresh water fungi from Abaco Island,the Bahamas

Fresh water on a small marine island is rather limited and could be the habitat of aquatic fungi. Members of the Saprolegniales and Peronosporales can survive on organic matter found floating or submerged in shallow water. Recently a preliminary study was conducted on the keratinophilic fungi of Abaco Island, The Bahamas (5). The same island was surveyed for fresh water fungi in this investigation.     

Heavy metal pollution in surface water and sediment: A preliminary assessment of an urban river in a developing country

The concentration and chemical fractionation of globally alarming six heavy metals (Cr, Ni, Cu, As, Cd and Pb) were measured in surface water and sediment of an urban river in Bangladesh. The decreasing trend of metals were observed in water as Cr > Cu > As > Ni > Pb > Cd and in sediment as Cr > Ni > Cu > Pb > As > Cd. The level of studied metals exceeded the safe limits of drinking water, indicated that water from this river is not safe for drinking and/or cooking purposes. However, the investigated metals showed low mobility except for Cd and Pb which could pose a severe threat to the aquatic environment. Contamination factor (CF) and geoaccumulation index (I_geo) demonstrated that most of the sediment samples were moderately to heavily contaminated by Cr, As, Cd and Pb. The pollution load index (PLI) values were above one (>1) indicates progressive deterioration of the sediment quality. The extent of pollution by heavy metals in the river Korotoa implies that the condition is much frightening to the biota and inhabitants in the vicinity of the river as well.     

Diversity and abundance of ammonia-oxidizing archaea and bacteria in polluted mangrove sediment

Ammonia oxidation by microorganisms is a critical process in the nitrogen cycle. Recent research results show that ammonia-oxidizing archaea (AOA) are both abundant and diverse in a range of ecosystems. In this study, we examined the abundance and diversity of AOA and ammonia-oxidizing beta-proteobacteria (AOB) in estuarine sediments in Hong Kong for two seasons using the ammonia monooxygenase A subunit gene (amoA) as molecular biomarker. Relationships between diversity and abundance of AOA and AOB and physicochemical parameters were also explored. AOB were more diverse but less abundant than AOA. A few phylogenetically distinct amoA gene clusters were evident for both AOA and AOB from the mangrove sediment. Pearson moment correlation analysis and canonical correspondence analysis (CCA) were used to explore physicochemical parameters potentially important to AOA and AOB. Metal concentrations were proposed to contribute potentially to the distributions of AOA while total phosphorus (TP) was correlated to the distributions of AOB. Quantitative PCR estimates indicated that AOA were more abundant than AOB in all samples, but the ratio of AOA/AOB (from 1.8 to 6.3) was smaller than most other studies by one to two orders. The abundance of AOA or AOB was correlated with pH and temperature while the AOA/AOB ratio was with the concentrations of ammonium. Several physicochemical factors, rather than any single one, affect the distribution patterns suggesting that a combination of factors is involved in shaping the dynamics of AOA and AOB in the mangrove ecosystem.     

A simple bioluminescence procedure for early warning detection of coliform bacteria in drinking water

Traditional cultivation-dependent tests for coliform bacteria in food and drinking water take 18–24 h to complete. Bioluminescence-based enzyme assays can potentially reduce analysis time for indicator bacteria such as coliforms. In the present study, we developed a simple presence/absence (P/A) bioluminescence procedure for rapid detection of coliform bacteria in groundwater-based drinking water. The bioluminescence procedure targeting β-d-galactosidase activity in coliform bacteria was based on hydrolysis of 6-O-β-galactopyranosyl-luciferin. Bacteria immobilized on membrane filters were enriched for 6–8 h in selective media containing isopropyl-β-d-thiogalactopyranoside (IPTG) to induce β-d-galactosidase activity in coliform bacteria. The equivalent of approximately 300 E. coli cells was required for bioluminescence detection of β-d-galactosidase activity. In comparison, PCR based detection of E. coli in drinking water required approximately 30 target cells. Analysis of contaminated drinking water samples showed comparable results for coliform bacteria using traditional multiple-tube fermentation, Colilert-18, and the bioluminescence procedure. Aeromonas hydrophila or indigenous groundwater bacteria did not interfere with the procedure. The bioluminescence procedure can be combined with commercial substrates such as Fluorocult or Colilert-18, and will allow the detection of one coliform in 100 ml drinking water within one working day. The results suggest the bioluminescence assays targeting β-d-galactosidase activity may be used for or for early warning screening of drinking water and/or rapid identification of contaminated drinking water wells.     

