CcpA Research Articles

A New Physiological Role for CcpA in Adaptation of Bacillus Subtilis to Sugar-Induced Osmotic Stress

The model Gram positive bacterium Bacillus subtilis is liable to be exposed to high salinity environments in its natural habitats and is often used in fermentation with high concentrations of glucose or other sugars High salinity or high concentrations of sugars can cause osmotic stress to B subtilis Past researches regarding osmoadaptation of B subtilis were mainly focused on responses to salt induced osmotic stress There was little or no mention about how B subtilis cells responded to sugar induced osmotic stress The catabolite control protein CcpA is known to be a global transcriptional regulator that mediates glucose repression of many catabolic genes and activation of genes involved in excretion of excess carbon in various Bacillus species However the physiological significance for CcpA mediated sugar activation of degU gltAB opuA opuE proHJ and the ilvB operon remained poorly defined Here based on the results from the literature search it is now proposed that CcpA mediated sugar activation of these osmoadaptive genes may facilitate the adaptation of B subtilis to sugar induced osmotic stress This finding could add a new physiological role to CcpA in B subtilis and probably its close relatives As to biotechnological application construction of B subtilis strains that could over express CcpA might potentially enhance their abilities to withstand higher concentrations of sugars for producing higher yields of various economically effective fermentation products

Relative significances of pH and substrate starch level to roles of Streptococcus bovis S1 in rumen acidosis.

To clarify the relative importance of pH and substrate starch level in fermentation characteristics and regulatory mechanism of Streptococcus bovis S1 in rumen acidosis, an in vitro fermentation of three levels of soluble starch (1, 3 and 9 g/L) was established with pH in the media were maintained constant at 5.5 or 6.5. The results showed that the dominant product of S. bovis S1 was lactate at both pH, the production depended on the starch level, and more lactate was produced at pH 6.5 than that at pH 5.5 (P < 0.001). At pH 5.5, the activity of lactate dehydrogenase (LDH) and α-amylase (α-AMY), their abundances, the relative expressions of LDH, PFL (gene encoding pyruvate formate-lyase), CCPA (gene encoding global catabolite control protein A) and α-AMY genes were higher than those at pH 6.5 (P < 0.05), whereas the concentration of fructose-1,6-diphosphate (FDP) was lower. The activity of LDH, α-AMY and FDP, and the relative expressions of LDH, PFL, CCPA and α-AMY genes were, in general, positively related to the starch level. The canonical regression analysis indicated that the pH had more profound effect compared with the starch level, in terms of the acid productions, enzyme activity and gene expressions. It was concluded that the fermentation of S. bovis was regulated at the transcription level in response to both pH and substrate starch concentration, but more sensitive to pH changes.

Contributions of XylR, CcpA and

Contributions of XylR, CcpA and