Expression of virulence genes in Bacillus cereus depending on various carbohydrates
|Background: Bacillus cereus can cause two types of food poisoning, the rapid emetic and late diarrheal syndromes, and a variety of infections. Previous studies have indicated that the enterotoxin productions by this Gram-positive bacterium are highly influenced by carbohydrates. The aim of our study was to compare transcriptomes of B. cereus growing on various carbohydrates and our interest further focused on virulence genes. Methods: Gene expression was monitored by Illumina sequencing technology after a 12-hour growth of B. cereus (strain ATCC 14579) on fructose, glucose, galactose, sucrose, lactose, or xylitol, and compared to control culture without carbohydrates. Results were considered as significant at Q-value <0.01. Results: The nheB (non-haemolytic enterotoxin B) and sph (sphingomyelinase) were both significantly downregulated in the presence of glucose, while an elevated transcript level of sph during bacterial growth on galactose was found. The significant increase in transcript level of a virulence factor plC (phospholipase C) in the presence of galactose, lactose, or xylitol was observed. Although tlyA (haemolysin A) was significantly upregulated when bacteria grew on fructose or sucrose, hlyIII (haemolysin III) expression was downregulated in the presence of sucrose. Conclusions: Gene expression profiling has expanded more in detail the correlation between toxin production and various carbohydrates. Preliminary data may contribute designing a suitable diet used in the treatment of these gastrointestinal illnesses.