Alok Satlewal

Untreated wheat straw: potential source for diverse cellulolytic enzyme secretion by Penicillium janthinellum EMS-UV-8 mutant.

Study describes the production of cellulases by Penicillium janthinellum EMS-UV-8 using untreated wheat straw (WS), treated WS (acid, alkali, steam exploded, organo-solv) and pure cellulosic substrates (avicel, cellulose-II and carboxymethyl cellulose). Severely pretreated WS and cellulose-II produced more cellulolytic enzymes than untreated samples. XRD and FTIR analysis revels that the increase in the amorphous structure of pretreated WS/cellulose increases enzyme production. Enzyme samples prepared using different substrates were used for the hydrolysis of dilute acid treated wheat straw (DATWS), steam exploded wheat straw (SEWS) and avicel. The enzyme prepared using untreated WS gave more hydrolysis of DATWS and SEWS than the enzyme prepared using pretreated WS or pure cellulosic substrates. This revels that more diverse/potential enzymes were secreted by P. janthinellum EMS-UV-8 mutant using untreated WS. This study may contribute in production of efficient enzyme mixture/cocktail by single fungal strain for economic conversion of biomass to sugars.

Improved saccharification of pilot-scale acid pretreated wheat straw by exploiting the synergistic behavior of lignocellulose degrading enzymes

Requirement of high enzyme dosage for lignocellulosic biomass hydrolysis is one of the challenges for the viability of the second generation bioethanol technology. Here, an optimal enzyme mixture was developed by partially replacing the cellulase proportion with accessory enzymes (β-glucosidase, xylanase, pectinase, laccase) and its hydrolytic performance was compared with different commercial counterparts for the saccharification of pretreated wheat straw (PWS) using a 250 kg per day continuous pilot plant. Maximum degree of synergism was observed with xylanase followed by pectinase, laccase, and β-glucosidase. The statistically optimized enzyme mixture enhanced hydrolysis by 51.23% and 40.66% in 6 h and 24 h, respectively. This study elucidates that presence of even small amount of oligomers and cellobiose pose a strong inhibition for the enzymes. Therefore, development of an optimal enzyme formulation is a sustainable approach to reduce overall enzyme loading for biomass saccharification.

Investigating the enzyme-lignin binding with surfactants for improved saccharification of pilot scale pretreated wheat straw

In this study, commercial surfactants have been investigated at economically viable dosage to enhance the enzymatic saccharification of pretreated wheat straw at high solid loadings. Twenty one surfactants were evaluated with pilot scale pretreated wheat straw and mechanism of surfactant action has been elucidated. One surfactant has improved the saccharification of dilute acid wheat straw (DAWS) by 26.4% after 24h and 23.1% after 48h while, steam exploded wheat straw (SEWS) saccharification was increased by 51.2% after 24h and 36.4% after 48h at 10% solid loading. At 20% solid loading, about 31% increase in yield was obtained on DAWS and about 55% on SEWS after 48h. Further, lignin was isolated from pretreated wheat straws and characterized which revealed that SEWS derived lignin was more hydrophobic than DAWS lignin. This investigation suggests that surfactant supplementation during saccharification is an effective strategy to achieve higher saccharification yield.

Second generation bioethanol production at high gravity of pilot-scale pretreated wheat straw employing newly isolated thermotolerant yeast Kluyveromyces marxianus DBTIOC-35

Second-generation bioethanol production by a newly isolated thermotolerant yeast strain was studied at 42 °C and above using pilot-scale dilute acid pretreated wheat straw (WS) as feedstock. This strain was identified as Kluyveromyces marxianus DBTIOC-35 by biochemical characterization as well as molecular phylogenetic analysis of the ITS-5.8S rRNA gene and D1/D2 domain of the 26S rRNA gene after PCR amplification and sequencing. Simultaneous saccharification and fermentation (SSF) at 42 °C and 45 °C using 10% biomass loading resulted in ethanol titers of 29.0 and 16.1 g L−1, respectively. At 42 °C ethanol productivity was higher during SSF (0.92 g L−1 h−1) than separate hydrolysis and fermentation (SHF) (0.49 g L−1 h−1) at 20% biomass loading. The results indicated that at 20% biomass loading, SSF without pre-saccharification led to more ethanol production (66.2 g L−1 with 83.3% yield) at a faster rate than SSF with pre-saccharification (PSSF) which produced an ethanol titer of 61.8 g L−1, 77.7% yield and productivity of 0.86 g L−1 h−1. Based on these findings, application of newly isolated yeast K. marxianus DBTIOC-35 in SSF of lignocellulosic biomass can eliminate the pre-saccharification step which is a novel advantage of thermotolerant yeasts in terms of cutting down the overall biomass to bioethanol process time and enhancing bioethanol titer, yields and productivities.

Investigating Jatropha prunings as a feedstock for producing fermentable sugars and chemical treatment for process optimization

Jatropha curcas has been considered as a material of choice in India for the production of bio-diesel and a very large area has been planted in India. For better growth, Jatropha plants need extensive pruning once a year, and the pruning of a healthy two year old plant on an average gives about 4–6 kg of lignocellulosic material (LCM). Jatropha prunings can be available in significant amount on annual basis. These prunings have no other use and this material has potential to be an economical and suitable LCM for conversion to fermentable sugars, as these contain considerable amount of holocellulose. In this study, acid pretreatment of Jatropha pruning was carried out using dilute sulfuric acid. A wide range of variables, i.e., acid concentrations from 2.50% to 10.0%, temperature from 120 to 180 °C, and reaction time of 5–45 min were studied. Three response factors, namely, maximum xylose release, minimum inhibitors, and maximum enzymatic digestibility, were optimized by application Taguchi design. Pretrea...

Induction of cellulases by disaccharides or their derivatives in Penicillium janthinellum EMS-UV-8 mutant

ABSTRACT Disaccharides or their derivatives were analyzed for the induction of cellulases by Penicillium janthinellum EMS-UV-8 mutant. Among seven (Crocin, Gentiobiose, Cellobiose, α-D-Cellobiose octaacetate, Trehalose, Melibiose, Turanose) different compounds tested, α-D-Cellobiose octaacetate (COA) was found to be promising for induction of cellulases. The maximum of 0.8 IU/mL filter paper units, 4.7 IU/mL β–glucosidase and 1.0 mg/mL protein were produced using 0.1% (weight/volume) COA as an inducer and 1% glucose as a carbon source for growth. Next to COA the gentiobiose, trehalose, melibiose and turanose also induce cellulase but at a low level. The induction of cellulase was also analyzed in the presence and absence of light and it was found that the absence of light supports more growth and less cellulase induction, while in the presence of light mycelial growth was restricted but more cellulases were induced. The knowledge of cellulase induction by COA and light could be beneficial for large-scale cellulase production for conversion of cellulosic biomass to biofuels.

Indian Biofuel Progress, GHG Emission and GHG Savings by Biofuels: Comparative Assessment with World

Indian biofuel research and development is increasing day by day. Indian government made a plan to make 20% ethanol/biofuel blending by 2020. Few companies are already working on the biodiesel/lignocellulosic ethanol research and production, but they are not yet commercially working. The ethanol from molasses is available only for making 5% blending with gasoline, and appropriate policies are necessary to increase the ethanol production not only from one source but from other various renewable resources. Research institutions are working to make lignocellulosic biofuels available at lower price. The production and use of biofuel not only helps India at economic level but also may help to reduce some greenhouse gas emissions. At present, India is one of the most CO2-emitting countries but behind the USA and China. The recent report indicates the slowdown of global CO2 emission and that may be because of several reasons, but it is a good beginning.