Growth Kinetics of Kazachstania unispora and Its Interaction with Lactic Acid Bacteria during Qymyz Production

Abstract

Qymyz is a traditional acidic and ethanolic beverage in central Asian countries made from mare milk fermentation with lactic acid bacteria (LAB) and yeasts. Modeling the growth of microorganisms during fermentation is one of the methods used to control the quality of fermented products. The objective of the study was, firstly, to model the growth kinetics of Kazachstania unispora found in qymyz, and, secondly, to understand their interaction with Lacticaseibacillus casei and Lactobacillus kefiri during the fermentation of mare milk. The K. unispora optimum values of pH and temperature were 4.81 ± 0.22 and 30.16 ± 0.53 °C, respectively, with an optimal growth rate (µopt) of 0.56 ± 0.02 h−1. K. unispora had an ethanol production rate of 6.1 × 10−8 mg·CFU−1. Growth, in terms of limiting substrates showed a lower Ks value for galactose at 0.13 ± 0.04 mg·mL−1 with µopt of 0.45 ± 0.01 h−1, while, for glucose, the Ks was 0.24 ± 0.03 mg·mL−1 with the same µopt. Cocultures of K. unispora were conducted with L. casei and L. kefiri in a synthetic medium and mare milk. The results showed that K. unispora growth was limited and, thus, its ethanol production capacity was inhibited. VOC analysis of mare milk fermented with the studied strains and their cocultures resulted in 37 major volatile compounds. Statistical analysis of the VOC profiles showed that K. unispora modulates the aroma production in coculture with LAB.

The Main Features and Microbiota Diversity of Fermented Camel Milk

“…Recent studies have underlined the role of yeasts as promising probiotics. For example, K. marxianus has the capacity to modify cell immunity, adhesion, and human gut microbiota and has antioxidative, anti-inflammatory, and hypocholesterolemic properties [78,94].…”

The complex world of kefir: Structural insights and symbiotic relationships

“…The distribution and morphological differences of LAB and yeasts on kefir grains suggest potential successional changes among community members within kefir grains. Yeasts, unable to ferment milk directly, depend on LAB to break down lactose before they play their role in the fermentation (Kondybayev et al., 2023). Results from both scanning electron microscopy and transmission electron microscopy of kefir grains reveal that yeasts attach to the surfaces of polysaccharides, proteins, and LAB following their colonization and growth (Lu et al., 2014).…”

“…Yeasts, particularly those that do not ferment lactose, not only use lactate generated by LAB as a carbon source but also metabolize it to reduce the system's acidity. Furthermore, by consuming oxygen during aerobic respiration, they establish a predominantly anaerobic growth environment favorable for LAB (Kondybayev et al., 2023; Saygili et al., 2023). In the kefir microbial community, indirect contact‐mediated transfer of resources is predominant, serving as the primary mechanism for cross‐feeding and communication among microbial communities in nature (D'Souza et al., 2018; Deng et al., 2019).…”

“…This process not only neutralizes the system's acidity but also fosters an environment conductive for the growth of LAB. Furthermore, yeasts can supply LAB with essential nutrients such as vitamins, growth factors, and amino acids (Kondybayev et al., 2023). A study employed transcriptomics to understand the interactions between S. cerevisiae and L. delbrueckii subsp .…”