Microbial degradation of organochlorine pesticide: 2,4-Dichlorophenoxyacetic acid by axenic and mixed consortium.

The presence of 2,4-dichlorophenoxyacetic acid (2,4-D), an organochlorine herbicide, in the environment has raised public concern as it poses hazard to both humans and the ecosystem. Three potential strains having the capability to degrade 2,4-D were isolated from on site agricultural soil and identified as Arthrobacter sp. SVMIICT25, Sphingomonas sp. SVMIICT11 and Stenotrophomonas sp. SVMIICT13. Over 12 days of incubation, 81-90% of 100 mg/L of 2,4-D degradation was observed at 2% inoculum. A shorter lag phase with 80% of degradation efficiency was observed within 5 days when the inoculum size was increased to 10%. Six microbial consortia were prepared by combining the isolates along with in-house strains, Bacillus sp. and Pseudomonas sp. Consortia R3 (Arthrobacter sp. + Sphingomonas sp.), operated with 10% of inoculum, showed 85-90% degradation within 4 days and 98-100% in 9 days. Further, targeted exo-metabolite analysis confirmed the presence and catabolism of intermediate 2,4-dichlorophenol and 4-chlorophenol compounds.

Critical factors influence on acidogenesis towards volatile fatty acid, biohydrogen and methane production from the molasses-spent wash.

The study explored the spent wash valorisation into value added biobased products viz. volatile fatty acids (VFAs), biohydrogen (bio-H2), methane (CH4) and biohythane (bio-H-CNG) based on eight selected parameters employing design of experiment (DOE) approach. Selectively enriched biocatalyst showed marked influence on the production of acidogenic products (bio-H2 and VFA) while untreated inoculum resulted in higher CH4 and bio-H-CNG generation. CaCO3 showed potential for butyric acid (HBu) production while Na2CO3 specifically yielded higher acetic acid (HAc) when supplemented as buffering agents. Higher degree of acidification (DOA; 49.8%) was observed at lower organic load (OL; 30 g/L). Biogas production and profile was influenced by OL, enrichment of biocatalyst and supplemented buffering agent. Higher OL related to higher bioproduct production, while yields of the respective products were higher at lower OL.

Anodic metabolic activity regulates the desalination efficiency in microbial catalysed electrochemical system.

Anodic metabolic rate showed regulatory influence on the desalination performance of microbial desalination cell (MDC) under open (OC) and closed circuit (CC) operations. In this study, three MDCs were tested for desalination with three different organic substrate loads 1500 ± 55 mg/L in MDC-A; 3500 ± 10 g/L in MDC-B; 4500 ± 12 g/L in MDC-C. Higher desalination and substrate removal rates were observed in CC than OC. Average desalination was MDC-C (51.4%-CC) > MDC-B (47.3%-CC) > MDC-A (45.3%-CC) and COD removal efficiencies were MDC-C (68.4%-CC) > MDC-B (64.4%-CC) > MDC-A (51.9%-CC). Increase in organic load resulted in higher desalination efficiency which was due to higher electrochemical and ionic gradient apart from anodic metabolic activity. The voltage and current density were observed to be maximum in MDC-C (685 mV; 2.16 mA/m2) followed by MDC-B (598 mV; 1.98 mA/m2) and MDC-A (501 mV; 1.76 mA/m2). This study demonstrated that the MDCs performance can be regulated by varying organic load and circuitry modes.