NEW YEAST STRAINS FOR ALCOHOLIC FERMENTATION AT HIGHER SUGAR CONCENTRATION

New yeast strains for alcoholic fermentation were isolated from samples collected from Brazilian alcohol factories at the end of the sugar cane crop season. They were selected by their capacity of fermenting concentrated sugar cane syrup as well as high sucrose concentrations in synthetic medium with a conversion efficiency of 89-92%. The strains were identified as Saccharomyces cerevisiae.

ENTEROTOXIN PRODUCTION IN STRAINS OF CAMPYLOBACTER-JEJUNI, ISOLATED FROM SWINE DIARRHEA

One hundred and twenty-six strains of Campylobacter jejuni isolated from swine with diarrhea were examined for the production of enteroxin, by culture filtrate inoculation into ileal loops in several animal species.Four (3,1 %) of the strains tested produced fluid in ligated ileal loop of albino rabbit, 19 (15 %) in rat and 14(11, 1 %) in swine. By the test of intragastric inoculation in suckling mouse, none of the strains revealed capacity to produce enterotoxin, although two strains were considered suspicious. Twelve (54,5 %) of the strains that induced ileal fluid in rat and swine produced cytotoxic effect in monkey kidney cells (Vero), affecting up to 60 % of the monolayer. However, no alteration was observed in hamster kidney cells (BHK).

Evaluation of fitness components in strains of Drosophila mulleri carrying different genotypes for an esterase

Several fitness components in strains of Drosophila mulleri carrying the slow or the fast alleles for the major beta esterase (esterase-4) found in this species, as well as in heterozygous flies in which the slow or fast alleles came from one of the parents, were evaluated. Twelve components were analysed including longevity of both virgins and mated males and females, productivity, viability, including the egg-larva, egg-pupa, egg-imago and pupa-imago periods. These parameters were used to estimate the total fitness for each genotype. The best score was reached by individuals having the Est-4(S)/Est-4(S) genotype (scored at 1.000), followed by a fitness value of 0.892 presented by the Est-4(F)/Est-4(S) genotype (with the fast allele from maternal origin), 0.863 for the Est-4(F)/Est-4(F) and 0.842 for the Est-4(S)/Est-4(F) genotypes (with Est-4(F) maternal origin). These results suggested a higher relative adaptability of the Est-4(S)/Est-4(S) genotype followed by the Est-4(F)/Est-4(S) hybrid that possessed the allele Est-4(S) of maternal origin, which was incompatible with predictions of neutral polymorphism.

Esterase patterns and phylogenetic relationships of species and strains included in the Drosophila buzzatii cluster

Ten strains of two species in the Drosophila buzzatii cluster (D. serido and D. seriema) were examined as to esterase patterns using polyacrylamide gel electrophoresis. The migration rate of esterases, and their substrate specificity to alpha and beta naphthyl acetates, were analysed. Other esterase features such as inhibition behaviour, presence in males and females and location in the head, thorax or abdomen of flies, were also examined. The present data,together with results obtained by others for eight strains of D. koepferae, D. serido, D. seriema and D. buzzatii, show that 69 bands have been detected in the eighteen strains studied. This total number of bands was used for comparison of strains and species by similarity index, analysis of dependence and cluster analysis. The comparisons confirmed the existence of a high degree of similarity among D. seriema strains and among D. koepferae strains, but indicated differentiation among the D. serido strains. Two strains (D69R2 and D69R5) which differed from the others of the latter species, showed closer affinities with D. buzzatii, which indicates the need for further work on those strains classified as D. serido.