Identification of lactic acid bacteria from the crust and inner part of artisanally produced mihaliç cheese sold with salty and low salty label by using maldi-tof-ms and 16s rdna sequencing

Abstract

Mihaliç is a traditional cheese manufactured using artisanal methods without adding starter cultures from a mixture of sheep'sand cow's milk. The indigenous microbiota originating from raw milk and the surrounding environment, which adapt to theripening conditions, play a crucial role in developing the artisanal cheeses' characteristic flavor, aroma, and texture. In this study,the lactic acid bacteria in both the crust and the inner part of Mihaliç sold under the label of Salty Mihaliç Cheese (SMC) andLow-Salty Mihaliç Cheese (LSMC) were determined using MALDI-TOF MS analysis and 16S rDNA sequencing. The enumera-tion of Streptococcaceae on M17 agar revealed approximately a 2-log higher count compared to Lactobacillus and Enterococcuspopulations. Among the isolates recovered from M17 medium, Lactococcus lactis was identified as the predominant species,comprising 43.7% of the total. Notably, consistent with observations in many other artisanal raw milk cheeses, Streptococcusgallolyticus subsp. macedonicus and Streptococcus infantarius subsp. infantarius were also detected at high frequencies, with41.2% and 7.5% prevalence rates, respectively. Among the enterococci, Enterococcus faecium and Enterococcus faecalis werethe most frequently isolated species, accounting for 43.5% and 42.2% of the isolates, respectively. Regarding the distribution oflactobacilli, Lacticaseibacillus casei/paracasei and Limosilactobacillus fermentum emerged as the dominant species, exhibitingprevalence rates of 47.1% and 35.2%, respectively. Meanwhile, comparative analysis between SMC and LSMC cheese samplesshowed that Lim. fermentum was more abundant in SMC samples (55.1%), whereas Lcb. paracasei/casei was dominant in LSMCsamples (55.9%). Furthermore, both Lim. fermentum and Lcb. rhamnosus were more frequently recovered from the inner part ofthe cheese matrix. These findings highlight the complex and diverse lactic microbiota of Mihaliç cheese, which is likely to play asignificant role in the development of its unique flavor and textural characteristics.