Growth on lactose by strains of Streptococcus mutans resulted in the induction of the lactose-phosphoenolpyruvate-phosphotransferase system, phospho-beta-galactosidase, and the enzymes of the tagatose 6-phosphate pathway.

The initial step of disaccharide dissimilation by Actinomyces viscosus serotype 2 strain M-100 was studied. Sucrase activity was found in the 3,000 X g particulate fraction and the 37,000 X g soluble fraction of the cells, whereas lactase activity was found almost exclusively in the 37,000 X g soluble fraction. Neither sucrase nor lactase activity was appreciable in the culture liquor. Sucrose ...

1. The previous study (Conchie, Gelman & Levvy, 1967b) of the specificity of beta-glucosidase, beta-galactosidase and beta-d-fucosidase in barley, limpet, almond emulsin and rat epididymis was extended to alpha-l-arabinosidase. 2. The inhibitory action of l-arabinono-(1-->5)-lactone was tested against all four types of enzyme, and alpha-l-arabinosidase was examined for inhibition by glucono-, g...

BACKGROUND The yields of soluble recombinant proteins expressed in bacteria are often low due to the tendency of the heterologous proteins to form aggregates. Therefore, aggregation reporters have been envisaged to simplify the comparison among different expression conditions and to speed up the identification of suitable protocols that improve the solubility. The probe we used is composed by a...

Bacteriophage ch2, a virulent bacteriophage of Lactobacillus bulgaricus CH2, was characterized according to its morphology, genome size, structural proteins, and growth kinetics. Electron micrographs revealed that bacteriophage ch2 has an icosahedral head of 50-nm diameter and a long tail of 170 nm. Its genome is linear and 35 kilobases in length, and its structural proteins consist of two majo...

Escherichia coli has two enzymes catalyzing the synthesis of guanosine tetraphosphate (ppGpp), designated ppGpp synthetase I (PSI = RelA) and II (PSII), whose activities are regulated differently. Until now, the gene for PSII had not been identified. Here, an E. coli relA1 strain that expresses lacZ from an rrnB P1 promoter was used to screen mutants with increased beta-galactosidase activity o...