The culture-medium composition was optimised, on a shake-flask scale, for simultaneous production of high activities of endoglucanase and beta-glucosidase by Thermoascus aurantiacus using statistical factorial designs. The optimised medium containing 40.2 g l(-1) Solka Floc as the carbon source and 9 g l(-1) soymeal as the organic nitrogen source yielded 1130 nkat ml(-1) endoglucanase and 116 nkat ml(-1) beta-glucosidase activities after 264 h as shake cultures. In addition, good levels of beta-xylanase (3479 nkat ml(-1)) and low levels of filter-paper cellulase, beta-xylosidase, alpha-L-arabinofuranosidase, beta-mannanase, beta-mannosidase, alpha-galactosidase and beta-galactosidase were detected. Batch fermentation in a 5-1 laboratory fermentor using the optimised medium allowed the production of 940 nkat ml(-1) endoglucanase and 102 nkat ml(-1) beta-glucosidase in 192 h. Endoglucanase and beta-glucosidase showed optimum activity at pH 4.5 and pH 5, respectively, and they displayed optimum activity at 75 degrees C. Endoglucanase and beta-glucosidase showed good stability at pH values 4-8 and 4-7, respectively, after a prolonged incubation (48 h at 50 degrees C). Endoglucanase had half-lives of 98 h at 70 degrees C and 4.1 h at 75 degrees C, while beta-glucosidase had half-lives of 23.5 h at 70 degrees C and 1.7 h at 75 degrees C. Alkali-treated bagasse, steam-treated wheat straw, Solka floc and Sigmacell 50 were 66, 48.5, 33.5 and 14.4% hydrolysed by a crude enzyme complex of T. aurantiacus in 50 h.

Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in the developing world (45). Escherichia coli, a gram-negative bacillus, is among the normal microbial flora that exists in the healthy human intestine (11). However, some of the E. coli serotypes cause diarrhea or food poisoning, mostly in infants and children. Following the recognition of certain pathotypes of E. coli as human diarrheagenic pathogens and the establishment of a serotyping system, serovars associated with diarrheal diseases have gained increasing interest (47). At coli strains revealed 47%, 30%, and 6% to belong to EPEC, ETEC, and EHEC pathotypes, respectively. The majority of the 160 strains tested were resistant to commonly used antimicrobial agents. Plasmid profiling showed a total of 17 different bands ranging from 1.3 to 40 kb. However, 35% of the strains did not contain any detectable plasmid, implying no correlation between plasmid and drug resistance. Although virulence gene profiling revealed 97 (61%) of the strains to harbor the gene encoding heat-stable enterotoxin (ST), 2 for the gene encoding Shiga toxin (Stx), and none for the gene for heat-labile enterotoxin (LT), serotype-based pathotyping of E. coli was not fully supported by this gene profiling. A dendrogram derived from the PFGE patterns of 22 strains of three predominant serogroups indicated two major clusters, one containing mainly serogroup O55 and the other O8. Three strains of identical PFGE profiles belonging to serogroup O55 were isolated from three distinct areas, which may be of epidemiological significance. Finally, it may be concluded that serotype-based pathotyping may be useful for E. coli strains of clinical origin; however, it is not precise enough for reliably identifying environmental strains as diarrheagenic. Phenotypic and Molecular Characteristics of

Sugar cane bagasse is a cheap lignocelluloses which has high carbohydrate content and, if properly pre-treated, could be converted to fermentable sugar. In this study various fungal isolates isolated from lignocellulosic waste were assayed for their CMCase, FPase and xylanase activity. Four potent plant cell wall-degrading fungi were identified as Trichoderma sp., Aspergillus niger, Cladosporium sp. and Curvularia sp. Among these isolates Trichoderma sp. produced the highest enzymatic activity in the culture filtrates containing steamed NaOH treated-bagasse. The yield of endo-β-glucanase i.e., carboxymethylcellulase (CMCase), FPase and xylanase were 0.977, 0.110 and 9.280 U/ml. The highest degree of saccharification (D o S) was also achieved by Trichoderma sp. which was 45.71%. Trichoderma sp. is a potential source of extracellular hydrolases, which can be used for enzymatic saccharification of bagasse to produce fermentable sugar for ethanol production.

No abstract

No abstract