Influence of culture conditions on production and freeze-drying tolerance of Paecilomyces fumosoroseus blastospores

Abstract

With the goal of developing a defined medium for the production of desiccation-tolerant blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus, we evaluated the impact of various media components such as amino acids, carbohydrates, trace metals and vitamins on hyphal growth and sporulation of P. fumosoroseus cultures and on the freeze-drying tolerance of blastospores produced under these conditions. A comparison of 13 amino acids as sole nitrogen sources showed that glutamate, aspartate, glycine and arginine supported biomass accumulations (12-16 mg ml-1) and blastospore yields (6-11 x 108 blastospores ml-1) comparable to our standard production medium which contains casamino acids as the nitrogen source. Using glutamate as the sole nitrogen source, tests with various carbohydrates showed that P. fumosoroseus grew best on glucose (18.8 mg biomass ml-1) but produced similar blastospore concentrations (7.3-11.0 x 108) when grown with glucose, glycerol, fructose or sucrose. P. fumosoroseus cultures grown in media with sodium citrate or galactose as the sole carbohydrate produced lower blastospore concentrations but more-desiccation-tolerant spores. Zinc was the only trace metal tested that was required for optimal growth and sporulation. In a defined medium with glutamate as the nitrogen source, vitamins were unnecessary for P. fumosoroseus growth or sporulation. When blastospores were freeze-dried in the absence of a suspension medium, residual glucose (>2.5% w/v) was required for enhanced spore survival. Thus, a defined medium containing basal salts, glucose, glutamate and zinc can be used to produce optimal concentrations of desiccation-tolerant blastospores of P. fumosoroseus.

Culture medium improvement for Isaria fumosorosea submerged conidia production

“…Since Zn 2+ was signed as one of the most important cations for the growth of I. fumosorosea [23] and in an earlier publication was established that a range of 10-100 M Zn 2+ was optimal for biomass production [24], a concentration of 20 mg/l of ZnSO 4 ·7H 2 O (70 M Zn 2+ ) was assumed as adequate.…”

Culture media selection for mass production of Isaria fumosorosea and Isaria farinosa

“…(formerly Paecilomyces farinosus) (Hypocreales: Cordycipitaceae) aiming to control several insect pests, due to the capacity these entomopathogens have to cause natural epizootics (Zimmermann, 2008). The capacity to grow and produce conidia in many carbon and nitrogen sources is one of the factors that make an inexpensive mass production of these fungi possible (Cliquet and Jackson, 1999). Isaria fumosorosea and Lecanicillium spp.…”

Impact of carbon and nitrogen nutrition on the quality, yield and composition of blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

“…While carbohydrates like glucose appear to enhance the desiccation tolerance of blastospores during freeze-drying [3], storage stability is unaffected.…”

“…Blastospore survival was restored when these blastospores were suspended in 2.5% glucose solution prior to freeze-drying, as previously described [3]. Other studies have also shown that the presence of glucose in the supernatant stabilized fungal cells during desiccation [2,24].…”

“…Our previous studies measured the influence of various carbon or nitrogen sources on the freeze-drying tolerance of blastospores of P. fumosoroseus [3]. In the present study, we evaluated media containing two concentrations of casamino acids and two concentrations of glucose known to impact the yield and desiccation tolerance of blastospores of P. fumosoroseus.…”