Cucurbit Extracts Augment Biofilm Formation by Probiotic Lactobacilli: An In Vitro Study

Gastrointestinal tract predominantly harbor trillions of microorganisms including probiotics which maintain enteric microbial homeostasis. Some dietary cucurbits were investigated for their effects on biofilm formation by Lactobacillus rhamnosus (L. rhamnosus), Lactobacillus plantarum (L. plantarum), Lactobacillus acidophilus (L. acidophilus), Escherichia coli (E. coli) and Salmonella enterica typhimurium (S. enterica typhi). Aqueous and methanol extracts of Lagenaria siceraria (Ls), Luffa cylindrica (Lc) and Cucurbita maxima (Cm) were prepared and evaluated their effective concentrations on these bacterial strains. Effective concentrations for methanol and aqueous extracts were found 93.60 μg/mL-115.40 μg/mL and 103.67 μg/mL-121.00 μg/mL, respectively. For the both types of extracts toxicity was determined up to 1 mg/mL concentration and found no microbicidal effects on probiotic strains. However, marginal inhibition on the growth of biofilms of pathogenic bacteria was observed. Extracts were found to support growth of biofilms of probiotics. Ls and Lc exhibited marginal inhibition on biofilm formation by E. coli and S. enterica typhi. Therefore, on the basis of our results it may be said that Lagenaria siceraria (bottle guard) and Luffa cylindrica (sponge guard) are safe, non-toxic and may be recommended as nutraceutical.