Effect of pH on the growth of three lactic acid bacteria strains isolated from sour cream

Abstract

Lactic acidbacteria(LAB)haveanimportantroleinthefoodindustry because theyareusedintheproductionoffermentedfoods.Touse thesemicroorganismsinthefoodindustry,itisnecessarytoobtaina high amountofbiomass.Oneofthemostimportantenvironmental factorsinthegrowthofLABispH.MostofLABspeciescantolerate a pHbelow5.0,however,asuboptimalpHisexpectedtolimitLAB growth.Forthisreason,theLABstrains Leuconostocmesenteroides 67-1, Lactobacillusplantarum 60-1, and Streptococcusinfantarius 46-3, isolated fromsourcream,weregrowninculturemediaunderfourdifferent intial pHvaluestodeterminetheiroptimalgrowthpH.Growthwas assesed viacolony-formingunit(CFU/ml) determination.Wefound thatthegrowthofeachLABwasaffectedbyculturemediumpH.We determinedthatthesetpointsofpHfor Leuconostocmesenteroides 67-1, Streptococcusinfantarius 46-3, and Lactobacillusplantarum 60-1 wereof 4.5 (±0.5), 5.5(±0.5), and6.0(±0.5), respectively.Wethusconclude thatthegrowthoftheseLABstrainsispH-dependent(p < 0.05).