Immobilization of Halomonas halodurans and Bacillus halodurans in packed bed bioreactor for continuous removal of phenolic impurities in waste water.

Phenol is an organic contaminant widely distributed in wastewater. Biodegradation is one of the suitable methods used to remove phenol from the wastewater. In this study, the bacterial laccase and pectinase were analyzed and phenol degradation potential was studied. A total of six bacterial strains were selected and their phenol degrading potentials were studied. Laccase and pectinase producers were screened on substrate agar plates and several strains produced these enzymes in submerged fermentation. Among these enzyme producing strains, strain PD8 and PD22 exhibited potent phenol degrading ability than other strains. These two bacterial strains (Halomonas halodurans PD8 and Bacillus halodurans PD22) exhibited maximum growth in phenol-supplemented culture medium. These two organisms grown well at wide pH values (pH 3.0 and 10.0), survive well between 20 °C and 50 °C, and showed growth between 1 and 10% sodium chloride concentration. The lyophilized enzyme from PD8 and PD22 were immobilized with alginate beads cross liked with divalent cations. At 1% alginate, the binding efficiency was 40.2 ± 2.9% and it improved up to 2.0% concentration (67.5 ± 4.2%) and further increase on alginate concentration affected binding efficiency. Phenol degradation was maximum within 10 h of treatment in the immobilized packed bed column reactor (83.1 ± 3.2%) and colour removal efficiency was maximum at 12 h treatment (82.1 ± 3.9%). After four successive experimental trials more than 40% efficiency was achieved.

Biocatalytic degradation of organophosphate pesticide from the wastewater and hydrolytic enzyme properties of consortium isolated from the pesticide contaminated water.

The indiscriminate application of various pesticides leads to toxicity to the humans, animals, fishes and threatens the environment and ecosystem. The present study was aimed to investigate pesticide degrading bacteria from the pesticide contaminated sample and to localize organophophate hydrolase activity from the bacteria. Sediment sample was selected as the source of microorganism for the degradation of chlorpyrifos. Enterobacter aerogenes CP2 and Streptococcus pyogenes CP11 isolated from the contaminated sample removed 77 ± 1.8%, 74.2 ± 3.1 chlorpyrifos. These strains have the potential to utilize pesticide as the source of carbon and energy. The pesticides inoculated with both CP 2 and CP 11 enhanced biodegradation of chlorpyrifos at optimized condition. E. aerogenes CP2 and S. pyogenes CP11 produced organophosphate hydrolase activity and localized enzyme biosynthesis. Organophosphate hydrolase activity was high in intracellular, followed by outer membrane and extracellular sample for both bacteria. The treated wastewater has no impact on the seed germination indicated normal cell division, cell elongation and indole-3 acetic acid synthesis. The strain CP2 has the rapid rate of organophosphate degradation among Enterobacter species.

Effective removal of pharmaceutical impurities and nutrients using biocatalyst from the municipal wastewater with moving bed packed reactor.

The presence of antibiotics in the wastewater is one of the important issues related to environmental management. In this study, antibiotics-degrading bacteria were screened from the enriched sewage sludge sample. Among the isolated bacterial strains, Bacillus subtilis AQ03 showed maximum antibiotic tolerance (>2000 ppm). The characterized strain B. subtilis AQ03 degraded sulfamethaoxazole and sulfamethoxine and the optimum nutrient and physical-factors were analyzed. B. subtilis AQ03 degraded 99.8 ± 1.3 % sulfamethaoxazole, and 93.3 ± 6.2 % sulfamethoxine. Sodium nitrate and ammonium chloride were improved antibiotics degradation (<90 %). The optimized conditions were maintained in a moving bed bioreactor for the removal of antibiotics and nutrients from the wastewater. The selected strain considerably produced proteases (109.4 U/mL), amylases (55.1 U/mL), cellulase (9.6 U/mL) and laccases (15.2). In moving bed reactor, sulfamethaoxazole degradation was maximum after 8 days (100 ± 1.5 %) and sulfamethoxazole (100 ± 0) was removed completely from wastewater after 10 days. In moving bed reactor, biological oxygen demand (92.1 ± 2.8 %), chemical oxygen demand (79.6 ± 1.2 %), nitrate (89.4 ± 3.9 %) and phosphate (91.8 ± 1.2) were removed from the wastewater along with antibiotics after 10 days of treatment. The findings indicate that the indigenous bacterial communities and the ability to survive in the presence of high antibiotic concentrations and xenobiotics. Moving bed bioreactor is useful for the removal of nutrients and antibiotics from wastewater.

