Semi-industrial Scale Production of a New Yeast with Probiotic Traits, Cryptococcus sp. YMHS, Isolated from the Red Sea Ashraf F. El-Baz 1 & Hesham A. El-Enshasy 2,3 & Yousseria M. Shetaia 4 & Hoda Mahrous 1 & Nor Zalina Othman 2 & Ahmed E. Yousef 5 # Springer Science+Business Media New York 2017 Abstract A new yeast strain with promising probiotic traits was isolated from the Red Sea water samples. The isolate (YMHS) was subjected to genetic characterization and iden- tified as Cryptococcus sp. Nucleotide sequence analysis of the rRNA gene internal transcribed spacer regions showed 95% sequence similarity between the isolate and Cryptococcus albidus. Cryptococcus sp. YMHS exhibited desirable charac- teristics of probiotic microorganisms; it has tolerance to low pH in simulated gastric juice, resistance to bile salts, hydro- phobic characteristics, broad antimicrobial activity, and in vitro ability to degrade cholesterol. The isolate grew well in a semi-defined medium composed of yeast extract, glucose, KH 2 PO 4 , (NH 4 ) 2 SO 4 , and MgSO 4 , yielding cell mass of 2.32 and 5.82 g/l in shake flask and in bioreactor cultures, respec- tively. Fed-batch cultivation, with controlled pH, increased the biomass gradually in culture, reaching 28.5 g/l after 32 h cul- tivation. Beside the feasible use as a probiotic, the new strain also could be beneficial in the development of functional foods or novel food preservatives. To our knowledge, this is the first report of yeast with probiotic properties isolated from the Red Sea. Keywords Cryptococcus sp. . Probiotic . Marine yeast . Biomass production Introduction The marine environment is a rich source of diverse microor- ganisms that could be of industrial importance. Marine micro- biota may produce valuable bioactive secondary metabolites [1] and generally are considered nonpathogenic to animals and humans. Therefore, microbial isolates from this environ- ment deserve investigating as probiotic candidates. The World Health Organization (WHO) and Food and Agriculture Organization (FAO) of the United Nations defined probiotics as Blive microorganisms which when consumed in adequate amounts as part of food confer a health benefit on the host^ [2]. Although numerous species of lactic acid bacteria are prominent probiotic organisms, there is an increasing in- terest in yeasts as probiotics. It is common to find yeasts with beneficial effects such as inhibition of spoilage microorgan- isms, degradation of cholesterol, and reduction of oxidative damage [3]. Yeasts are used increasingly as probiotics in the livestock and aquaculture industries where surplus biomasses from the fermentation industry are recycled as additives to cattle, pigs, and poultry diets [4, 5]. Yeasts, together with bacteria, are found in fermented dairy products and may con- tribute to the sensory characteristics of kefir, koumiss, and several cheese varieties [6]. In the human body, yeasts can grow rapidly in the intestine and produce extracellular prote- ases, siderophores, and antifungal agents [7]. These intestinal yeasts play a significant role in antagonizing undesirable mi- crobiota such as enteropathogenic bacteria [8]. Similar to the * Ashraf F. El-Baz ashraf.elbaz@gebri.usc.edu.eg; ashrafhawase@gmail.com 1 Department of Industrial Biotechnology, Genetic Engineering and Biotechnology Research Institute, University of Sadat City, Sadat, Egypt 2 Institute of Bioproducts Development, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia 3 Biopocess Development Department, City for Scientific Research, New Burg Al Arab, Alexandria, Egypt 4 Department of Microbiology, Faculty of Science, Ain Shams University, Cairo, Egypt 5 Department of Food Science and Technology, The Ohio State University, Columbus, OH, USA Probiotics & Antimicro. Prot. DOI 10.1007/s12602-017-9291-9