Prospects of thermotolerant Kluyveromyces marxianus for high solids ethanol fermentation of lignocellulosic biomass.

Simultaneous saccharification and fermentation (SSF) is effective for minimizing sugar inhibition during high solids fermentation of biomass solids to ethanol. However, fungal enzymes used during SSF are optimal between 50 and 60 °C, whereas most fermentative yeast, such as Saccharomyces cerevisiae, do not tolerate temperatures above 37 °C. Kluyveromyces marxianus variant CBS 6556 is a thermotolerant eukaryote that thrives at 43 °C, thus potentially serving as a promising new host for SSF operation in biorefineries. Here, we attempt to leverage the thermotolerance of the strain to demonstrate the application of CBS 6556 in a high solids (up to 20 wt% insoluble solid loading) SSF configuration to understand its capabilities and limitations as compared to a proven SSF strain, S. cerevisiae D5A. For this study, we first pretreated hardwood poplar chips using Co-Solvent Enhanced Lignocellulosic Fractionation (CELF) to remove lignin and hemicellulose and to produce cellulose-enriched pretreated solids for SSF. Our results demonstrate that although CBS 6556 could not directly outperform D5A, it demonstrated similar tolerance to high gravity sugar solutions, superior growth rates at higher temperatures and higher early stage ethanol productivity. We discovered that CBS 6556's membrane was particularly sensitive to higher ethanol concentrations causing it to suffer earlier fermentation arrest than D5A. Cross-examination of metabolite data between CBS 6556 and D5A and cell surface imaging suggests that the combined stresses of high ethanol concentrations and temperature to CBS 6556's cell membrane was a primary factor limiting its ethanol productivity. Hence, we believe K. marxianus to be an excellent host for future genetic engineering efforts to improve membrane robustness especially at high temperatures in order to achieve higher ethanol productivity and titers, serving as a viable alternative to D5A.

Genetic variation and haplotype structures of innate immunity genes in eastern India.

This study reports results of an extensive and comprehensive study of genetic diversity in 12 genes of the innate immune system in a population of eastern India. Genomic variation was assayed in 171 individuals by resequencing approximately 75kb of DNA comprising these genes in each individual. Almost half of the 548 DNA variants discovered was novel. DNA sequence comparisons with human and chimpanzee reference sequences revealed evolutionary features indicative of natural selection operating among individuals, who are residents of an area with a high load of microbial and other pathogens. Significant differences in allele and haplotype frequencies of the study population were observed with the HapMap populations. Gene and haplotype diversities were observed to be high. The genetic positioning of the study population among the HapMap populations based on data of the innate immunity genes substantially differed from what has been observed for Indian populations based on data of other genes. The reported range of variation in SNP density in the human genome is one SNP per 1.19kb (chromosome 22) to one SNP per 2.18kb (chromosome 19). The SNP density in innate immunity genes observed in this study (>3SNPskb(-1)) exceeds the highest density observed for any autosomal chromosome in the human genome. The extensive genomic variation and the distinct haplotype structure of innate immunity genes observed among individuals have possibly resulted from the impact of natural selection.

Gender differences in healthcare-seeking during common illnesses in a rural community of West Bengal, India.

This follow-up observational study examined gender disparities in seeking healthcare and in home management of diarrhoea, acute respiratory infections, and fever among 530 children (263 boys and 267 girls) aged less than five years in a rural community of West Bengal, India, from June 1998 to May 1999. Of 790 episodes detected by a weekly surveillance, 380 occurred among boys and 410 among girls. At the household level, girls were less likely to get home fluids and oral rehydration solutions (ORS) during diarrhoea. Qualified health professionals were consulted more often (p = 0.0094) and sooner for boys than for girls (8.3 +/- 4.5 hours vs 21.2 +/- 9.5 hours), for which parents also travelled longer distances (3.3 km for boys vs 1.6 km for girls). Expenditure per treated episode (Rs 76.76 +/- 69.23 in boys and Rs 44.73 +/- 67.60 in girls) differed significantly (p = 0.023). Results of logistic regression analysis showed that chance of spending more money was 4.2 [confidence interval (CI) 1.6-10.9] times higher for boys. The boys were 4.9 (CI 1.8-11.9) times more likely to be taken early for medical care and 2.6 (CI 1.2-6.5) times more likely to be seen by qualified allopathic doctors compared to girls. Persistence of gender disparities calls for effective interventions for correction.