Brewing and Probiotic Potential Activity of Wild Yeasts Hanseniaspora Uvarum PIT001, Pichia Kluyveri LAR001 and Candida Intermedia ORQ001

Abstract

Non-conventional yeasts can be isolated from a wide range of environmental sources, often found in beverage industry in mixed fermentations, in which the microorganisms’ inoculum usually is not fully known. It is important to know starter cultures, since in addition to favoring reproducibility, other properties can be discovered. Thus, the objective of this work was to identify and characterize yeasts isolated from environment, evaluating their probiotic potential and possible use in brewery. Isolates were obtained from flowers, fruits, leaves and mixed-fermentation beers, being identified by PCR. Yeasts with promising activity were evaluated regarding their growth under different pHs, temperature and presence of organic acids. To explore probiotic potential, in vitro tests were performed of antimicrobial activity and co-aggregation with food pathogens, auto-aggregation, and survival in simulated gastrointestinal tract conditions. In our study, Pichia kluyveri (LAR001), Hanseniaspora uvarum (PIT001) and Candida intermedia (ORQ001) were selected among 20 isolates. P. kluyveri was the only one that tolerated pH 2.5. Lactic acid was not inhibitory, while acetic acid and incubation at 37 °C had a partially inhibitory effect on yeasts growth. All yeasts tolerated α-acids from hops and NaCl up to 1%. It is suggested that isolates are able to adhere to intestinal cells and influence positively the organism in combating pathogens, as they showed auto-aggregation rates above 99% and antagonistic activity to pathogenic bacteria. The yeasts tolerated gastric environment conditions, however were more sensitive to pancreatic conditions. We conclude that isolated non-conventional yeasts showed probiotic potential and promising application in beer fermentation.

Molecular and Physiological Diversity of Indigenous Yeasts Isolated from Spontaneously Fermented Wine Wort from Ilfov County, Romania

“…At concentrations lower than 2%, the response mechanism is a general one, while at higher concentrations, specific cellular response mechanisms are probably activated. Its ability to tolerate even 5% NaCl concentration is an important feature for members of this species, as previous studies have showed that H. uvarum has limited tolerance to saline stress [ 59 , 61 ]…”

“…At lower values (pH 3.0), significant growth was only recorded in the isolates H. uvarum CMGB-M1 and P. kudriavzevii CMGB-M6. The tolerance of H. uvarum CMGB-M1 to highly acidic environments it is important since another study reported that low pH values inhibit growth of the members of this species [ 61 ]. In the case of P. kudriavzevii CMGB-M6, it is not surprising that this strain showed a high ability to grow at low pH values since members of this species are well-known as being highly tolerant to stress conditions.…”