title: Proteolytic Activities Expressed by Gastrointestinal PathogensBacillus cereus,Listeria monocytogenesandEnterococcus faeciumin Different Growth Phases.
abstract: OBJECTIVE
  Bacterial proteases are implicated in protein quality control, biofilm formation or might have a direct function in pathogenesis by processing virulence factors or cleaving host factors. In recent years, knowledge of proteases expressed by Gram-negative pathogens remarkably increased. However, investigation of proteases from Gram-positive bacteria is rather rare, but required for the analysis of pathogenesis-relevant proteases. In this study, we extracted and detected proteases from the gastrointestinal pathogensBacillus cereus,Listeria monocytogenes, andEnterococcus faeciumin different growth phases.
  
  
  METHODS
  Bacteria were grown to logarithmic or stationary phases, harvested and extracted by sonication and French press. For the detection of active proteases, zymography analyses were performed using casein and gelatin as substrates to monitor caseinolytic and gelatinolytic activities.
  
  
  RESULTS
  We observed different active proteases with different intensities in bacteria grown to logarithmic or stationary phases. Strong activities as gelatinases were detected inB. cereusand distinct caseinolytic proteases exhibiting molecular weights of > 170 kDa, 70 kDa and 45 kDa were shown inL. monocytogenesandE. faecium, respectively. Interestingly, detected proteases were differentially regulated in bacteria grown to logarithmic or stationary phases.
  
  
  CONCLUSIONS
  In summary, the data clearly indicated proteases that are differentially regulated in the Gram-positive pathogensB. cereus,L. monocytogenes, andE. faecium, which might contribute to bacterial pathogenesis.
authors.affiliation: Division of Molecular Biology, Department of Microbiology, Paris-Lodron University, Salzburg, Austria.
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Abfalter
authors.affiliation: Division of Molecular Biology, Department of Microbiology, Paris-Lodron University, Salzburg, Austria.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Schmidt
authors.affiliation: Division of Molecular Biology, Department of Microbiology, Paris-Lodron University, Salzburg, Austria.
authors.forename: Silja
authors.initials: S
authors.lastname: Wessler
keywords: Bacillus cereus; Enterococcus faecium; Listeria monocytogenes; Protease; zymography