Some Nutritional Factors Affecting Production of Biomass and Antifungal Metabolites of Coniothyrium minitans

Abstract

The ability of the mycoparasit e Coniothyriu m minitans to utilize a range of C and N sources and vitamins for growth, pycnidia l formation and antifunga l metabolite production was examined using a deWned liquid medium. Coniothyriu m minitans was able to use all the C sources tested, with the exception of d-xylose, and all the N sources tested, although growth was generally better on organic N sources rather than NO 3 ± N. Increasing C:N ratios from 9:1± 202:1 with N constant (2.0 g L 2 l l-alanine) resulted in steadily increasing yields, whereas increasing C:N ratios with C constant (40.0 g L 2 l d-glucose) gradually decreased yield. Addition of thiamine to the glucose± alanine basal medium resulted in the greatest increase in growth but biomass was still less than that achieved using an undeWned molasses± yeast medium. Pycnidial production was generally low or failed to occur in the basal medium + C + N sources in the absence of vitamins, but addition of thiamine consistently led to abundan t pycnidial formation. Molasses± yeast static culture provided greater biomass and conidial yields than molasses± yeast shaken culture. Incorporation of C. minitans culture medium into potato dextrose broth (10% v/v) resulted in consistent reduction in growth of Sclerotinia sclerotiorum irrespective of C, N or vitamin content of the basal medium or whether molasses± yeast medium was used. This is the Wrst report of consistent production of antifunga l metabolites by C. minitans.

Suppression of Sclerotinia sclerotiorum by antifungal substances produced by the mycoparasite Coniothyrium minitans

“…This confirms the reports of McQuilken et al (2002McQuilken et al ( , 2003 that C. minitans produced antifungal metabolites in media including MCD. One of the antifungal metabolites produced by the European strain IMI134523 of C. minitans was identified as macrosphelide A (McQuilken et al 2003).…”

Antimicrobial activity ofConiothyrium minitansand its macrolide antibiotic macrosphelide A

“…Small‐scale liquid culture experiments were performed in 250‐ml Erlenmeyer flasks, containing 50 ml of modified Czapek‐Dox medium (MCD) (McQuilken et al. 1998, 2002, 2003).…”

Tryptophan supplementation and pH adjustment for optimizing the sporulation of Coniothyrium minitans

“…The optimum pH for sporulation of C. minitans was 4.5-6.2, which is different from that for mycelia extension (from 3.3 to 5.6) (McQuilken et al 1997(McQuilken et al , 2002Ooijkaas et al 1999). Thus, maintaining the correct pH during growth might maximize the yield of C. minitans spores.…”

“…Coniothyrium minitans CBS 148.96 (McQuilken et al 2002;Jones et al 2003), was grown on potato/dextrose/agar (PDA), pH 6, for 14 days. Conidial suspensions were made by flooding the plate with sterile 2%(w/v) glycerol.…”