Effect of L. acidophilus 20552 and Bifidobacterium lactis Bb12 on rope-forming Bacillus subtillus ATCC 6633 survival during three-stages of wheat sourdough fermentation

Abstract:
This study aimed to investigate the survival of rope-forming B. subtilis ATCC6633 during three-stages of sourdough fermentation with or without L. acidophilus 20552 and/or Bifidobacterium lactis Bb12. Four strains of lactic acid bacteria are tested for their antimicrobial activities. All strains showed antimicrobial activity. L. acidophilus ATCC20552 recorded the highest inhibition zones, followed by Bf. Lactis Bb12, while both of L. acidophilus ATCC4495 and L. plantarum ATCC14917 recorded moderate activity. Sourdoughs were made using L. acidophilus 20552 and/or Bf. Lactis Bb12 with added B. subtilis ATCC6633 and fermented for 72h. Microbiological and physicochemical analyses of doughs were periodically determined. Total bacterial, yeasts and molds counts (log10 cfu/g) gradually increased by developing doughs fermentation reached the maximum at the 3rd stage. Addition of LAB strains individually or in combination recorded lower total bacterial counts and higher yeasts and moulds counts than other treatments (negative and positive control). Same trend was observed with lactic acid bacterial counts. Starter treatments recorded the highest lactic acid bacteria than both of negative and positive controls initially and during all fermentation stages. Spore forming bacteria counts were sharply decreased by developing the fermentation stage till the end of fermentation in all starter treatments, while it gradually increased in positive control (with B. subtilis ATCC 6633 only) but not in negative control. At the end of fermentation stages spore forming bacteria were not detected in starter treatments. pH values of sourdoughs sharply decreased after the 1st fermentation stage (24hrs.), while at 2nd and 3rd stages it gradually decreased till the end of fermentation. Starter treatments recorded the lowest pH values during all fermentation stages. Total titratable acidity (TTA) sharply increased after the 1st fermentation stage, continued at the 2nd and 3rd stages, these increments were higher in starter treatments than both positive and negative controls reached the maximum at the end of fermentation. In conclusion, using three-stages fermentation method give L. acidophilus 20552 and Bf. Lactis Bb12 the chance to completely inhibit rope-forming B. subtilis ATCC6633.
Publication year 2008
Organization Name
serial title Journal of Agricultural Research Kafrelsheikh University
Author(s) from ARC
Publication Type Journal
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