Determination of antimicrobial, antioxidant and anticarcinogenic effects of truffle composition, lactic acid bacteria isolated from truffle and rhizosphere samples

Within the scope of this thesis, antimicrobial, antioxidant, and anticancer properties and chemical composition of cell-free extracts (CFE) from both Tuber aestivum mushrooms and lactic acid bacteria (LAB) isolated from the T. aestivum and their rhizosphere layer were investigated. Fourteen bacteria were isolated from the truffle microbiota and rhizosphere samples: 12 Enterococcus faecium and 2 Lactobacillus sakei. The inhibitory effects of CFEs of isolated LAB strains and extracts of T. aestivum species with hexane, ethyl acetate, ethanol, methanol, and water on significant pathogens were determined by well diffusion method. The highest inhibitory effect against all pathogenic strains was observed in ethyl acetate, water extracts, and (+)Tr1, (+)Tr2, (+)Tr3, and (-)Tr1 LAB's CFEs. The antioxidant activities of the selected extracts were assessed using phenolic and flavonoid content, as well as the DPPH method. The highest phenolic content (4.85 mg/g GAE) and flavonoid content (2.03 mg/g QE) were found in the ethyl acetate extract. The water extract of truffle mushrooms exhibited the highest flavonoid content at 3.19 mg/g QE. The phenolic content of (+)Tr incubated under aerobic conditions was found to be 16.94 mg/g GAE while the CFE of (-)Tr1 incubated under anaerobic conditions showed the highest level at 18.24 mg/g GAE. The highest flavonoid content was determined to be 3.99 mg/g QE for (+)Tr4. All extracts exhibited a 100% DPPH radical scavenging effect. The cytotoxicity of the extracts on cancer cell lines (HT-29 and Hep40) was determined using the MTT assay. All extracts demonstrated moderate anticancer activities against all cancer cells (p<0.05). Ethyl acetate extract showed strong antioxidant activities and revealed a 47% decrease in viability in HT-29 cells and a 34% decrease in Hep40 cells compared to control cells. The ethyl acetate extract exhibited high biological activity and contained phytochemicals such as ellagic acid, naringenin, catechin, 4-hydroxybenzoic acid, and chlorogenic acid. The selected LAB extracts showed cytotoxic effects, identified as (+)Tr1, (+)Tr2, (+)Tr3, (+)Tr4, and (-)Tr1. As a result, it was concluded that the truffle ethyl acetate extract and some E. faecium (+Tr1, +Tr2, +Tr3, +Tr4) and L. sakei (-Tr1) CFEs could be used as natural active agents.