Senigala K Jayalakshmi’s research while affiliated with University of Agricultural Sciences Raichur and other places

In the present context, we have assessed the green approach for the extraction of phenolics from agro-residues of rice viz., rice bran, and rice straw using water as an extracting solvent. The extraction was optimized with respect to time, temperature, pH, and solid (agro-residues) to liquid (water) ratio. The hydrolysates obtained were determined for phenolics and their antioxidant activities. The maximum total phenolic content (61.32 mg/100 g GAE), flavonoid content (13.19 mg/ 100 g QE), and tannin content (58.33 mg/100 g TAE) were obtained for rice bran followed by rice straw at pH 5, 1:20 (solid: liquid) for 10 min of extraction. Also, higher antioxidant properties (78.03% for DPPH, 86.45% for ABTS, and 0.85 absorbance at 700 nm for FRAP) were observed for the extracts of rice bran. Caffeic acid, gallic acid, p-coumaric acid, syringic acid, ferulic acid, 2,5-dihydroxy benzoic acid, kaemferol, quercetin, and epicatechin were analyzed by HPLC in both the rice biomass used. This study significantly converts rice biomass to antioxidative phenolic compounds under simple extraction conditions favoring the waste management process and also adding value to the waste biomass.

In the present context, we have assessed the green approach for the extraction of phenolics from agro-residues of rice viz., rice bran, and rice straw using water as an extracting solvent. The extraction was optimized with respect to time, temperature, pH, and solid (agro-residues) to liquid (water) ratio. The hydrolysates obtained were determined for phenolics and their antioxidant activities. The maximum total phenolic content (61.32 mg/100 g GAE), flavonoid content (13.19 mg/ 100 g QE), and tannin content (58.33 mg/100 g TAE) were obtained for rice bran followed by rice straw at pH 5, 1:20 (solid: liquid) for 10 min of extraction. Also, higher antioxidant properties (78.03% for DPPH, 86.45% for ABTS, and 0.85 absorbance at 700 nm for FRAP) were observed for the extracts of rice bran. Caffeic acid, gallic acid, p-coumaric acid, syringic acid, ferulic acid, 2,5-dihydroxy benzoic acid, kaemferol, quercetin, and epicatechin were analyzed by HPLC in both the rice biomass used. This study significantly converts rice biomass to antioxidative phenolic compounds under simple extraction conditions favoring the waste management process and also adding value to the waste biomass.

Purpose This study focuses to assess the potentiality of the locally isolated Burkholderia sp SMB1. It was aimed for the cocktail of lignocellulolytic enzymes production involved in the depolymerization of the agro-wastes to release sugars for bioethanol production. Methods The optimization of enzymes cocktail (lignolytic, cellulolytic, hemicellulolytic) production by isolated bacterium utilizing inexpensive substrates like bran and straw of rice was done using response surface methodology. Further this cocktail secreted by the bacterium at optimized conditions was employed for saccharifying untreated agro-wastes for sugars production which were fermented to bioethanol by S. cerevisiae. Results This strain produced high titer of cellulase (10.8 U/mL), xylanase (76 U/mL), mannanase (14.23 U/mL), pectinase (62.18 U/mL) and laccase (24.25 U/mL) using rice bran at 7 pH and 40 °C using 10% (w/v) of rice bran. The production of cocktail of enzymes was slightly increased by adding CaCO3 (2mM) in the growth medium. This cocktail was able to hydrolyze untreated agro-wastes to release highest reducing sugars 28.5 g/L using untreated corn husk after 24 h of saccharification process. These sugars of corn husk were fermented by S. cerevisiae to produce highest 9.04 g/L bioethanol. Conclusions This paper represents the exploitation of the locally isolated strain for the production of lignocellulolytic enzymes using rice bran and straw for the first time promising the significance of the study. This study helps in waste disposal process by valorizing the waste biomass to produce value added products like sugars, bioethanol and hence increases agricultural economy. Graphic Abstract

Purpose: This study focuses to assess the potentiality of the locally isolated Burkholderia sp SMB1. It was aimed for the cocktail of lignocellulolytic enzyme production involved in the depolymerization of the agro-wastes to release sugars for bioethanol production. Methods: The optimization of enzyme cocktail (lignolytic, cellulolytic, hemicellulolytic) production by isolated bacterium utilizing inexpensive substrates like bran and straw of rice was done using response surface methodology. Further this cocktail secreted by the bacterium at optimized conditions was employed for saccharifying untreated agro-wastes for sugars production which were fermented to bioethanol by S. cerevisiae. Results: This strain produced high titer of cellulase (10.8 U/mL), xylanase (76 U/mL), mannanase (14.23 U/mL), pectinase (62.18 U/mL) and laccase (24.25 U/mL) using rice bran at 7 pH and 40 oC using 10% (w/v) of rice bran. The production of cocktail of enzymes was slightly increased by adding CaCO3 (2mM) in the growth medium. This cocktail was able to hydrolyze untreated agro-wastes to release highest reducing sugars 28.5 g/L using untreated corn husk after 24 h of saccharification process. These sugars of corn husk were fermented by S. cerevisiae to produce highest 9.04 gL⁻¹ bioethanol. Conclusion: This paper represents the exploitation of the locally isolated strain for the production of lignocellulolytic enzymes using rice bran and straw for the first time promising the novelty of the study. This study helps in waste disposal process by valorizing the waste biomass to produce value added products like sugars, bioethanol and hence increases agricultural economy.

