Proteolytic Activities Expressed by Gastrointestinal Pathogens Bacillus cereus, Listeria monocytogenes and Enterococcus faecium in Different Growth Phases

Abstract

AimsBacterial 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 pathogens Bacillus cereus, Listeria monocytogenes, and Enterococcus faecium in different growth phases.MethodologyBacteria 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.ResultsWe observed different active proteases with different intensities in bacteria grown to logarithmic or stationary phases. Strong activities as gelatinases were detected in B. cereus and distinct caseinolytic proteases exhibiting molecular weights of > 170 kDa, 70 kDa and 45 kDa were shown in L. monocytogenes and E. faecium, respectively. Interestingly, detected proteases were differentially regulated in bacteria grown to logarithmic or stationary phases.ConclusionIn summary, the data clearly indicated proteases that are differentially regulated in the Gram-positive pathogens B. cereus, L. monocytogenes, and E. faecium, which might contribute to bacterial pathogenesis.

Effect of Modified Pulsatilla Powder on Enterotoxigenic Escherichia coli O101‐Induced Diarrhea in Mice

“…As the conditioned pathogen of intestinal tract, Escherichia coli weakens the immunity of the organism under the imbalanced flora and triggers intestinal problems [ 47 ]. Enteric bacilli and Enterococcus are the conditioned pathogens inside the intestinal tracts [ 48 ]. Although the majority of them are normal flora of the intestinal tracts, when the host's immunity is weakened or when the bacteria relocates to the external parts, they can become conditioned pathogen, which will trigger diseases; the minority of them are pathogenic bacteria.…”

Cloning, Purification and Characterization of the Collagenase ColA Expressed by Bacillus cereus ATCC 14579

“…In a previous study, we have detected gelatinolytic activities of B . cereus ATCC 14579 in zymography analyses and which are strongly active in the logarithmic growth phase [ 35 ]. To obtain deeper insights into the molecular functions of the collagenolytic B .…”

The proteolytic activity of Listeria monocytogenes HtrA

“…In a previous study we detected unknown caseinolytic activities exhibiting a molecular weight of 70 kDa and > 170 kDa which were upregulated in the stationary growth phase of L. monocytogenes [21]. In this report, we identified active LmHtrA as the responsible protease with the molecular weight of 70 kDa for the monomer and > 170 kDa for the multimers.…”

“…Lysates of L. monocytogenes were prepared as described before [21]. 10 μg of lysates was separated by SDS-PAGE under reducing conditions and stained using 1% Coomassie Brilliant Blue G250 (BioRad, Vienna, Austria).…”