The gastrointestinal tract (GIT) contains trillions of microorganisms with over 1000 bacterial species, including probiotic bacteria. Gut microbes, including probiotic species, help build the immune system, protect against pathogens, and synthesize nutrients. Lactobacillus is a genus of gram-positive bacteria and comprises a major part of the lactic acid bacteria group that converts sugars to lactic acid. Lactobacillus species are accepted to be beneficial to human health and are often used in probiotic formulations, but their functions remain poorly defined. There is a significant need to understand molecular mechanisms underlying the impacts of probiotics to develop novel therapeutics to address antibiotic resistance or optimize medical treatment based on individual characteristics, such as diet, microbiota composition, and antibiotic treatment. Lactobacillus levels in the microbiota are often affected by the dietary abundance of essential metals such as zinc. Zinc deficiency is linked to gastrointestinal diseases and an impaired immune system, while zinc overload is associated with increased infection susceptibility. Zinc is known to play cellular signaling roles and is an important structural and catalytic cofactor in thousands of proteins, but few studies have considered the role of metals and especially zinc in Lactobacillus species. The ability of bacteria to form biofilms that enhance GIT colonization is a likely prerequisite for probiotic effectiveness, and metal interactions with surface proteins may mediate this biofilm formation. Here we investigated metal uptake and the role of zinc in the growth kinetics and biofilm formation of two distinct species of Lactobacillus with different surface proteins. We observed distinct zinc-dependent patterns in growth and biofilm formation for Lactobacillus plantarum ATCC 14917 and Lactobacillus acidophilus ATCC 4356. Zinc (50-100 µM) can promote the growth kinetics of both Lactobacillus species and the formation and viability of their biofilms. The effect of zinc on the growth kinetics and biofilm formation of Lactobacilli is strongly influenced by the culture media.

Uncovering the role of zinc in growth, metal uptake, and biofilm formation of probiotic Lactobacillus species

ACS Spring Meeting 2021

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