Chandrakant Ankolekar

Detection of toxigenic Bacillus cereus and Bacillus thuringiensis spores in U.S. rice.

Bacillus cereus is a gram-positive, endospore forming pathogenic bacterium that is ubiquitous in the environment and is frequently associated with emetic and diarrheal types of foodborne illness. In this study, 178 samples of raw rice from retail food stores were analyzed for the presence of B. cereus spores. Spores of Bacillus species were found in 94 (52.8%) of the rice samples with an average concentration of 32.6 CFU/g (3.6-460 CFU/g for B. cereus and 3.6-23 CFU/g for Bacillus thuringiensis). Eighty three of the 94 isolates were identified as B. cereus and 11 were identified as B. thuringiensis. Bacillus mycoides (240 CFU/g) was the predominant isolate in one rice sample. Using PCR the isolates were checked for the presence of the cereulide synthetase gene (ces), the hblA and hblD genes of the hemolysin BL (HBL) complex and the nheA and nheB genes of the nonhemolytic (NHE) enterotoxin complex. The ces gene was not identified in any of the isolates. By contrast 47 (56.6%) B. cereus isolates possessed the hblA and hblD genes and 74 (89.1%) isolates possessed the nheA and nheB genes. As determined by commercial assay kits, forty four (53.0%) of the 83 B. cereus isolates produced both NHE and HBL enterotoxins whereas 78 (93.9%) were positive for either one or the other. Protein toxin crystals were detected visually in the 11 B. thuringiensis isolates. PCR analysis revealed 10 (90.9%) of those 11 isolates carried the cry gene. All the B. thuringiensis isolates were positive for NHE and HBL enterotoxins. Our results suggest that foodborne illness in the U.S. due to B. cereus with rice as the vehicle would be most likely associated with the diarrheal-type syndrome.

Inhibitory potential of tea polyphenolics and influence of extraction time against Helicobacter pylori and lack of inhibition of beneficial lactic acid bacteria.

Tea polyphenolics such as catechins are known to have the potential to inhibit many bacterial pathogens. Helicobacter pylori has been identified as an etiologic agent in the development of gastric ulcer, peptic ulcer, gastritis, and many other stomach-related diseases. In this study, we investigated the effect of 9 tea extracts--3 different brands representing 4 different processed types (white, green, oolong, and black)--on the inhibition of H. pylori. Extraction times of 2 and 5 minutes were compared. Most 5-minute extracts showed H. pylori inhibition, whereas 2-minute extracts only of Choice darjeeling black and Tazo white showed inhibition. No recovery was observed after the addition of 0.5 and 5 mM proline, indicating that tea polyphenols do not inhibit H. pylori by inhibition of proline oxidation via proline dehydrogenase. Extracts that showed inhibition were further evaluated for their effect on beneficial lactic acid bacteria. None of the samples showed inhibition, suggesting that tea might be able to inhibit H. pylori without affecting the beneficial lactic acid bacteria. High-performance liquid chromatography indicated the presence of gallic acid, quercetin, caffeine, and tea catechins (including catechin, epicatechin, and epigallocatechin) in all the tea samples. Our study indicates that tea can be potentially used as a low-cost dietary support to combat H. pylori-linked gastric diseases without affecting the beneficial intestinal bacteria.

Physical Characteristics of Spores of Food-Associated Isolates of the Bacillus cereus Group

ABSTRACT All 47 food-borne isolates of Bacillus cereus sensu stricto, as well as 10 of 12 food-borne, enterotoxigenic isolates of Bacillus thuringiensis, possessed appendages. Spores were moderately to highly hydrophobic, and each had a net negative charge. These characteristics indicate that spores of food-associated B. thuringiensis and not only B. cereus sensu stricto have high potential to adhere to inert surfaces.

Varietal influences on antihyperglycemia properties of freshly harvested apples using in vitro assay models.

The well-known health benefits of apples have been attributed in part to the presence of polyphenols and related antioxidant capacity. The consumption of apples could provide health benefits by reducing the risk for chronic diseases such as metabolic syndrome disease, including type 2 diabetes. Thus, the objective of this study was to investigate the phenolic-linked antihyperglycemia bioactive factors in aqueous and 12% ethanol extracts of peel and pulp from 10 different freshly harvested apple varieties commonly consumed in the United States. The extracts were analyzed for total soluble phenolics, 2,2-diphenyl-1-picrylhydrazyl-linked antioxidant activity, and their associated in vitro α-glucosidase and α-amylase inhibitory activities. In general, peel extracts had higher total soluble phenolic content and related antioxidant capacity than pulp extracts. Quercetin derivatives, protocatechuic acid, chlorogenic acid, and p-coumaric acid were detected, and the amount varied significantly between aqueous and ethanolic extracts. Honeycrisp and Red Delicious varieties had the highest total phenolic contents and a significant correlation with antioxidant capacity (r = 0.91). In addition, high α-amylase and α-glucosidase inhibitory activities in aqueous pulp extracts were found. However, the peel extracts had the highest α-glucosidase inhibitory activity along with low α-amylase inhibitory activity. No correlation between α-amylase inhibitory activity and total phenolic content was observed. However, positive correlations between α-glucosidase inhibitory activity and total phenolics in aqueous (r = 0.50) and ethanolic (r = 0.70) extracts were observed. This study provides the biochemical rationale for animal and clinical studies to determine the suitable varieties with optimum bioactive factors with antihyperglycemia potential.

