Technological and Enzymatic Characterization of Autochthonous Lactic Acid Bacteria Isolated from Natural Starters.

, a Finnish ropy fermented milk, is traditionally manufactured through spontaneous fermentation, by mesophilic lactic acid bacteria and yeast-like fungi, or back-slopping. This study evaluated four natural starters as sources of lactic acid bacteria for dairy production. Back-slopping activation of the studied samples was monitored through pH and titratable acidity measurements and enumeration of mesophilic lactic acid bacteria. Sixty lactic acid bacteria isolates were collected, molecularly identified, and assayed for acidification performance, enzymatic activities, production of exopolysaccharides (EPSs), presence of the histidine decarboxylase () gene of Gram-positive bacteria, and production of bacteriocins. A neat predominance of emerged among the isolates, followed by , , , , and . Most isolates exhibited proteolytic activity, whereas only a few enterococci showed lipase activity. Five isolates identified as , , and showed a good acidification performance. Most of the isolates tested positive for leucine arylamidase, whereas only one and two isolates were positive for valine arylamidase. A few isolates also showed a positive reaction for beta-galactosidase and alpha- and beta-glucosidase. None of the isolates produced EPSs or bacteriocins. The gene was detected in five isolates identified as and . A few and isolates for potential use as starter or adjunct cultures for dairy processing were finally identified.