Absence of oxygen associated with cold caused a decrease in growth ability of B. cereus. Following growth by CFU counting showed no growth of fermentative cultures at 15 C, although growth could be measured by A600. CFU counts and A600 measurements of fermentative and aerobic cultures at 37 C and aerobic cultures at 15 C increased with time, so that growth of
B. cereus could be measured in these conditions with both methods. Cold alone caused a slight increase in CFU size (ten times fewer CFUs per A600 unit), but not fermentation without cold (same number of CFUs per A600 unit in aerobic and fermentative cultures at optimal temperature). As cold with fermentation caused an increase in the CFU size (100 times fewer CFUs per A600 unit than at optimal temperature), we can conclude that cold and fermentation increased CFU size synergistically. A synergy of the two conditions to reduce biomass production was observed by de Sarrau et al.(2012). Microscopic observation confirmed the variation in CFU size over the different growth conditions, with cell lengths from 4 mm to at least 170 mm. The formation of long cells in cold fermentative cultures was observed for two strains and two different media. In addition, a specific alteration of morphologywas observed in cold aerobic cultures. Light microscopy observations made by den Besten et al. (2009) during growth of B. cereus in salt stress conditions permitted to see the individual cells forming the filaments. In our study, light microscopy did not permit to distinguish the separated cells.
Absence of oxygen associated with cold caused a decrease in growth ability of B. cereus. Following growth by CFU counting showed no growth of fermentative cultures at 15 C, although growth could be measured by A600. CFU counts and A600 measurements of fermentative and aerobic cultures at 37 C and aerobic cultures at 15 C increased with time, so that growth of
B. cereus could be measured in these conditions with both methods. Cold alone caused a slight increase in CFU size (ten times fewer CFUs per A600 unit), but not fermentation without cold (same number of CFUs per A600 unit in aerobic and fermentative cultures at optimal temperature). As cold with fermentation caused an increase in the CFU size (100 times fewer CFUs per A600 unit than at optimal temperature), we can conclude that cold and fermentation increased CFU size synergistically. A synergy of the two conditions to reduce biomass production was observed by de Sarrau et al.(2012). Microscopic observation confirmed the variation in CFU size over the different growth conditions, with cell lengths from 4 mm to at least 170 mm. The formation of long cells in cold fermentative cultures was observed for two strains and two different media. In addition, a specific alteration of morphologywas observed in cold aerobic cultures. Light microscopy observations made by den Besten et al. (2009) during growth of B. cereus in salt stress conditions permitted to see the individual cells forming the filaments. In our study, light microscopy did not permit to distinguish the separated cells.
การแปล กรุณารอสักครู่..
