Isolation and Characterization of Lactic Acid Bacteria and Yeasts from Typical Bulgarian Sourdoughs

Abstract

Traditional sourdoughs in Bulgaria were almost extinct during the centralized food production system. However, a rapidly developing trend of sourdough revival in the country is setting the demand for increased production and use of commercial starter cultures. The selection of strains for such cultures is based on geographical specificity and beneficial technological properties. In this connection, the aim of this study was to isolate, identify and characterize lactic acid bacteria (LAB) and yeasts from typical Bulgarian sourdoughs for the selection of strains for commercial sourdough starter cultures. Twelve samples of typical Bulgarian sourdoughs were collected from different geographical locations. All samples were analyzed for pH, total titratable acidity and dry matter content. Enumeration of LAB and yeast was also carried out. Molecular identification by 16S rDNA sequence analysis was performed for 167 LAB isolates, and 106 yeast strains were identified by ITS1-5.8S-ITS2 rRNA gene partial sequence analysis. The LAB strains were characterized according to their amylolytic and proteolytic activity and acidification capacity, and 11 strains were selected for further testing of their antimicrobial properties. The strains with the most pronounced antibacterial and antifungal activity are listed as recommended candidates for the development of starter cultures for sourdoughs or other food products.

Characterization of technological properties of lactic acid bacteria isolated from Turkish Beyaz (white) cheese

“…The antibacterial activity of CFS was mainly due to organic acids produced by LAB. These findings are concurred with the other studies (Petkova et al, 2021;Silva et al, 2020;Suwannaphan, 2021)…”

Characterization of functional effects of different LAB isolated from sourdoughs in Turkey

“…In our study, almost all LAB showed an inhibitory effect on common pathogens following neutralization and catalase treatment. Bacteriocin-producing ability of 437 LAB isolated from 70 sourdough samples were tested (Petkova et al 2021). Whereas 85 of these strains are effective on indicator organisms without removing acids and other antimicrobial agents in cell-free supernatant (CFS), only five LAB strains inhibited indicator organisms after neutralization, catalase treatment and sterilization by filtration.…”

“…plantarum are among the most prevalent LAB present in sourdough (Minervini et al 2014). Many of the studies have focused on specific technological and nourishing effects of sourdough LAB such as proteolytic activity (Ozturkoglu-Budak et al 2016;Melini and Melini 2018), phytase activity (Cizeikiene et al 2015;Karaman et al 2018), antibacterial activity (Cizeikiene et al 2013;Petkova et al 2021), antifungal activity (Demirbaş et al 2017;Quattrini et al 2019). In addition, low pH resulting from LAB's acid production increases the activities of amylases and proteases present in the flour, thus contributing to bread rheology and flavor via influencing gluten structure (Yildirim-Mavis et al 2019).…”

Effects of Teff-Based Sourdoughs on Dough Rheology and Gluten-Free Bread Quality

“…Three lactic acid bacteria (LAB) strains were used in this study: Pediococcus acidilactici 02P108 (PA), Pediococcus pentosaceus 12R2187 (PP) and Enteroccocus durans 09B374 (ED) from the culture collection of the department of biotechnology, University of Food Technologies, Plovdiv, Bulgaria. The strains originate from typical Bulgarian sourdoughs [ 62 , 63 ]. Starter cultures for the sourdoughs were prepared from stock cultures of each strain stored in Microbank™ (Pro Lab Diagnostics Inc., Richmond Hill, ON, CA) by cultivation in MRS broth (de Man–Rogosa–Sharpe, Merck KGaA, Darmstadt, Germany) at 37 °C for 48 h.…”