Home About us Contact
|
Home About us Contact | ||
|
|
||
Recovery Medium (recovery + medium)
Selected AbstractsEffect of sporulation and recovery medium on the heat resistance and amount of injury of spores from spoilage bacilliJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001A.E. Cazemier Aims:,To assess the influence of sporulation media on heat resistance, and the use of stress recovery media to measure preservation injury of spores of five representative spoilage bacilli. Methods and Results:,Bacillus spores prepared on nutrient agar supplemented with Ca2+, Mg2+, Mn2+, Fe2+ and K+ were more heat-resistant than spores obtained from nutrient agar with Mn2+. This increased heat resistance correlated with a decrease in the protoplast water content as determined by buoyant density sedimentation. The degree of preservation injury severity could be assessed on media containing NaCl at moderate pH and organic acids at acid pH. Ca-DPA, K+ or proline were added to the recovery media to demonstrate that heat probably caused injury to both spore germination and the outgrowth system. Significance and Impact of the Study:,The metal content of sporulation media can strongly effect the validity of preservation resistance studies. The distinctive recovery media developed here can be relevant for assessing and comparing new preservation technologies. [source] The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenesJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2000C.M.M. McMahon The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes, was examined. Exponential or stationary preconditioned cultures were heat shocked and survivor numbers estimated using selective and overlay/resuscitation recovery techniques. The results indicate that prior heat shock induced increased heat resistance in both micro-organisms to higher heat treatments. Heat-shocked cells of each micro-organism were able to survive much longer than non-heat-shocked cells when heated at 55 °C. The size of the change in heat resistance between heat-shocked and non-heat-shocked cells was greatest for exponential cultures (X:X). Results indicate that the overall relative thermal resistance of each pathogen was dependent on cell growth phase. Stationary cultures (S:S) were significantly (P < 0·01) more thermotolerant than exponential cultures (X:X) under identical processing conditions. Under most conditions, the use of an overlay/resuscitation recovery medium resulted in higher D -values (P < 0·05) compared with a selective recovery medium. [source] Antimicrobial Effects of Lactoferrin, Lysozyme, and the Lactoperoxidase System and Edible Whey Protein Films Incorporating the Lactoperoxidase System Against Salmonella enterica and Escherichia coli O157:H7JOURNAL OF FOOD SCIENCE, Issue 7 2005Seacheol Min ABSTRACT: Lactoferrin (LF), lysozyme (LZ), the lactoperoxidase system (LPOS), and edible whey protein isolate (WPI) films incorporating LPOS were studied for inhibition of Salmonella enterica and Escherichia coli O157:H7. Antimicrobial effects of LF (5 to 40 mg/mL), LZ (1 to 20 mg/mL), and LPOS (0.5% to 5.0% [w/v] [0.03,.25 g/g, dry basis]) were examined by measuring turbidity of antimicrobial-containing media after inoculation and by examining cell inhibition by WPI films incorporating LPOS (LPOS-WPI films) on an agar recovery medium. Elastic modulus (EM), tensile strength (TS), percent elongation (%E), oxygen permeability (OP), and Hunter L, a and b of WPI films incorporating 0.03 to 0.25 g/g of LPOS were compared with those of plain WPI films without LPOS. The growth of S. enterica and E. coli O157:H7 (4 log colony-forming units [CFU]/mL) in tryptic soy broth (TSB) was not prevented by LF at ,20 and ,40 mg/mL, respectively. S. enterica and E. coli O157:H7 in TSB were not inhibited by LZ at , 6 and , 20 mg/mL, respectively. LPOS at concentrations of 2.75% (w/v) and 1.0% (w/v) reduced S. enterica and E. coli O157:H7 to below the limit of detection (1 CFU/mL) in TSB, respectively. LPOS-WPI films (0.15 g/g) completely inhibited S. enterica and E. coli O157:H7 (4 log CFU/cm2), inoculated either onto agar before placing the film disc or onto top of the film disc. Incorporation of 0.25 g/g of LPOS decreased EM, TS, and %E. The oxygen barrier property of WPI films was improved with the incorporation of LPOS at 0.15 to 0.25 g/g. [source] Evaluation of spore extraction and purification methods for selective recovery of viable Bacillus anthracis sporesLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2001D.C. Dragon Aims: To investigate methods of improving anthrax spore detection with PLET. Methods and Results: Comparisons were made of PLET and blood-supplemented PLET to recover and distinguish spores of a variety of Bacillus species. Heat and ethanol purification of spores, and spore extraction from soil with water and high specific gravity sucrose plus non-ionic detergent, were also carried out. Conclusions: PLET was more selective and suitable than blood-supplemented PLET for detection of anthrax spores in the environmental specimens. However, PLET is not an optimal spore recovery medium. Purification of spores with ethanol was as effective as heat purification. High specific gravity sucrose plus detergent extraction solutions may be more sensitive than extraction with water. Significance and Impact of the Study: This study highlights shortcomings with the standard PLET isolation of anthrax spores and describes ways in which the procedure may be improved. [source] | ||||||||||