Several local acrylamide-degrading bacteria have been isolated. One of the isolate that exhibited the highest growth on acrylamide as a nitrogen source was then further characterized. The isolate was tentatively identified as Bacillus cereus strain DRY135 based on carbon utilization profiles using Biolog GP plates and partial 16S rDNA molecular phylogeny. The isolate grew optimally in between the temperatures of 25 and 30 degrees C and within the pH range of 6.8 to 7.0. Glucose, fructose, lactose, maltose, mannitol, citric acid and sucrose supported growth with glucose being the best carbon source. Different concentrations of acrylamide ranging from 100 to 4000 mg l(-1) incorporated into the growth media shows that the highest growth was obtained at acrylamide concentrations of between 500 to 1500 mg l(-1). At 1000 mg l(-1) of acrylamide, degradation was 90% completed after ten days of incubation with concomitant cell growth. The metabolite acrylic acid was detected in the media during degradation. Other amides such as methacrylamide, nicotinamide, acetamide, propionamide and urea supported growth with the highest growth supported by acetamide, propionamide and urea. Strain DRY135, however was not able to assimilate 2-chloroacetamide. The characteristics of this isolate suggest that it would be useful in the bioremediation of acrylamide.
Enterotoxigenic Bacillus cereus was detected in cooked foods (17), rice noodles (3), wet wheat noodles (2), dry wheat noodles (10), spices (8), grains (4), legumes (11) and legume products (3). One hundred ninety-four (42.3%), 70 (15.3%) and 23 (5.2%) of the 459 presumptive B. cereus colonies isolated from PEMBA agar were identified as B. cereus, Bacillus thuringiensis and B. mycoides, respectively. B. cereus isolates were examined for growth temperature, pH profile and enterotoxin production using both TECRA-VIA and BCET-RPLA kits. One hundred seventy-eight (91.8%) and 164 (84%) of the strains were enterotoxigenic as determined using TECRA-VIA and BCET-RPLA, respectively. Eighty-two (50%) of the enterotoxigenic strains were capable of growing at 5 degrees C, and 142 (86.6%) grew at 7 degrees C within 7 days of incubation. The enterotoxigenic strains did not grow at pH 4.0 but 69 (42.0%) of the strains were able to grow at pH 4.5 within 7 days at 37 degrees C. The isolates were resistant to ampicillin (98.8%), cloxallin (100%) and tetracycline (61.0%), and susceptible to chloroamphenicol (87%), erythromycin (77.4%), gentamycin (100%) and streptomycin (98.7%).
Bacillus cereus endocarditis is rare. It has been implicated in immunocompromised individuals, especially in intravenous drug users as well as in those with a cardiac prosthesis. The patient was a 31-year-old ex-intravenous drug addict with a past history of staphylococcal pulmonary valve endocarditis, who presented with symptoms of decompensated cardiac failure. Echocardiography showed severe aortic regurgitation with an oscillating vegetation seen on the right coronary cusp of the aortic valve. The blood cultures grew Bacillus cereus. We report this as a rare case of Bacillus cereus endocarditis affecting a native aortic valve.
A bacterial strain, KM1S, was isolated from a Malaysian rainforest soil sample by using a defined enrichment medium that specifically facilitates selection of quorum quenching bacteria. KM1S was clustered closely to Bacillus cereus by 16S ribosomal DNA sequence analysis. It degraded N-3-oxo-hexanoyl homoserine lactone and N-3-oxo-octanoyl homoserine lactone in vitro rapidly at 4.98 and 6.56 microg AHL h(-1) per 10(9) CFU/ml, respectively, as determined by the Rapid Resolution Liquid Chromatography. The aiiA homologue, encoding an autoinducer inactivation enzyme catalyzing the degradation of N-acylhomoserine lactones, of KM1S was amplified and cloned. Sequence analysis indicated the presence of the motif (106)HXDH-59 amino acids-H(169)-21 amino acids-D(191) for N-acylhomoserine lactone lactonases.