Extractive fermentation of gibberellic acid with free and immobilized Gibberella fujikuroi.

Gibberelic acid fermentation using extractive methods was carried out in the presence of corn oil and Alamine 336. Gibberella fujikuroi fungus (NRRL 2278) was used to produce gibberellic acid. Oleyl alcohol was a diluting agent for Alamine 336. The effects of oleyl alcohol (100%, v/v), corn oil (5-25%, v/v), the concentration of Alamine 336 in oleyl alcohol, and feeding air were examined in this study. According to the results, oleyl alcohol was not effective on the production. On the other hand, oleyl alcohol solutions containing 15-30% (v/v) Alamine 336 showed effects as a toxic substance. In order to reduce solvent toxicity, corn oil was used. Addition of corn oil increased the concentration of gibberellic acid 1.3-fold compared to the control. Then the effects of immobilization and co-immobilization on extractive gibberelic acid fermentation were investigated. The highest total gibberellic acid concentration of 158.9 mg/L was produced with immobilized cells and feeding air by using extractive fermentation. The yield of gibberellic acid increased about 2.6-fold compared with the shake-flask fermentation (60.5 mg/L) without organic solutions.

A new pyrrolidine derivative and steroids from an algicolous Gibberella zeae strain.

A new pyrrolidine derivative, 3-hydroxy-5-(hydroxymethyl)-4-(4'-hydroxyphenoxy)pyrrolidin-2-one (1), and eight known steroids, (22E,24R)-7beta,8beta-epoxy-3beta,5alpha,9alpha-trihydroxyergosta-22-en-6-one (2, a reassigned structure of (22E,24R)-5alpha,6alpha-epoxy-3beta,8beta,14alpha-trihydroxyergosta-22-en-7-one), (22E,24R)-3beta,5alpha,9alpha-trihydroxyergosta-7,22-dien-6-one (3), (22E,24R)-3beta,5alpha-dihydroxyergosta-7,22-dien-6-one (4), (22E,24R)-ergosta-7,22-dien-3beta/,5alpha,6beta-triol (5), (22E,24R)-ergosta-5,22-dien-3beta-ol (6), (22E,24R)-5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol (7), (22E,24R)-5alpha,8alpha-epidioxyergosta-6,9(11),22-trien-3beta-ol (8), and (22E,24R)-1(10 --> 6)-abeo-ergosta-5,7,9,22-tetraen-3alpha-ol (9), were isolated from the cultures of Gibberella zeae, an endophytic fungus isolated from the marine green alga Codium fragile. Their structures and relative stereochemistry were elucidated by 1D, 2D NMR and mass spectroscopic techniques. Compound 1 showed cytotoxicity against A-549 and BEL-7402 cell lines.

Comparative mycotoxin profiles of Gibberella zeae populations from barley, wheat, potatoes, and sugar beets.

Gibberella zeae is one of the most devastating pathogens of barley and wheat in the United States. The fungus also infects noncereal crops, such as potatoes and sugar beets, and the genetic relationships among barley, wheat, potato, and sugar beet isolates indicate high levels of similarity. However, little is known about the toxigenic potential of G. zeae isolates from potatoes and sugar beets. A total of 336 isolates of G. zeae from barley, wheat, potatoes, and sugar beets were collected and analyzed by TRI (trichothecene biosynthesis gene)-based PCR assays. To verify the TRI-based PCR detection of genetic markers by chemical analysis, 45 representative isolates were grown in rice cultures for 28 days and 15 trichothecenes and 2 zearalenone (ZEA) analogs were quantified using gas chromatography-mass spectrometry. TRI-based PCR assays revealed that all isolates had the deoxynivalenol (DON) marker. The frequencies of isolates with the 15-acetyl-deoxynivalenol (15-ADON) marker were higher than those of isolates with the 3-acetyl-deoxynivalenol (3-ADON) marker among isolates from all four crops. Fusarium head blight (FHB)-resistant wheat cultivars had little or no influence on the diversity of isolates associated with the 3-ADON and 15-ADON markers. However, the frequency of isolates with the 3-ADON marker among isolates from the Langdon, ND, sampling site was higher than those among isolates from the Carrington and Minot, ND, sites. In chemical analyses, DON, 3-ADON, 15-ADON, b-ZEA, and ZEA were detected. All isolates produced DON (1 to 782 microg/g) and ZEA (1 to 623 microg/g). These findings may be useful for monitoring mycotoxin contamination and for formulating FHB management strategies for these crops.

Induction of a polyubiquitin gene (ubi1) by potato phytoalexins and heat shock in Gibberella pulicaris.

Gibberella pulicaris, a causal agent of potato dry rot, infects potato tubers via wounds, where it is exposed to the phytoalexins rishitin and lubimin. Incubation of mycelium on agar supplemented with phytoalexins transiently induced the transcription of a polyubiquitin gene consisting of four ubiquitin units arranged head to tail; the fourth unit contains a 54-bp intron and an additional glutamine at the C-terminus of the encoded protein. Southern analysis of the G. pulicaris genome revealed one copy of the isolated polyubiquitin gene and one or two copies of other ubiquitin genes. Increased transcription of the gene was detectable above a threshold of 100 microg/ml of rishitin and at elevated temperatures, which indicates that exposure to phytoalexins causes a stress reaction of hyphal cells similar to that after heat shock.