Variation in caseinolytic properties of six cheese related Lactobacillus helveticus strains

Production of peptides and free amino acids in a sterile extract describes peptidolysis in hard-cooked cheeses

“…According to our results, proteolytic ability of the starter strains had an impact in hard cooked cheeses after several weeks of ripening, and differentiation between strains was better detected when tested in a medium in which some proteolysis had already developed and in which probably there was a higher level of the intracellular enzymes of starters. This is an important finding as proteolytic activity of lactic acid bacteria strains aimed at constituting starters is usually screened in milk (Quiberoni et al, 1998) or studied on intact caseins (Jensen et al, 2009) or intermediate-sized peptides (Oberg et al, 2002). Unfortunately, in vitro studies about these strains only assessed global proteolysis by Hull method (Quiberoni et al, 1998) and no data on their caseinolytic activities are available; consequently, is impossible to determine if a relation between caseinolytic patterns and proteolytic activity in cheese can be drawn.…”

“…This contribution varies highly from one strain to another; L. helveticus strains differentiate not only in the intensity of their caseinolytic activities but also in the specificity of their endopeptidases (Jensen, Vogensen, & Ardö, 2009). In fact, strains with equivalent proteolytic activities assessed by quantitative non-specific tests have shown significantly different hydrolysis patterns on peptides such as α s1 (f1-23) (Oberg, Broadbent, Strickland, & McMahon, 2002).…”

Simultaneous Presence of PrtH and PrtH2 Proteinases in Lactobacillus helveticus Strains Improves Breakdown of the Pure α s1 -Casein

“…In a previous study the distribution of prtH and prtH2 was shown to be strain dependent (16), with prtH2 present and expressed in all of the 29 strains studied, while prtH was present and expressed in only 18. Even though all of the strains tested possess a prtH2 gene, sequencing of an internal fragment revealed the existence of intraspecific diversity, which could be related either to two alleles of prtH2 or to another, homologous gene, such as prtH3 (3,26). Although the prtH and prtH2 genes were both shown to be expressed in dairy matrices (16) and in the absence of respective mutants, it is still difficult to distinguish the activity and specificity of each CEP.…”

“…L. helveticus strains are therefore capable of generating a diverse range of interesting textural or bioactive properties in dairy products (4,11,33). Despite the multiple technological applications of L. helveticus, little is known regarding the activity and specificity of its CEPs (23,24,26,42,45,46).…”

Effect of culturing conditions on the expression of key enzymes in the proteolytic system of Lactobacillus bulgaricus

“…The CEP activities of six L. helveticus strains on α s1 -and β-casein in MRS and milk were evaluated. It was shown that the CEPs of the different strains hydrolyzed intact α s1 -and β-casein after growth in milk, but not in MRS (Jensen et al, 2009;Griffiths and Tellez, 2013). Hébert et al (1997) showed that the effect of the growth medium on proteinase activity was evident with Lactobacillus helveticus CRL581.…”