Probiotic Characterization of Arsenic-resistant Lactic Acid Bacteria for Possible Application as Arsenic Bioremediation Tool in Fish for Safe Fish Food Production.

Arsenic (As) contamination of water and food is a global problem posing a severe threat to environmental and human health; therefore, fish as an aquatic animal is immensely affected by the hazardous impacts of As. The present study aimed to explore the As-resistant probiotic bacteria and characterize their potential for applying as an As bioremediation tool in fish. As-resistant lactic acid bacteria (LAB) were isolated from sludge samples of an old stabilization pond/lagoon of wastewater treatment plant using spared plate techniques. The potential probiotic was selected by assessing the sequential probiotic characterization, As resistance and removal properties. The selected probiotic was identified by PCR-based molecular method using 16S rDNA. A total of 51 As-resistant LAB were isolated from sludge samples. Potential six As-resistant LAB strains (As4, 11, 20, 21, 41 and 48) were selected from 51 isolates through sequential probiotic characterizations using mimic fish gastrointestinal conditions. The selected probiotics displayed relatively elevated As (> 1000 mg L-1), cadmium (20-100 mg L-1) and lead (> 2000 mg L-1)-resistant patterns and excellent As-removal efficiencies (0.0012-0.0044 mg As mg cell-1 h-1) from water along with favourable various associative probiotic properties. The 16S rDNA sequence-based molecular identification and phylogenetic analysis revealed that the strains As4, 11, 20, 21, 41 and 48 belong to Limosilactobacillus fermentum (Lactobacillus fermentum according to old taxonomy). The As removal and survival in mimic gastrointestinal conditions of fish indicated that new Limosilactobacillus fermentum strains could be employed as the novel and potential probiotic tools for possible bioremediation of As and other pollutants in the fish to prevent the bioaccumulation and toxicity impacts of As in fish for cleaner and safe fish food production.

Assessing the cellulase enzyme heterogeneity of bacterial strains and their feedback to cattle manure degradation in a greenhouse model of in vivo pond ecosystem.

The responses of cellulase enzymes of three bacterial isolates and their impacts on cattle manure decomposition were assessed in a greenhouse model in vivo pond ecosystem. Fifty grams of fresh cattle manure was placed in a fastened nylon bag (mesh size ~ 50 µm dia.) and placed in triplicate in a plastic bucket with 10 l of pond water which was hung inside the enclosed polyhouse, semi-closed and open systems for 4 weeks. Samples of manure residue directly from nylon bag and water from manure leached bucket water, water, and soil from the enclosed polyhouse were collected for enzymatic assays, enumeration of aerobic cellulose decomposing and heterotrophic bacteria, and determination of water and soil quality parameters. Responses of cellulases to different temperatures in situ were also elucidated. The values of test bacteria, endoglucanase, exoglucanase and ß-glucosidase, and organic carbon were significantly (P Ë‚ 0.05) higher in the closed system compared to semi-closed or open system. Priming of all the enzymes coupled with the peak of aerobic cellulose decomposing bacteria and heterotrophic bacterial populations occurred on the day 14 or 21 in vivo. Since the peaks of three cellulases of bacterial isolates (KUPH1, KUPH6, and KUPH8) were demonstrated between 35 and 40 °C, and that temperature coincided with temperature of the greenhouse model, this temperature range appeared to favor the growth of cellulose decomposing bacterial populations and involved cellulase enzymes.

Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration-A Long Term Field Test Conducted in West Bengal.

Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved-without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.

Storage induced changes in coliform, heterotrophic groups of bacteria and nutrient levels of human urine for its safe use in biological production.

Human urine is a potential source of various nutrients, minerals and trace elements. Its use as a fertilizer is growing popular among farmers. Here, we examined the pattern of changes in the counts of coliform, heterotrophic bacteria as well as physico-chemical characteristics of human urine during different days of storage under closed conditions at ambient temperature. We observed that after 253 days of storage under closed condition, the coliform counts were reduced significantly and remained within the safe limit to be used as fertilizer. With increase in storage period, the concentration of phosphate showed decline coupled with rise in pH, alkalinity and electrical conductance. Our study revealed that human urine can be used as safe fertilizer after 8 months of storage under closed conditions at ambient temperature ranging 25-35ºC.

Cadmium tolerance and antibiotic resistance in Escherichia coli isolated from waste stabilization ponds.

The incidence pattern of cadmium tolerance and antibiotics resistance by Escherichia coli was examined periodically from the samples of water, sludge and intestine of fish raised in waste stabilization ponds in a sewage treatment plant. Samples of water and sludge were collected from all the selected ponds and were monitored for total counts of fecal coliform (FC), total coliform (TC) and the population of Escherichia coli, which was also obtained from the intestine of fishes. Total counts of both FC and TC as well as counts of E. coli were markedly reduced from the facultative pond to the last maturation pond. Tolerance limit to cadmium by E. coli tended to decline as the distance of the sewage effluent from the source increased; the effective lethal concentration of cadmium ranged from 0.1 mM in split chamber to 0.05 mM in first maturation pond. E. coli isolated from water, sludge and fish gut were sensitive to seven out of ten antibiotics tested. It appears that holistic functions mediated through the mutualistic growth of micro algae and heterotrophic bacteria in the waste stabilization ponds were responsible for the promotion of water quality and significant reduction of coliform along the sewage effluent gradient.