An extracellular laccase enzyme secreted from Sphingobacterium ksn-11 was purified to electrophoretic homogeneity, showing a molecular weight of 90 kDa. The purified enzyme was monomeric in nature confirmed by sodium dodecyl gel electrophoresis. The optimum temperature and pH were found to be 40 °C and 4.5 respectively. The enzyme showed highest substrate specificity for 2,2 azino-bis (ethylthiozoline-6-sulfonate) (ABTS), followed by syringaldazine. The Km value for ABTS was 2.12 mM with a Vmax value of 33.33 U/mg which was higher when compared with syringaldazine and guaiacol substrates. Sodium azide and EDTA inhibited the activity by 30%, whereas presence of Ca2+ and iron increased activity by 50%. The purified enzyme was immobilized in sodium alginate-silicon dioxide-polyvinyl alcohol beads and evaluated for diclofenac transformation studies. LC-MS analysis confirmed that immobilized laccase transformed diclofenac to 4-OH diclofenac after 4 h of incubation. 45 % of diclofenac was able to transform even at 3rd cycle of immobilized laccase use. Therefore, immobilized laccase can be used to transform or degrade several recalcitrant compounds from industrial effluents.

This study was aimed to understand the feasibility of banana and water hyacinth leaves and also applicable technology for xylitol along with the integrated production of bioethanol. The cellulosic fraction and hemicellulosic sugars from the individual agro-wastes were obtained separately by acid treatment. The hydrolysate obtained by enzymatic saccharification of cellulosic fraction of individual agro-waste were fermented to ethanol by Saccharomyces cerevisiae, whereas the detoxified hemicellulosic sugars to xylitol by un-adapted, adapted and immobilized cells of Candida tropicalis The maximum ethanol produced was 6.18 and 8.1 g L⁻¹ utilizing enzymatic hydrolysates of water hyacinth and banana leaves respectively. However, maximum xylitol was produced by immobilized cells of adapted Candida tropicalis utilizing detoxified acid hydrolysate of water hyacinth and banana leaves: 13.1 and 11.2 g L⁻¹ respectively, followed by the free cells. Hence utilization of these agro-wastes for the purpose allows the agricultural waste management and also finds applications in industries favoring co-production of xylitol and ethanol.

The original version of this article unfortunately contained a mistake in the equation under "Immobilized Laccase Activity and its Storage Stability" section.

This study was aimed to understand the feasibility of banana and water hyacinth leaves and also applicable technology for xylitol along with the integrated production of bioethanol. The cellulosic fraction and hemicellulosic sugars from the individual agro-wastes were obtained separately by acid treatment. The hydrolysate obtained by enzymatic saccharification of cellulosic fraction of individual agro-waste were fermented to ethanol by Saccharomyces cerevisiae, whereas the detoxified hemicellulosic sugars to xylitol by un-adapted, adapted and immobilized cells of Candida tropicalis The maximum ethanol produced was 6.18 and 8.1 g L−1 utilizing enzymatic hydrolysates of water hyacinth and banana leaves respectively. However, maximum xylitol was produced by immobilized cells of adapted Candida tropicalis utilizing detoxified acid hydrolysate of water hyacinth and banana leaves: 13.1 and 11.2 g L−1 respectively, followed by the free cells. Hence utilization of these agro-wastes for the purpose allows the agricultural waste management and also finds applications in industries favoring coproduction of xylitol and ethanol.

An extracellular laccase enzyme secreted from Sphingobacterium ksn-11 was purified to electrophoretic homogeneity, showing a molecular weight of 90 kDa. The purified enzyme was monomeric in nature confirmed by sodium dodecyl gel electrophoresis. The optimum temperature and pH were found to be 40°C and 4.5 respectively. The enzyme showed highest substrate specificity for 2,2 azino-bis (ethylthiozoline-6-sulfonate) (ABTS), followed by syringaldazine. The K m value for ABTS was 2.12 mM with a V max value of 33.33 U/mg which was higher when compared with syringaldazine and guaiacol substrates. Sodium azide and EDTA inhibited the activity by 30%, whereas presence of Ca 2+ and iron increased activity by 50%. The purified enzyme was immobilized in sodium alginate-silicon dioxide-polyvinyl alcohol beads and evaluated for diclofenac transformation studies. LC-MS analysis confirmed that immobilized laccase transformed diclofenac to 4-OH diclofenac after 4 h of incubation. 45 % of diclofenac was able to transform even at 3rd cycle of immobilized laccase use. Therefore, immobilized laccase can be used to transform or degrade several recalcitrant compounds from industrial effluents.