Screening for proteolytically active lactic acid bacteria and bioactivity of peptide hydrolysates obtained with selected strains

Abstract

In a screening for proteolytically active lactic acid bacteria, three strains, Lactobacillus delbrueckii ssp. lactis 92202, Lactobacillus helveticus 92201, and Lactobacillus delbrueckii ssp. bulgaricus 92059, showed the highest activities following growth in milk. All three strains degraded α- and β-casein, but did not hydrolyse κ-casein. HPLC analysis of skim milk fermentation revealed increasing amounts of peptides after 5 and 10 h with Lb. d. ssp. bulgaricus 92059. Hydrolysates obtained with Lb. d. ssp. lactis 92202 and Lb. d. ssp. bulgaricus 92059 revealed the highest angiotensin-converting enzyme-inhibitory effect. The effect was dose dependent. Almost no effect (<10%) was seen for Lb. helveticus 92201. For Lb. d. ssp. bulgaricus 92059, maximal inhibition of approx. 65% was reached after 25 h of fermentation. In an in vitro assay measuring potential immunomodulation, hydrolysates of the three strains yielded anti-inflammatory activities in the presence of TNF-α. However, the effects were more pronounced at lower hydrolysate concentrations. In the absence of TNF-α, slight pro-inflammatory effects were observed. The hydrolysate of Lb. d. ssp. bulgaricus 92059, when purified by means of solid-phase extraction, exhibited pro-inflammatory activity. Sour whey containing Lb. d. ssp. bulgaricus 92059 cells showed pro-inflammatory activity while cell-free sour whey was clearly anti-inflammatory. In the purified hydrolysate, 20 different α- and β-casein (CN)-derived peptides could be identified by LC-MS. Most peptides originated from the central and C-terminal regions of β-casein. Peptide length was between 9 (β-CN(f 59-67)) and 22 amino acids (β-CN(f 117-138)).

Lactic acid bacteria isolated from dairy products as potential producers of lipolytic, proteolytic and antibacterial proteins

“…Previous studies have failed to consider both lipolytic and proteolytic activities concurrently. Some studies focusing on other fermented products, such as wine or meat, screened for either the lipolytic or proteolytic activity of bacteria (Kliche et al 2017 ; Pérez-Martín et al 2013 ). In this study, 137 strains isolated from dairy products were screened for both lipolytic and proteolytic activities.…”

“…This indicates that more than half of the LAB isolated from these dairy products have proteolytic activity and likely a direct effect on sensory properties, such as flavor formation and aroma in ripening foods (Simitsopoulou et al 1997 ). The hydrolysis of proteins in milk (i.e., casein, ß-lactoglobulin, and α-lactalbumin) produces free amino acids and small peptides, which have been suggested to exhibit anti-inflammatory and antioxidant effects in humans (Kliche et al 2017 ). Furthermore, these hydrolyzed peptides are beneficial to gut microbiota because they show antimicrobial activity and inhibit pathogenic microorganisms such as E. coli , L. monocytogenes , and S. aureus , thereby promoting the growth of LAB (Mohanty et al 2016 ).…”

“…Out of all LAB, the proteolytic system of Lactococcus lactis is the most extensively studied in terms of regulation and hydrolysis of milk proteins as casein (Savijoki et al 2006 ). Also, the Lactobacillus genus, specifically L. delbrueckii and L. helveticus , produce proteases that can hydrolyze α- and ß-casein (Kliche et al 2017 ). The Pediococcus genus displays high levels of proteolysis and is commonly found in meat and cheese products (Gandhi et al 2016 ; Simitsopoulou et al 1997 ).…”

Multi-Functional Potential of Presumptive Lactic Acid Bacteria Isolated from Chihuahua Cheese

“…Antioxidant activities were demonstrated by the inhibition of the ABTS + and DPPH + radicals, using the supernatants obtained by presumptive LAB fermentation of casein-peptone broth. Casein-skimmed milk media has already been used to study the production of antioxidant peptides; however, each strain or even the breaking down method (e.g., enzymatic) could have different patterns of hydrolysis and release different peptides with different bioactivities [43]. The molecular weight, the amino acid composition and sequence, as well as the secondary structure and stability of the bioactive peptides obtained by proteolytic activity of the isolates are important factors that affect antioxidant properties [44]; thus, further studies are needed to explain differences in antioxidant activity.…”

Production of Bioactive Peptides by Lactobacillus Species: From Gene to Application

“…delbrueckii subsp. bulgaricus , presenting ACE inhibitory and immunomodulatory capacities, was lyophilized and used as a nutraceutical for yogurt ( Kliche et al, 2017 ).…”