PROTOLYTIC ACTIVITY OF CERTAIN STRAINS Of BACILLUS SPP. USED AS SUBSTITUTE FOR BUFFALOES MILK CLOTTING

The protolytic activity of 14 strains of Bacillus  spp isolated from milk samples collected  from different governorates in  Egypt was evaluated . The strains were inoculated in pasteurized  buffaloes milk incubated at 30 ^o C for 5  hours .Acidity, pH ., soluble nitrogen ( SN)  and non protein nitrogen (NPN)  as % of total nitrogen (TN) were determined during the incubation period . The tested strain showed a wide range of protolytic activity as indicated by the rate of soluble nitrogen ( SN)  and non protein nitrogen (NPN) contents  during incubation . The strain No 4,6  and 8  coagulated milk after 2 hours of incubation and showed the highest levels of both SN and NPN  content . So these strains could be recommended the production of milk clotting enzyme .
                The inhibitory affect of Lactobacillus  acidophilus , Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus  casei  subsp.  casei  on  Bacillus  were evaluated use by  diffusion  method  on  nutrient   agar media  for  the fourteen   Bacillus   spp.  It was found that the inhibtory of  Lactobacillus  acidophilus  was   more  than   Lactobacillus   delbrueckii   subsp. bulgaricus  and   Lactobacillus   casei    subsp.  casei   except on  B . sphaercus . The inhibitory  effects of  L.  acidophilus  ;  L. delbrueckii   subsp.  bulgaricus    and   Lactobacillus  casei  subsp.  casei  was the same. Further mores the  effect of heat treatment  within  the temperature range of  85-135 ^o C. , and   various  exposure  times  was  studied  . The highest  resistance was  found in case of    B .  amyloliquficans  spores , which survived the temperature  of  135 ^o C.  the  greatest  reduction of spore  numbers was  found for B .cereus .