Purification and characterization of the cuticle-degrading proteases produced by an isolate of Beauveria bassiana using the cuticle of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae)

Abstract

The entomopathogenic fungi-like Beauveria bassiana must penetrate via the integument of an insect to reach the hemocoel. Since proteins are the molecules responsible for integument strength in insects, the proteins must synthesise the cuticle degrading proteases which will then enable the proteases to penetrate. It is important to determine the biochemical properties of these proteases so that fungal virulence can be better understood. In the current study, a recently collected isolate of B. bassiana, namely AM-118, was inoculated in liquid media containing 0.5% of Andrallus spinidens Fabricus cuticle to obtain specific proteases. The crude samples were purified via a three step process using ammonium sulfate, Sepharyl G-100, and DEAE-Cellulose Fast Flow. The results revealed two proteases known as subtilisin-like (Pr1), and trypsin-like (Pr2), with the molecular weights of 105 and 103 kDa. The optimal pH and temperature values were found to be 8 and 35°C for Pr1 and 8 and 40°C for Pr2, respectively. Inhibitors like AEBSF, EDTA, TPCK, and phenanthroline significantly affected proteolytic activities. Here, we reported two fungal proteases by high molecular weight from an Iranian isolate of B. bassiana. These findings will help us to better understand fungal virulence against insects.

Journal of Plant Protection Research

“…In detail, the numbers of total and differentiate hemocyte counts altered following isolate injection at different time intervals in addition to phenoloxidase activity. These results concurred with earlier findings on different virulence of BB 2 and AM-118 against A. spinidens (Firouzbakht et al 2016).…”

“…Virulence of the two isolates of B. bassiana and immune responses of A. spinidens were determined in two studies by Firouzbakht et al (2015Firouzbakht et al ( , 2016. The LC 50 concentrations of the isolates BB 2 and Am-118 were calculated as 37 × 10 5 and 15 × 10 3 conidia • ml -1 .…”

The effect of sublethal doses of Bacillus thuringiensis Berliner on Tuta absoluta (Meyrick) on resistant and susceptible tomato cultivars

“…The amount of this enzyme is very low in the hemolymph of healthy insects but increases rapidly in the insects infested with fungi or other pathogens (Cerenius et al, 2008). Similar results have been reported for some pests such as Eurygaster integriceps (Zibaee et al, 2011) and Andrallus spinidens (Firouzbakht et al, 2016).…”