Towards enhancement of fungal hydrolytic enzyme cocktail using waste algal biomass of Oscillatoria obscura and enzyme stability investigation under the influence of iron oxide nanoparticles.

Development of low-cost and economic cellulase production is among the key challenges due to its broad industrial applications. One of the main topics of research pertaining to sustainable biomass waste based biorefinaries is the development of economic cellulase production strategies. The main cause of the increase in cellulase production costs is the use of commercial substrates; as a result, the cost of any cellulase-based bioprocess can be decreased by employing a productive, low-cost substrate. The goal of the current study is to develop low-cost cellulase using the carbohydrate-rich, renewable, and widely accessible cyanobacteria algae Oscillatoria obscura as the production substrate. Maximum cellulase was produced utilising the fungus Rhizopus oryzae at substrate concentration of 7.0 g among various tested concentrations of algal biomass. Maximum production rates of 22 IU/gds FP, 105 IU/gds BGL, and 116 IU/gds EG in 72 h were possible under optimal conditions and substrate concentration. Further investigations on the crude enzyme's stability in the presence of iron oxide nanoparticles (IONPs) revealed that it was thermally stable at 60 °C for up to 8 h. Additionally, the crude enzyme demonstrated pH stability by maintaining its complete activity at pH 6.0 for 8 h in the presence of the optimal dose of 15 mg IONPs. The outcomes of this research may be used to investigate the possibility of producing such enzymes in large quantities at low cost for industrial use.

Improved biohydrogen production via graphene oxide supported granular system based on algal hydrolyzate, secondary sewage sludge and bacterial consortia.

Biohydrogen production using renewable sources has been regarded as one of the most sustainable ways to develop low-cost and green production technology. In order to achieve this objective, herein biohydrogen production has been conducted using the combination of untreated secondary sewage sludge (Sss), algal biomass hydrolyzate (Abh), graphene oxide (GO) and bacterial consortia that forms a granular system. Thus, naturally formed granular system produced cumulative H2 of 1520 mL/L in 168 h with the maximum production rate of 13.4 mL/L/h in 96 h at initial pH 7.0, and optimum temperature of 37 °C. It is noticed that the combination of Abh, Sss and GO governed medium showed 42.05 % higher cumulative H2 production along with 22.71 % higher production rate as compared to Abh and Sss based H2 production medium. The strategy presented herein may find potential applications for the low-cost biohydrogen production using waste biomasses including Sss and Abh.

Co-fermentation of residual algal biomass and glucose under the influence of Fe3O4 nanoparticles to enhance biohydrogen production under dark mode.

The present study reports Fe3O4 nanoparticles (Fe3O4 NPs) induced enhanced hydrogen production via co-fermentation of glucose and residual algal biomass (cyanobacteria Lyngbya limnetica). A significant enhancement of dark fermentative H2 production has been noticed under the influence of co-fermentation of glucose and residual algal biomass using Fe3O4 NPs as catalyst. Further, using the optimized ratio of glucose to residual algal biomass (10:4), ∼ 37.14 % higher cumulative H2 has been recorded in presence of 7.5 mg/L Fe3O4 NPs as compared to control at 37 °C. In addition, under the optimum conditions [glucose to residual algal biomass ratio (10:4)] presence of 7.5 mg/L Fe3O4 NPs produces âˆ¼ 937 mL/L cumulative H2 in 168 h at pH 7.5 and at temperature 40 °C. Clostridum butyrium, employed for the dark fermentation yielded âˆ¼ 7.7 g/L dry biomass in 168 h whereas acetate (9.0 g/L) and butyrate (6.2 g/L) have been recorded as the dominating metabolites.

Growth of Cyanobacteria: Optimization for Increased Carbohydrate Content.

Growths of Lyngbya limnetica and Oscillatoria obscura were investigated at varying pH, light intensity, temperature, and trace element concentration with a view to optimize these parameters for obtaining the maximum carbohydrate content. The maximum growth for both strains was obtained at pH 9.0 and temperature 20 ± 3 °C using a light intensity of 68.0 µmol m-2 s-1 with continuous shaking. Growth under the nitrogen starvation condition affected the carbohydrate content more compared to the phosphorus starvation, and maximum concentrations were found as 0.660 and 0.621 g/g of dry biomass for L. limnetica and O. obscura, respectively. Under the optimized nitrogen-rich conditions, the specific growth rates for the two strains were found to be 0.187 and 0.215 day-1, respectively. The two-stage growth studies under nitrogen-rich (stage I) followed by nitrogen starvation (stage II) conditions were performed, and maximum biomass and carbohydrate productivity were found as 0.088 and 0.423 g L-1 day-1 for L. limnetica. This is the first ever attempt to evaluate and optimize various parameters affecting the growth of cyanobacterial biomass of L. limnetica and O. obscura as well as their carbohydrate contents.

Efficient dark fermentative hydrogen production from enzyme hydrolyzed rice straw by Clostridium pasteurianum (MTCC116).

In the present work, production of hydrogen via dark fermentation has been carried out using the hydrolyzed rice straw and Clostridium pasteurianum (MTCC116). The hydrolysis reaction of 1.0% alkali pretreated rice straw was performed at 70°C and 10% substrate loading via Fe3O4/Alginate nanocomposite (Fe3O4/Alginate NCs) treated thermostable crude cellulase enzyme following the previously established method. It is noticed that under the optimized conditions, at 70°C the Fe3O4/Alginate NCs treated cellulase has produced around 54.18g/L sugars as the rice straw hydrolyzate. Moreover, the efficiency of the process illustrates that using this hydrolyzate, Clostridium pasteurianum (MTCC116) could produce cumulative hydrogen of 2580ml/L in 144h with the maximum production rate of 23.96ml/L/h in 96h. In addition, maximum dry bacterial biomass of 1.02g/L and 1.51g/L was recorded after 96h and 144h, respectively with corresponding initial pH of 6.6 and 3.8, suggesting higher hydrogen production.