Simultaneous Loss of Proteinase- and Lactose-Utilizing Enzyme Activities in Streptococcus lactis and Reversal of Loss by Transduction1
AUTOR(ES)
McKay, L. L.
RESUMO
During studies on spontaneous loss of lactose metabolism in Streptococcus lactis C2, it was found that the lactose-negative (lac-) mutants were also proteinase negative (prt-). This pleiotropic effect was observed in S. diacetilactis 18-16, but not in S. cremoris B1. The lac-prt- mutants from S. lactis C2 were able to grow in milk, but no pH change or measurable protein breakdown occurred. When the milk was supplemented with glucose, a slow decline in pH occurred. Addition of a protein hydrolysate to milk did not stimulate acid production. When both supplements were added to milk, normal growth and pH change were obtained. When the lac-prt- mutant of S. lactis C2 was transduced with the temperate phage from the lac+prt+ parent culture, approximately equal numbers of lac+prt- and lac+prt+ transductants were obtained. When the spontaneous lac+prt- strain of S. lactis C2 was converted to a lac-prt- derivative and transduced, similar results were obtained. The co-transduction of the lactose and proteinase markers suggest they are closely associated. The findings indicate that the transducing phage from S. lactis C2 can be used to examine the causes of instability in both the lactose and proteinase enzyme systems of this organism.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=186722Documentos Relacionados
- Genetic Construction of Lactose-Utilizing Xanthomonas campestris
- Requirement for Phosphoglucomutase in Exopolysaccharide Biosynthesis in Glucose- and Lactose-Utilizing Streptococcus thermophilus
- Detection and characterization of lactose-utilizing Lactococcus spp. in natural ecosystems.
- Production of High-Viscosity Whey Broths by a Lactose-Utilizing Xanthomonas campestris Strain
- Construction of lactose-utilizing Xanthomonas campestris and production of xanthan gum from whey.