Aims: The present investigation deals with the development of thermotolerant mutant strain of yeast for studying enhanced productivity of ethanol from molasses in a fully controlled bioreactor. Methods and Results: The parental culture of Saccharomyces cerevisiae ATCC 26602 was mutated using UV treatment. A single thermotolerant mutant was isolated after extensive screening and optimization, and grown on molasses medium in liquid cultures. The mutant was 1AE45-fold improved than its wild parent with respect to ethanol productivity (7AE2 g l )1 h )1 ), product yield (0AE44 g ethanol g )1 substrate utilized) and specific ethanol yield (19AE0 g ethanol g )1 cells). The improved ethanol productivity was directly correlated with titres of intracellular and extracellular invertase activities. The mutant supported higher volumetric and product yield of ethanol, significantly (P £ 0AE05) higher than the parental and other strains. The mutated cultures produced 1AE8-and 2AE6-fold more extracellular and intracellular invertase productivity, respectively, than that produced by its wild parent at 40°C. Thermodynamic studies revealed that the cell system exerted protection against thermal inactivation during formation of products. Conclusions: A mutant derivative of Sacchromyces cerevisiae with improved productivity of ethanol and invertases has been obtained, which showed concomitant improvement in thermostability of endogenous metabolism for formation of both ethanol and invertases. Significance and Impact of the Study: The results of the present study are of commercial value as the mutant can be used for ethanol production in parts of Pakistan where the temperature may go up to 40°C in April. Ethanol product yield coefficient and volumetric productivity, revealed the hyper-productivity of ethanol from molasses at 40°C, which is not appropriate for wild organism.

Demethylation of softwood kraft lignin from woody biomass to improve the hydroxyl number in modified demethylated lignin and to produce lignin-based polyols was investigated using several biophysical techniques. Lignin is a tremendously underdeveloped natural polymer co-generated through papermaking and biomass fractionation. Molecular weights of lignins were analyzed by high-performance size-exclusion chromatography (HPSEC). Molecular weights of softwood kraft lignin (SKL) and demethylated lignin (DL) were determined as 1071 and 891 gmol-1 , respectively. For demethylation, iodocyclohexane in dimethyl formamide (DMF) was used under reflux conditions, with a resulting yield of 87%. Fourier transform infrared spectroscopy (FTIR) was used to determine characteristic absorption peaks of softwood kraft lignin and demethylated lignin. Significant spectral differences were noticed between the two types of lignin due to changes in chemical structure. Total hydroxyl numbers were determined by titration. Phosphorus nuclear magnetic resonance spectrometry (31 P-NMR) was employed to analyze the structure of lignin and different types of phenolic hydroxyl units. Nevertheless, further chemical and biological modifications within the lignin molecule are needed for various industrial applications to synthesize polyurethane foam by using chemically modified lignin-based polyols.

Fungal species for ligninases production was investigated by 18S ribosomal DNA sequence analysis. Two primer sets were chosen to amplify a major part of the 18S rDNA, which resulted in intense PCR product of approximately 550-820 bp in size per sample. The results suggest that the 18S rDNA-based approach is a useful tool for identification of unknown potential fungal species for ligninases production. The isolated fungal species produces mainly manganese peroxidase (MnP). The enzyme oxidized a variety of the usual MnP substrates, including lignin related polyphenols. Time course studies showed that maximum production of ligninolytic enzymes MnP (64 IU L⁻¹), lignin peroxidase (26.35 IU L⁻¹), and laccase (5.44 IU L⁻¹), respectively, were achieved after 10 days of cultivation under optimum conditions. Furthermore, the biological decolorization of Remazol Brilliant Blue R dye following 10 days of cultivation was 94 %. NCBI BLAST was used to search for closest matched sequences in the GenBank database and based on sequence homology the first BLAST hit was Dothioraceae sp. LM572 with accession number EF060858.1.

This paper describes the comparison of enzymatic, alkaline, and UV/H 2 O 2 treatments for the extraction of beetleinfested lodgepole pine (BILP) and mixed aspen barks polyphenolic extractives. The concept of green polymers has become more appealing due to the presence of large volumes of processing residuals from the timber and pulp industries. This, in turn, supports the idea of developing new polymers based on bark extractives. Here, we used a chromatographic method to determine the chemical composition of some of the polyphenolic compounds in bark extractives and observed the effect of different extraction methods on extraction yield. Polyphenolic compounds separation was performed using HPLC in reverse-phase mode with an octadecylsilane (ODS), C18 column (3 μm particle size), and an UV detector. Detection wavelengths of 280, 310, and 370 nm were selected to allow better separation of each compound. The comparative studies and effects of enzymatic, alkaline, and UV/H 2 O 2 treatments on extractives yield and component contents were investigated. UV/H 2 O 2 treatment exhibited the highest yield with 54% of dry bark weight extracted and was found to degrade larger amounts of lignins/tannins than enzymatic and alkaline treatments. Conversely, enzymatic treatment was good for holocellulose.