Assessment of olive mill wastewaters bioconversion potential into biotechnological and health interest microbial biomass

Olive mill by-products which are characterized by powerful antioxidant and recalcitrant compounds to biodegradation represent an important environmental problem. They are produced in huge quantities in short periods of time. Therefore, finding a suitable biovalorization strategy to exploit these by-products is a great interest. In this context, the current study aimed to olive mill wastewaters (OMWW) bioconversion into valuable microbial biomass, oleaginous yeasts, as well as healthy probiotic bacteria as enrichment substrat. This study also describes and discusses the antimicrobial potential of OMWW. Yeasts and bacterial growth was monitored by plating on malt extract agar (MEA) and Man Rogosa and Sharpe Agar (MRSA) agar respectively. The antimicrobial properties of ethyl acetate polyphenolic extracts from fermented and unfermented OMWW were assessed using the disc diffusion method. The experiments trials reveals that the raw OMWW exert a strong inhibition against oleaginous yeasts and probiotic bacteria while substrate dilution or enrichment led to cell growth promoting and polyphenol removal. Moreover, polyphenolic extracts provide a wide antimicrobial spectrum potential against pathogenic and food spoiling bacteria. Thus, OMWW could be considered as a beneficial and valuable nutritional source for microbial biomass production and mainly those are of biotechnological and health interest