Gene Regulation of Biofilm-Associated Functional Amyloids.

Biofilms are bacterial communities encased in a rigid yet dynamic extracellular matrix. The sociobiology of bacterial communities within a biofilm is astonishing, with environmental factors playing a crucial role in determining the switch from planktonic to a sessile form of life. The mechanism of biofilm biogenesis is an intriguingly complex phenomenon governed by the tight regulation of expression of various biofilm-matrix components. One of the major constituents of the biofilm matrix is proteinaceous polymers called amyloids. Since the discovery, the significance of biofilm-associated amyloids in adhesion, aggregation, protection, and infection development has been much appreciated. The amyloid expression and assembly is regulated spatio-temporarily within the bacterial cells to perform a diverse function. This review provides a comprehensive account of the genetic regulation associated with the expression of amyloids in bacteria. The stringent control ensures optimal utilization of amyloid scaffold during biofilm biogenesis. We conclude the review by summarizing environmental factors influencing the expression and regulation of amyloids.

Enhancing biomethanation from dairy waste activated biomass using a novel EGTA mediated microwave disintegration.

A novel approach to explore the impact of calcium specific chelant - Ethylene glycol tetra acetic acid (EGTA) on deflocculation followed by biomass disintegration using microwave (MW) was investigated. In the first phase of the study, the EGTA dosage of 0.012 g/g suspended solids (SS) was found to be optimal for disassociating the biomass. Subsequent disintegration of biomass in microwave (EGTA-MW) yielded a biomass lysis and solids reduction of about 39.7% and 30.5%. EGTA-MW disintegration reduces the amount of specific energy required to disintegrate the biomass from 18,900 kJ/kg TS to 13,500 kJ/kg TS, when compared to control. The impact of EGTA-MW disintegration on anaerobic digestion was also evident from its methane yield (235.3 mL/g VS) which was 36.2% higher than control. An economic assessment of this study provides a net profit of 8.48 €/ton in EGTA-MW and highly endorsed for biomass disintegration.

H2O2 induced cost effective microwave disintegration of dairy waste activated sludge in acidic environment for efficient biomethane generation.

This study aimed to improve the biomethane potential of dairy waste activated sludge (WAS) by H2O2-acidic pH induced microwave disintegration (HAMW-D) pretreatment approach. The results of HAMW-D compared with the microwave disintegration (MW-D) alone for energy and economic factors. In the two phase disintegration process, the H2O2 concentration of about 0.5mg/g SS under acid pH of 5 was found to be optimum for effective dissociation of Extracellular Polymeric Substances (EPS) matrix. A higher liquefaction of about 46.6% was achieved in HAMW-D when compared to that of MW-D (30%). It subsequently improved the methane yield of about 250mL/g VS in HAMW-D, which was 9.6% higher than MW-D. A net profit of about 49€/ton was achieved for HAMW-D, therefore it is highly recommended for WAS pretreatment.

Effect of concentration of trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ) silylating agents on surface free energy of silica aerogels.

The surface free energy of a solid determines its surface and interfacial behavior in processes like wetting and adhesion which is crucial for silica aerogels in case of organic liquid absorption and transportation of chemicals at nano-scale for biotechnological applications. Here, we have demonstrated that the surface free energy of aerogels can be tuned in wide range from 5.5892 to 0.3073 mJ/m(2) by modifying their surface using TMCS and HMDZ silylating reagents. The alcogels were prepared by two step acid-base catalyzed process where the molar ratio of precursors Tetraethoxysilane (TEOS):Methanol (MeOH):Oxalic acid:NH(4)OH:NH(4)F was kept at optimal value of 1:2.7:0.18×10(-4):0.02:0.22×10(-3), respectively. To modify gel surfaces, TMCS and HMDZ concentration have been varied from 3% to 12% and such alcogels were dried at ambient pressure. It is observed from FTIR for aerogels that increase in concentration of silylating reagent resulted increase in hydrophobicity. This leads to increase in contact angle for water from 123° to 155° but leads to decrease in surface free energy from 5.5892 to 0.3073 mJ/m(2). As there is not direct method, we have used Neumann's equation of state to estimate surface energy of aerogels.