Anti-Hyperglycemia Properties of Tea (Camellia sinensis) Bioactives Using In Vitro Assay Models and Influence of Extraction Time

Tea (Camellia sinensis) has well-known health benefits, which are attributed to its polyphenolic metabolites. This research explored the potential of regular tea consumption and influence of extraction time typically used in daily consumption of tea, as a therapeutic dietary support for potential management of early stage type 2 diabetes using in vitro assay models. Extraction times of 2 and 5 minutes were compared. The 5-minute extraction time had significantly higher total phenolic content compared with the 2-minute extraction time. Choice Darjeeling 5-minute extraction yielded the highest amount of total phenolics (299.6 ± 5.9 mg/g), followed by Tazo Black 5-minute extraction (240 ± 9.7 mg/g), whereas Bigelow Green 2-minute extraction had the lowest total phenolic content (53 ± 8.2 mg/g). 1,1-Diphenyl-2-picrylhydrazyl scavenging-linked antioxidant activity was high (81-91%) for all types evaluated, and for most samples it was influenced by the extraction time. Similarly, high in vitro α-glucosidase inhibition was observed in almost all the samples assayed, and for most samples the 5-minute extraction had significantly higher inhibition compared with the 2-minute extraction time. The most fermented teas showed highest α-amylase inhibition: Choice Darjeeling 5-minute extraction had the highest inhibition (84.1%), followed by Tazo Black 5-minute extraction (71.6%). Angiotensin converting enzyme inhibition was not observed in any sample. Overall, the 5-minute extraction time was found to have more relevance for potential benefits for managing hyperglycemia than the 2-minute procedure. This research suggests that tea offers an attractive potential strategy to regulate postprandial hyperglycemia toward an overall dietary support for type 2 diabetes management.

Survival during cooking and growth from spores of diarrheal and emetic types of Bacillus cereus in rice

Bacillus cereus is a gram-positive, spore-forming, facultative anaerobe that is responsible for two types of gastrointestinal diseases: emesis and diarrhea. A significant difference in the D(95 degrees C)-values of spores of the emetic and the diarrheal types was initially determined. A mixture of B. cereus spores of the diarrheal type was inoculated into cooked rice. At inoculation levels of 2.5 x 10(2) spores per g of rice, cell numbers of 6.64 log were detected after 22 h at 20 degrees C and 6.81 log after 34 h at 17 degrees C, whereas at 12 degrees C the counts did not go above 4.0 log even after 48 h. When added to raw rice before cooking at inoculum levels of 10(3)/g, the number of viable spores decreased by 2 log, and a <1-log increase in cell numbers occurred after holding at 20 degrees C for 24 h. In contrast, the emetic spores survived and increased approximately 20-fold. Nonhemolytic enterotoxin was not detected in cooked rice at cell numbers of 8.0 log. Results here provide evidence that the absence of foodborne illness caused by the B. cereus diarrheal biotype with rice as the vehicle is due to the inability of their spores to survive and grow following standard heat processing procedures.

Phenolic Bioactive Modulation by Lactobacillus acidophilus Mediated Fermentation of Cherry Extracts for Anti-Diabetic Functionality, Helicobacter pylori inhibition and Probiotic Bifidobacterium longum Stimulation

Cherry juice from one cultivar was fermented for 0, 24, 48, and 72 h using Lactobacillus acidophilus, and its effects related to management of hyperglycemia, hypertension, inhibition of Helicobacter pylori, and proliferation of probiotic Bifidobacterium longum were evaluated using in vitro models. Cherry extract was fermented by initially adjusting the pH to 6.0 and at the natural acidic pH. Analysis was carried out by adjusting the pH and at fermented acidic pH at each time point from each of the two samples. Total soluble phenolics decreased over a period of 72 h for initial pH adjusted samples whereas it increased or remained constant for natural acidic pH samples. DPPH linked antioxidant activity and α-glucosidase inhibitory activity decreased for samples where final pH was adjusted whereas it increased for natural acidic pH samples. Fermentation led to a decrease in hypertension-relevant ACE inhibitory activity for all samples. Natural acidic pH samples had Helicobacter pylori inhibitory activity at 24, 48 and 72 h. Based on the rationale that simple phenolics in cherry could behave as proline analogs, the potential recovery of the pathogen from inhibition was evaluated with of addition of 0.5 mM proline in the medium. A proline induced growth recovery was observed indicating that the mechanism of inhibition is related to proline dehydrogenase based oxidative phosphorylation. Overall, no inhibition was observed when samples that had H. pylori inhibitory activity were further evaluated for their effect on probiotic Bifidobacterium longum.