Exocellular proteases ofSerratia marcescens and their toxicity to larvae ofGalleria mellonella

Abstract

Out of 18 strains of Serratia marcescens producing exocellular proteases the strain Serratia marcescens CCEB 415 was selected according to preliminary experiments. It could be shown that the train exhibits proteolytic activity reaching up to 10 TU per 1 ml of the culture filtrate in a medium with gelatine and peptone. Two proteolytic enzyme could be demonstrated by means of specific inhibitors EDTA and diisopropyfluorophosphate: metalprotease with optimum activity at pH 7.5 and serine protease with pH optimum of 10.9. The enzymes were purified on Sephadex and DEAE cellulose columns and by means of gel electrophoresis. However, it was not possible to separate them. The optimum temperature for activity of the mixture of the two enzymes was 50degrees C, molecular weight varied around 37000 (according to gel filtration); certain kinetic characteristics of their activity were determined. Excess subtrate (casein) inhibited activity of the enzyme mixture. Toxicity of proteases expressed as LD50 units equals 78 - 10(3) TU per larva of Galleria mellonella.

Biogenesis of Outer Membrane Vesicles in Serratia marcescens Is Thermoregulated and Can Be Induced by Activation of the Rcs Phosphorelay System

“…The extracellular proteases of S. marcescens were shown to be toxic to G. mellonella (27), and these are likely the same proteases identified within the OMVs (Tables 1 and 2). A large number of other virulence-associated factors (lipases, phospholipases, and chitinases) are present in these OMVs, and therefore, it is unsurprising that they have the ability to induce larval death; however, the toxicity of S. marcescens OMV preparations to G. mellonella has not been demonstrated before, and this simple model provides a useful tool in the characterization of the role of the OMVs in pathogenesis.…”

Molecular Characterization of Protease Activity in Serratia sp. Strain SCBI and Its Importance in Cytotoxicity and Virulence

“…Expression and secretion of these exoenzymes, which includes proteases, lipases, DNases, and chitinases, are usually growth phase dependent, with activities not seen until late-exponential or stationary-phase growth (5)(6)(7)(8). In addition, expression of these exoenzymes is largely regulated by the substrate upon which they degrade (9)(10)(11). The plethora of extracellular proteins produced by Serratia spp.…”

A novel nonionic surfactant- and solvent-stable alkaline serine protease from Serratia sp. SYBC H with duckweed as nitrogen source: production, purification, characteristics and application

“…The molecular mass of the protease from Serratia sp. SYBC H is about 59 KDa, similar to that of Serratia marcescens AP3801 metalloprotease (58 kDa) [28] and Serratia marcescens HR-3 metalloprotease (61 kDa) [25], and lower than that of Serratia marcescens ATCC 25419 serine protease (66.5 kDa) [23] and Serratia rubidaea metalloprotease CP-1 (97 kDa) [29], and higher than that of Serratia marcescens metalloprotease (50 kDa) [30], Serratia marcescens NRRLB-23112 metalloprotease (50.9 kDa) [24], and Serratia marcescens CCEB 415 proteases I and II (both 37 kDa) [31]. Thus, in terms of molecular mass, the Serratia sp.…”

“…Serratia proteases that had the same optimum temperature as this protease included Serratia rubidaea protease [29], Serratia ureilytica proteases P1 and P2 [32], and Serratia marcescens AP3801 metalloprotease [28], but were lower than that of Serratia marcescens ATCC 25419 serine protease (48°C) [23], and Serratia marcescens CCEB 415 proteases I and II (both 50°C) [31]. With an approximate 20% activity at 80°C, this protease is more active at high temperatures than most of the reported Serratia proteases such as Serratia rubidaea protease metalloprotease [29], Serratia marcescens NRRLB-23112 metalloprotease [24], Serratia marcescens ATCC25419 serine protease [23], Serratia ureilytica metalloproteases P1 and P2 [32], Serratia marcescens AP3801 metalloprotease [28], Serratia marcescens CCEB 415 proteases I and II [31], all of which were completely inactivated at temperatures higher than 60 or 65°C.…”