Student Research

The Effect of Nicotine on the Sporulation and Growth of Bacillus subtilis

Nicotine is the addictive chemical in tobacco and smokers experience greater infections and illnesses. Bacillus subtilis (BS) is considered a probiotic spore forming bacteria, which is present in the human body. Sporulation is a resilient life stage that allows the bacteria to endure unfavorable conditions and germinate during better conditions. The objective of this study is to observe the effect of nicotine on the BS. Bacteria grown in the presence of varying concentrations of nicotine ranging from 1x10-15 M to 1x10-1 M in both TSB and TGY was examined for sporulation and growth at 24, 48 and 72 hours. BS grown in the absence of nicotine in TSB did not form spores at 24, 48 and 72 hours, while the TSB with nicotine had a significantly higher amount of spores at all nicotine concentrations at 48 and 72 hours. Sporulation occurred in the BS grown on the TGY plates without nicotine. This is probably because TGY has fewer nutrients in the media, making it a less hospitable environment for the BS. The growth of the BS was not affected by the presence of nicotine in TSB, but was enhanced in TGY at 1x10-15 M and suppressed at 1x10-1 M, suggesting a biphasic growth regulation of BS in TGY but not in TSB. The current findings indicate that nicotine induces greater sporulation of BS, which could reduce the beneficial effect of the presence of BS in the body as probiotic bacteria. The exact mechanism to elucidate the difference between the two media will require further investigations.

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