Influence of growth conditions on the production of extracellular proteolytic enzymes in Paenibacillus peoriae NRRL BD-62 and Paenibacillus polymyxa SCE2

AIMS: To analyse the extracellular protease profile of two Paenibacillus species, Paenibacillus peoriae and Paenibacillus polymyxa, as well as how different growth media influenced its expression. METHODS AND RESULTS: Both bacteria were cultured in five media Luria-Bertani broth, glucose broth, thiamine/biotin/nitrogen broth (TBN), trypticase soy broth and a defined medium] for 48 h at 32 degrees C. Our results showed a heterogeneous protease secretion pattern whose expression was dependent on medium composition. However, TBN induced the most quantitative and qualitative protease production on both Paenibacillus. The proteases were detected in neutral-alkaline pH range, being totally inhibited by 1,10-phenanthroline, a zinc-metalloprotease inhibitor. We also analysed the protease expression during the growth and, at least to P. peoriae, the most elevated protease activity was measured at 96 h, in which the highest number of spores and a low concentration of viable cells were observed. CONCLUSIONS: The results presented add P. peoriae and P. polymyxa to the list of neutral-alkaline extracellular protease producers. SIGNIFICANCE AND IMPACT OF THE STUDY: Paenibacillus species are ubiquitous in nature, are capable to form resistant spores and to produce several hydrolytic enzymes, including proteases. However, only few data concerning the production of these enzymes are available. Proteases produced by Paenibacillus strains may represent new sources for biotechnological use.