Comparison of the Sensitivity of Phenotypic and PCR Method For The Detection Of Lactobacillus Acidophilus Isolated From Aushari Chesse

Abstract

Lactobacillus acidophilus is a Gram-positive bacterium that is associated with fermented dairy products including cheese. Methods for identifying Lactobacillus acidophilus traditionally have been used in this study based upon culture methods coupled with biochemical tests, the results show that, the selective medium(MRS) at 37OC an` aerobically had highest recovery in the isolation of L.acidophilus strains, they were rod shaped ,gram positive bacteria, catalase negative, nitrate reduction , CO2produced from glucose, indole production from treptophan, and NH3 production from arginin. Recent years have seen an explosion in the application of molecular tools for elucidating the abundance of L. acidophilus, many of these approaches, predominantly rooted in the use of ribosomal RNA (rRNA gene)in polymerase chain reaction (PCR).To develop a species-specific PCR assay for the detection of L. acidophilus in Aushari cheese samples, DNA was extracted from the pure culture then primers specific for L. acidophilus from16S rRNA genes sequence were used in PCR Reaction,the amplified products was indicated by a major amplified band ( 785 bp in size) in Agarose gel electrophoresis. The primers were shown to be specific for L. acidophilus DNA, since no PCR product was obtained when genomic DNA from other bacteria(Staphylococcus,Salmonella )were applied , This PCR assay provides a more rapid, specific and sensitive alternative to conventional culture methods for the identification of L. acidophilus without culturing of the bacteria,and can be usedfor direct identification of L. acidophilusfrom cheese and can be applied on oter kind of bacteria that are responsible of the last flavorof bacteria which is very important in cheese manefucture