SAFETY ASSESSMENT AND EFFECT OF SURFACTIN AND Bacillus spp. LIPOPEPTIDES ON MICROBICIDAL CAPACITY OF RAW 264.7 MACROPHAGES

DI GIACOMO, A.L; AZCURRA L.N.; GARCÍA, G.; DOGI, C.A.; GONZÁLEZ PEREYRA M.L

Jornada; XL Reunion Anual de la Sociedad de Biología de Cuyo; 2022

Bacillus species include beneficial strains that are used as probiotic additives to improve animal production for their beneficial effect though immunomodulation, reducing inflammation and protecting against enteric pathogens. Surfactin (SF) is a cyclic lipopeptide (LP) produced by Bacillus species with demonstrated anti-inflammatory, anti-microbial, anti-tumoral and immunostimulant activity. The aim of the present study was to study the biocompatibility of SF and LP extracts (LPE) from native Bacillus isolates and their effect on the phagocytic and microbicidal capacity of RAW 264.7 murine macrophages. Concentrations ranging from 10 ng/ ml to 10 µg/ml of a purified SF standard and LPE containing the same concentrations of SF (10, 50, 100 and 500 ng/ml; 1 and 10 µg/ml) were tested for cytotoxicity on RAW 264.7 cells with the MTT assay. Afterwards, non-cytotoxic concentrations were selected to perform the phagocytic and microbicidal activity tests. Macrophages were cultivated on 96-well plates and pre-treated with SF or LPE for 1 h; then 1 x 108 UFC/ml Salmonella spp. were added and incubated for 4 h. Cells were lysed and the remaining UFC/ml were counted on McConkey agar to determine microbicidal capacity. SF did not alter cell viability percentages (V%) in any of the tested concentrations. TC.12 and MFF 2.2 extracts resulted non-cytotoxic to RAW 246.7 cells, showing V% over 70 %. MF 1.11 and TC 2.5 extracts in the highest concentration resulted cytotoxic showing V