Abstract
<p>Probiotic extracts can potentially be used as bio-preservatives and in reduction of oxidative stress. The study investigated the antibacterial and antioxidant activity of methanol extracts from freeze-dried cells of probiotic <em>Lactobacillus</em> strains identified using molecular techniques. The quantitative microplate method, which employed <em>p</em>-iodonitrotetrazolium (INT) and the method by Brand-Williams et al. (1995) were employed to investigate quantitatively the antibacterial and the antioxidant activity, respectively, of probiotic extracts. The MIC values extracts from most probiotic strains, tested against indicator bacterial pathogens, were in the range of 1.25 – 5 mg/mL while that of <em>Lb. casei</em> strain B and <em>Lc. lactis</em> subsp <em>lactis</em> strain X was at least 20 mg/mL after 24 h of incubation at 37°C. At the highest extract concentration of 20 mg/mL used in the study, <em>Lb. acidophilus</em>, <em>Lb. rhamnosus</em> and <em>Lb. casei</em> strains had 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities of 77.9 - 86.1%, 45.7 - 86.4% and 36.9 – 45.8% respectively. Quantitative antibacterial and antioxidant activities of methanol extracts from freeze-dried cells of probiotic <em>Lactobacillus</em> strains was determined for the first time.</p>
Highlights
Probiotics are defined as ‘live microorganisms of human intestinal origin, which, in adequate quantities, impart health benefits to the consumer beyond basic nutrition’ (FAO/WHO, 2002)
This suggests that the consumer of selected probiotic strains may benefit through oxidative stress reduction
This study investigated possible antibacterial activity and antioxidant activity of methanol extracts from freeze-dried cells of probiotic Lactobacillus strains
Summary
Probiotics are defined as ‘live microorganisms of human intestinal origin, which, in adequate quantities, impart health benefits to the consumer beyond basic nutrition’ (FAO/WHO, 2002). The potential health benefits of probiotics include improvement in gut health and lactose intolerance, prevention of diarrhoea, constipation alleviation, reduction in serum cholesterol, prevention of vaginitis and intestinal infections, management of diabetes mellitus, prevention of hepatic diseases and inflammatory bowel disease, risk reduction in colon tumours and cancer, oxidative stress reduction and host immune system modulation (Marchand & Vandenplas, 2000; Holzapfel & Schillinger, 2002; Blandino et al, 2003; Franz et al, 2003; Rousseau et al, 2005; Shen et al, 2011; Ejtahed et al, 2012; Li et al, 2012; Sharma et al, 2014; Nyanzi et al, 2014). Antibiotics can reduce infections, antibiotic resistance as in the case of methicillin-resistant Staphylococcus aureus implies that there is a need to have alternative pathogen inhibitors (Yasunaka et al, 2005)
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