Assessing noninvasive hair and fecal sampling for monitoring the distribution and abundance of river otter

Monitoring the distribution and abundance of populations is an important component of efforts to meet management or conservation goals. Although the objectives for such studies are easy to define, cost-effective, precise, and accurate estimates are often elusive. We tested the efficacy and compared the cost-effectiveness of methods for estimating the number and recording the distribution of river otter (Lontra canadensis). We genotyped otter hair sampled using two noninvasive instruments and compared those results with a hypothetical study design based on DNA extracted from fecal matter. Patterns of distribution generated from DNA collected at latrine sites were then compared to observations of otter collected using VHF radiotelemetry. We achieved a high probability of genotyping river otter with a small number of hairs (i.e., 59.0 % probability of producing a genotype with 1 guard hair and >5 under hair samples) collected using wire body snares and knaplock hair snags. Body snares were more effective at collecting otter hair, but there was relatively little additional cost to using both sampling instruments. Genotyped hair resulted in a high multi-year recapture rate (61.9 %). Hair collection and genotyping was the most cost-effective method for monitoring populations of river otter ($168.50 US/datum) followed by radiotelemetry ($264.50 US/datum), and the extraction of DNA from fecal matter ($266.00 US/datum). However, the noninvasive techniques did not represent the full distribution and fine-scale movements of otter, as observed using radiotelemetry. There has been much recent reporting of the efficacy of fecal matter as a source of DNA for conducting mark–recapture population estimates for mesocarnivores. Our data suggested that collecting DNA in hair may be a more cost-effective and efficient approach.     

A note on the enumeration of manganese-oxidizing bacteria in estuarine water and sediment samples

V ojak , P.W.L., E dwards , C. & J ones , M.V. 1985. A note on the enumeration of manganese-oxidizing bacteria in estuarine water and sediment samples. Journal at Applied Bacteriology 59, 375–379.
Media for the enumeration of manganese-oxidizing bacteria in estuarine water and sediment samples were compared. A peptone/yeast extract medium containing manganese sulphate and 30% (v/v) sea salts solution gave the highest percentage of manganese-oxidizers and high total viable counts. A survey of estuarine (River Tamar) and marine (English Channel) sites indicated that manganese-oxidizing bacteria comprise a significant but variable proportion (11–85%) of the total bacterial count.     

Detection of coliform bacteria in water by polymerase chain reaction and gene probes

Polymerase chain reaction (PCR) amplification and gene probe detection of regions of two genes, lacZ and lamB, were tested for their abilities to detect coliform bacteria. Amplification of a segment of the coding region of Escherichia coli lacZ by using a PCR primer annealing temperature of 50 degrees C detected E. coli and other coliform bacteria (including Shigella spp.) but not Salmonella spp. and noncoliform bacteria. Amplification of a region of E. coli lamB by using a primer annealing temperature of 50 degrees C selectively detected E. coli and Salmonella and Shigella spp. PCR amplification and radiolabeled gene probes detected as little as 1 to 10 fg of genomic E. coli DNA and as a few as 1 to 5 viable E. coli cells in 100 ml of water. PCR amplification of lacZ and lamB provides a basis for a method to detect indicators of fecal contamination of water, and amplification of lamB in particular permits detection of E. coli and enteric pathogens (Salmonella and Shigella spp.) with the necessary specificity and sensitivity for monitoring the bacteriological quality of water so as to ensure the safety of water supplies.