Effect of different pH values on growth and sporulation of Estye vermicola

Abstract

Esteya vermicola, an endoparasitic fungus of pinewood nematode, exhibits great potential as a biological agent against pinewood nematodes. In order to improve the growth rate, sporulation and proportion of lunate conidia, the optimization of pH value for E. vermicola was tested. The diameter and dry mass of E. vermicola in PDA medium were increased greatly at pH 5 after 15 days, while the diameter and dry mass of E. vermicola were inhibited at pH 9 and 10. The sporulation of E. vermicola in PDA or PDB medium was highest at pH 6, 2.0 × 10 7 and 1.4 × 10 7 CFU/ml, respectively. The proportion of lunate conidia in PDA medium was highest at pH 4, while the proportion of lunate conidia in PDB medium was highest at pH 7.

Effect of Ambient pH on Growth, Pathogenicity, and Patulin Production of Penicillium expansum

“…To illustrate the effect of pH on colony diameter of P. expansum, agar powder was added to 250 mL of buffered PDB media (3.5% was added to the PDB media buffered at pH 2.5 while 2% of agar powder was added to the PDB media buffered at pH 5.0, 7.0 and 8.5) in order to obtain a solid medium (PDA). After sterilization, the PDA was poured into Petri dishes, and then 5 µL of spore suspension (1 × 10 6 spore mL −1 ) was added onto the center of the solidified PDA plates and cultured for 8 days at 25 °C [ 9 ]. The colony diameter was measured each day for 8 days, and colony edges were observed under light microscope.…”

“…Determination of sporulation was according to the method of Zhen et al [ 9 ] with slight modification. P. expansum was cultured on pH-adjusted PDA for 4 and 8 days, and 40 mL of distilled water with 0.05 % ( v/v ) tween 80 was used to wash the Petri dishes, and then transferred into 50 mL tubes.…”

“…pH, the main environmental factor of this study, has significant influence on patulin production. For many cellular activities, such as development, morphogenesis, cell membrane and cell wall stabilization, protein stability and function, secondary metabolism, and host infection, ambient pH usually acts as essential signal [ 9 ]. Thus, pH acts on genes that code for patulin biosynthesis and affects gene expression of metabolic growth factors.…”

Pine Wilt Disease in Northeast and Northwest China: A Comprehensive Risk Review

“…The pathogenesis of PWD is complex, and there are many pathogenicity hypotheses, such as phytotoxin, cellulase, terpenoid, PWN, and bacteria hypotheses [54,55]. It is widely believed that PWNs and bacteria create phytotoxins and cellulases, which result in pine tree defense, the production of terpenoids, and the formation of cavities that impede water transport, and finally, pine tree wilting [54,56]. However, the critical pathogenic factor of PWD is still unknown.…”