title: Oxygen-rich culture conditions enhance the conidial infectivity and the quality of two strains of Isaria fumosorosea for potentially improved biocontrol processes.
abstract: BACKGROUND
  In addition to high production levels of conidia, the success of entomopathogenic fungi as biological control agents depends both on their prevalence under the environmental conditions found in open fields (resistance to stress) and on the capacity of these conidia to infect pests. This study compares conidium production, infectivity and resistance to thermal and osmotic stress in two strains of Isaria fumosorosea (ARSEF 3302 and CNRCB1) grown either under a normal atmosphere (21% O2) or using enriched oxygen pulses (26% O2).
  
  
  RESULTS
  After 180 h, the ARSEF 3302 strain with 26% O2 pulses increased conidium production nearly fivefold compared with the normal atmosphere, while conidium production by the CNRCB1 strain decreased by 50% under O2 pulses, relative to the values measured with the normal atmosphere. The conidia obtained with 26% O2 pulses had a greater germination rate and resistance to thermal and osmotic stress, in addition to improved infectivity against Galleria mellonella (Lepidoptera) larvae. These findings were associated with an increase in catalase activities for both strains.
  
  
  CONCLUSIONS
  An enriched oxygen atmosphere increases the quality of conidia of both strains of I. fumosorosea, with a variable effect on conidium production.
authors.affiliation: Departamento de Biotecnología, Universidad Autónoma Metropolitana Iztapalapa, Mexico, DF, Mexico.
authors.forename: Francisco
authors.initials: F
authors.lastname: Miranda-Hernández
authors.forename: Gerardo
authors.initials: G
authors.lastname: Saucedo-Castañeda
authors.forename: Raquel
authors.initials: R
authors.lastname: Alatorre-Rosas
authors.forename: Octavio
authors.initials: O
authors.lastname: Loera
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D006999:Hypocreales / Q000472:pathogenicity / Q000502:physiology*; D009036:Moths / Q000382:microbiology*; D009997:Osmotic Pressure; D010100:Oxygen; D010572:Pest Control, Biological; D013172:Spores, Fungal / Q000254:growth & development*; D013696:Temperature
chemical_list: D002374:Catalase; D010100:Oxygen
keywords: catalases; cross-protection; germination; osmotic stress; oxidative stress; thermal tolerance