Abstract
The ability of sublethally heat-stressed aleuriospores of Chrysosporium farinicola to form colonies on yeast extract-glucose agar (YGA) supplemented with sufficient glucose, sorbitol, glycerol, and NaCl to achieve reduced water activity (aw) in the range of 0.88 to 0.95 was determined. The effects of the aw of diluent and incubation temperature during recovery and colony formation were also investigated. Aleuriospores harvested from 14-day-old cultures grown at 25 degrees C were less resistant to heat inactivation compared with aleuriospores from 20-day-cultures. Increased populations of heat-stressed aleuriospores were recovered as the aw of YGA was decreased from 0.95 (glucose and glycerol) and 0.94 (sorbitol) to 0.89 and 0.88, respectively. In NaCl-supplemented YGA, populations recovered at an aw of 0.94 were greatly reduced compared with populations detected at an aw of 0.92; no colonies were formed on NaCl-supplemented YGA at an aw of 0.88. Tolerance to aw values above 0.88 to 0.89 as influenced by solute type was in the order of glucose greater than sorbitol greater than glycerol greater than NaCl. Incubation at 20 degrees generally resulted in an increase in recoverable aleuriospores compared with incubation at 25 degrees C or at 30 degrees C for 14 days followed by 20 degrees C for 10 days. The lethal effect of NaCl on heat-stressed aleuriospores was enhanced at 30 degrees C. The retention of viability of aleuriospores held in sucrose-peptone water diluent (aw, 0.936) for 20 min was essentially the same as that observed when aleuriospores were held in peptone water (aw, 0.997).(ABSTRACT TRUNCATED AT 250 WORDS)
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Beuchat L. R. Combined effects of solutes and food preservatives on rates of inactivation of and colony formation by heated spores and vegetative cells of molds. Appl Environ Microbiol. 1981 Feb;41(2):472–477. doi: 10.1128/aem.41.2.472-477.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Beuchat L. R. Injury and repair of yeasts and moulds. Soc Appl Bacteriol Symp Ser. 1984;(12):293–308. [PubMed] [Google Scholar]
- Beuchat L. R., Pitt J. I. Influence of solute, pH, and incubation temperature on recovery of heat-stressed Wallemia sebi conidia. Appl Environ Microbiol. 1990 Aug;56(8):2545–2550. doi: 10.1128/aem.56.8.2545-2550.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hocking A. D., Pitt J. I. Dichloran-glycerol medium for enumeration of xerophilic fungi from low-moisture foods. Appl Environ Microbiol. 1980 Mar;39(3):488–492. doi: 10.1128/aem.39.3.488-492.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pitt J. I., Christian J. H. Water relations of xerophilic fungi isolated from prunes. Appl Microbiol. 1968 Dec;16(12):1853–1858. doi: 10.1128/am.16.12.1853-1858.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pitt J. I., Hocking A. D. Influence of solute and hydrogen ion concentration on the water relations of some xerophilic fungi. J Gen Microbiol. 1977 Jul;101(1):35–40. doi: 10.1099/00221287-101-1-35. [DOI] [PubMed] [Google Scholar]