Dye degradation, antimicrobial and larvicidal activity of silver nanoparticles biosynthesized from Cleistanthus collinus.

The present study aimed in green synthesis and characterization of silver nanoparticles (AgNPs) using the leaves of Cleistanthus collinus. The NPs showed various absorption peaks between 3402 cm-1 and 1063 cm-1. FTIR spectrum revealed the presence of OH group, alkene, aromatic hydrocarbon, aliphatic fluro compound and aliphatic chloro compounds. Scanning electron microscopic analysis revealed the particle size ranged from 30 to 50 nm. The biosynthesized NPs have potent activity against Shigella dysentriae, Staphylococcus aureus and Bacillus subtilis and the zone of inhibition was 21 ± 1, 20 ± 2, 16 ± 2 mm, respectively. Toxicity of the synthesized NPs was tested on green gram (Vigna radiata) seed at various concentrations (20-100%) and germination was induced by NPs treated seeds. Shoot length and root length was higher in NPs treated plant than control plant (p < 0.01). Elevated level of catalase (CAT) and superoxide dismutase (SOD) and about 13% CAT and 7% SOD activity registered than control. Superoxide dismutase activity of root and shoot varied based on the dosage of AgNPs (p < 0.01). Also, the NPs (1%) showed significant larvicidal activity on Aedes aegypti and 100% mortality was achieved after 24 h treatment. The green synthesized NPs reduced methylene blue and 4-nitrophenol significantly (p < 0.01). The colouration of methylene blue and 4-nitrophenol were considerably reduced after 60 min showed the potential of dye degrading ability.

Cleistanthus collinus poisoning affects mitochondrial respiration and induces oxidative stress in the rat kidney.

Cleistanthus collinus is a poisonous shrub used for deliberate self-harm in rural areas of South India and intake of boiled decoction of leaves is a common method of self-harm. Distal renal tubular acidosis (dRTA) is an important clinical symptom observed in C. collinus poisoning, and renal V-ATPases may be potential targets of damage. However, a lack of understanding of molecular mediators involved hampers medical management, which is mainly supportive. We hypothesized that C. collinus poisoning induces renal oxidative stress; probably by inducing mitochondrial uncoupling, which compromises V-ATPase activity to ultimately produce dRTA. This was tested by exposing renal BBMV, kidney cells in culture, and Wistar rats to C. collinus poisoning. Exposure to C. collinus aqueous extract resulted in significant elevations in the lipid peroxidation marker, conjugated dienes, in cell culture and in vivo. A significant decrease in mitochondrial respiratory control ratio was observed in kidneys from C. collinus-treated animals suggesting that mitochondrial oxidative phosphorylation is uncoupled. This was accompanied by significant increase in ADP levels and a decrease in proton pump activity. Thus, these results demonstrate that C. collinus poisoning induces oxidative stress which influences proton pump activity, probably due to feedback inhibition by elevated ADP levels because of mitochondrial dysfunction in the rat kidney.

Mechanisms of toxicity of Cleistanthus collinus: vacuolar ATPases are a putative target.

Ingestion of Cleistanthus collinus, a shrub native to South India, either intentionally or accidentally, is a common cause of death in the area. Consumption of a boiled decoction of leaves is highly toxic, but medical management of patients is mainly supportive because the molecular mechanisms of toxin action are unknown. Distal renal tubular acidosis is one of the symptoms of poisoning in patients and adenosine triphosphate (ATP) requiring proton pumps is important for acid secretion in the kidney. Hence, we hypothesized that these may be putative targets for C. collinus action and we tested this by exposing rat renal brush border membrane (BBM) as well as cultured kidney cells to a boiled decoction of C. collinus. Exposure to the C. collinus decoction resulted in significant inhibition of vacuolar type H(+)-ATPase (V-ATPase) activity in renal BBM as well as blocking of the proton pump in renal BBM vesicles. C. collinus decoction was also found to inhibit acidification of intracellular organelles in cells in culture, similar to the effect seen with either bafilomycin or concanamycin - specific inhibitors of the V-ATPase. This was accompanied by a decrease in V-ATPase activity, but an increase in protein levels. These results demonstrate that the V-ATPase in renal cells is a putative target for the toxins in C. collinus and the inhibition of this important proton pump probably plays a role in the development of distal renal tubular acidosis and subsequent renal failure seen in poisoned patients.