الفهرس 
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Abstract
Pickles samples were collected from many cities of Sharkia Governorate. Pickles types were onion, olive, pepper, carrot, turnip, cucumber or mixed pickles. Fourty five bacterial isolates were isolated onto nutrient agar medium and fivteen lactic acid bacterial isolates were isolated and enumerated on MRS agar. All bacterial isolates were surveyed for their ability to produce inhibitory substances by both disc and agar well diffusion assays. Isolate no. 10 which designated LPS10 inhibited all indicator strains used except for Pseudomonas aeruginosa. Four bacterial isolates growing on nutrient agar which designated BPS4, BPS13, BPS20 and BPS33 inhibited some pathogenic bacteria.
The five biologically active bacterial isolates were subjected to characterization and identification studies. Biochemical methods of identification were, preliminary, followed. The LPS10 isolate was classified and identified as belonging to L. plantarum and designated L. plantarum LPS10. However, the bacterial isolates BPS4, BPS13, BPS20 and BPS33 were classified and identified as belonging to B. acidicola, B. aerophilus, B. amyloliquefaciens and B. mycoides and designated B. acidicola BPS4, B. aerophilus BPS13, B. amyloliquefaciens BPS20, B. acidicola BPS30 respectively. The molecular characterization and their identification by genetic fingerprint using 16S rRNA proved the biochemical identification.
It was important to characterize the antimicrobial substance(s) produced by L. plantarum LPS10. The antimicrobial substance was heat resistant, degraded by proteolytic enzymes, resistant to action of lipase, amylase and organic solvents and, consequently, coupled with most definitions of bacteriocins and could be, hence, classified as a bacteriocin. The production of this bacteriocin was optimum at initial pH 6.5 and at incubation temperature of about 35C when the producer organism was in tThe L. plantarum LPS10 strain grew well in MRS broth and acidified the medium rapidly and final pH reached 3.6 after 12h, produced protease, esterase, amylase and glucosidase and hence could be used as probiotic and protective culture during pickles fermentation thoroughly with starter capabilities. It also produced acetoin which could give the final food product distinctive flavour. The identified Bacillus strains BPS4, BPS11, BPS20 and BPS33 inhibited some pathogenic bacteria, tolerated NaCl up to 12%, grew well in nutrient broth and produced also acetoin and, consequently, could be used for aroma production in food; theshe mid to the late exponential phase of growth. could be used as biocontrol agents during pickles making.
It was important to characterize the antimicrobial substance(s) produced by L. plantarum LPS10. The antimicrobial substance was heat resistant, degraded by proteolytic enzymes, resistant to action of lipase, amylase and organic solvents and, consequently, coupled with most definitions of bacteriocins and could be, hence, classified as a bacteriocin. The production of this bacteriocin was optimum at initial pH 6.5 and at incubation temperature of about 35C when the producer organism was in the mid to the late exponential phase of growth.