Preliminary characterisation of bacteriocin produced byLactobacillus acidophilus TS1 isolated from traditional dahi

Abstract

Antimicrobial activity of 79 strains of Lactobacillus isolated from indigenous dahi were tested against the indicator strains of food pathogens (Escherichia coli, Streptococcus faecalis, Staphylococcus aureus, Salmonella typhi). Among these only eleven isolates produced inhibition zones of variable size against indicator microorganisms. Later on, only one strain of Lactobacillus acidophilus (TS1) was found to produce a wider zone of inhibition against all indicator microorganisms. The antimicrobial activity of this strain was inactivated by the proteolytic enzyme proteinase K and trypsin but not by α-amylase and lipase thus confirming its proteinaceous nature. It also showed a wide range of thermostability from 70-121 °C for 15 min and retained their antimicrobial activity over a wide range of pH (3-10). The addition of bacteriocin to the earlier growth phase showed pronounced inhibition against E. coli, and Streptococcus faecalis, as compared to Staphylococcus aureus, and Salmonella typhi. The molecular weight of the substance was in the range of 7.5 kDa. This result suggested that bacteriocin might be useful as a biopreservative in different food commodities.

In vitro pre-selection criteria for probiotic Lactobacillus acidophilus TS1 isolated from fermented milk product, Dahi

“…Lactobacillus acidophilus TS1 isolate used in this research was previously isolated from the indigenous dahi (Maqsood et al, 2008). One gram of freeze-dried powder of this isolate was transferred aseptically into 50 mL sterile de Man, Rogosa and Sharpe (MRS) broth supplemented with 0.5% L (+) cysteine-HCl (99.6% purity, Sigma, USA), then incubated at 37 °C for 20 h in an anaerobic jar (Oxoid, UK).…”

“…In previous study, a total of fourteen L. acidophilus strains have been isolated from dahi. Among these, L. acidophilus TS1 strain was considered to be a potential candidate for the broad spectrum antimicrobial activity against Gram positive and Gram negative bacteria (Maqsood et al, 2008). Therefore, the present study was designed to access the some desirable probiotic traits of L. acidophilus TS1 such as acid resistance, bile tolerance, and antibiotic resistance in vitro.…”

Optimization of bacteriocin production by Lactobacillus acidophilus AA11, a strain isolated from Egyptian cheese

“…Moreover, bacteriocins retain their properties after heat treatment (Ogunbanwo et al 2003;Abdelbasset and Djamila 2008;Uymaz et al 2009;Arakawa et al 2009). They are also degraded by the proteolytic enzymes of the gastrointestinal tract and seem to be nontoxic and nonantigenic to animals and humans (Ogunbanwo et al 2003;Todorov et al 2004;Abo-Amer 2006;Maqsood et al 2008;Abdelbasset and Djamila 2008); therefore, they can be used to improve the safety and shelf life of many foodstuffs. For these reasons, bacteriocins have received much attention for use as natural or so-called 'biopreservatives' in foods in recent years (Yoneyama et al 2004;Topisirovic et al 2006;Savadogo et al 2004Savadogo et al , 2006Arakawa et al 2008;Calo-Mata et al 2008;Bhattachary and Das 2010).…”

“…Lactobacillus acidophilus is a LAB represented by many bacteriocin-producing strains (Zamfir et al 2000;Deraz et al 2007;Abo-Amer 2006;Maqsood et al 2008). It is a nonpathogenic Gram-positive bacterium, and a member of the normal intestinal microflora.…”

Indigenous Reduction of Multi-drug Resistant Bacterial Pathogens in a Natural Uncontrolled Fermented Milk Ecosystem

“…while is equivalent to yoghurt in terms of color, taste and texture (Robinson & Tamime, 2006). Studies have been elaborated the antimicrobial potential of different lactic acid bacteria isolated from the Dahi (Javed et al, 2011;Maqsood et al, 2013;Maqsood et al, 2008).…”