Extracellular enzyme production and enterotoxigenic gene profiles of Bacillus cereus and Bacillus thuringiensis strains isolated from cheese in Turkey

Abstract

a b s t r a c tThe aim of the present study was to investigate the biochemical characteristics, extracellular enzyme production and enterotoxigenic genes contents of 6 Bacillus cereus and 22 Bacillus thuringiensis strains, isolated from 100 cheese samples in Turkey. Crystal morphologies of B. thuringiensis strains were found either spherical (n = 12) or spherical and irregular-shaped (n = 10) by phase contrast microscopy. B. cereus and B. thuringiensis strains were found to produce extracellular enzymes, respectively: gelatinase (83% and 91%), DNase (83% and 77%), lecithinase (83% and 95%), protease on skim milk agar (100% and 100%), protease on milk agar (100% and 91%), protease on casein agar (83% and 77%), xylanase (100% and 45%), and cellulase (0% and 41%), and amylase (83% and 27%). All of the strains, except for Bt-D1, hydrolyzed Tween 20 (96%), but not Tween 80 or tributyrin. Pectinolytic activity was obtained to be the least frequent (4%). PCR analysis showed that all strains contained nheA, nheB, nheC and hblD genes. The hblA and hblC genes were present in 2 and 4 of B. thuringiensis strains, respectively. The bceT gene was detected in 1 B. cereus and 9 B. thuringiensis strains. The entFM gene was detected more frequently in B. thuringiensis (82%) than in B. cereus strains (50%). To our knowledge, this is the first report about the isolation and identification of enterotoxigenic B. cereus and B. thuringiensis strains from cheese samples in Turkey.

Determination of Enterotoxigenic Gene Profiles of Bacillus cereus Strains Isolated from Dairy Desserts by Multiplex PCR

“…cereus contamination has been determined previously by Ozdemir [30] , in pasteurised milk samples and was isolated from 56 (46.6%) of the samples. Molva et al [31] , also detected B. cereus from 6% of cheese samples.…”

“…In the detection of enterotoxin genes, 30% of B. cereus strains were found to carry the three hbl genes. Molva et al [31] , found that all detected strains contained hblD gene. Hansen and Hendriksen [33] , reported that 64% of B. cereus strains contained this gene.…”

“…Nduhiu et al [36] , detected 3.9% nheA, 19.6% nheB and 3.9% nheC genes from milk and 3.9% nheA, 11.8% nheB and 3.9% nheC genes from cheese from their B. cereus strains. However, several authors have also reported that almost all B. cereus strains contain nhe genes [31,33,37,38] .…”

Enhanced Endoglucanase Production by Bacillus aerius on Mixed Lignocellulosic Substrates

“…The extracellular production of enzymes among Bacillus spp. is common (Priest 1977;Molva et al 2009). Some endoglucanase activity was also detected as intracellular and membrane-bound when B. aerius S5.2 was grown on both substrates; however, this expression was minimal compared with extracellular production.…”

Characterization of Bacillus cereus spores isolated from Algerian processed cheese

“…In Algeria B. cereus is not researched as poisoning causal bacterium due to dairy products. So far, few or rare works have reported B. cereus and its toxins in processed cheese while some works have studied this bacterium on cheddar cheese, raw material used for manufacturing of processed cheese (Molva et al, 2009;Cherif-Antar et al, 2015 (Upasana and Labbé, 2016).…”