Colletotrichum coccodes is being developed as a bioherbicide to control velvetleaf. An effective and economic process for mass production of C. coccodes sports is required for its possible development as a bioherbicide. A modified Richard's solution containing V-8 juice has been used to produce C. coccodes spores in shake flasks. However, V-8 juice is not available as a bulk commodity and is too expensive for commercial production of a bioherbicide. Soy protein and casamino acids were equal to and can replace V-8 juice for sporulation of C. coccodes . Using the Plackett-Burman experimental design, the effect of the various components in a complex medium on both the sporulation and mycelial biomass of C. coccodes were determined. Carbon concentration and carbon to nitrogen ratio as well as their interaction are critical for C. coccodes growth and sporulation. In medium containing 10 g/l carbon with C:N ratios from 10:1 to 15:1, 8 x 107 C. coccodes spores per ml were produced. Germination of the spores was 90% and they caused extensive shoot dry weight reduction of inoculated velvetleaf. C:N ratios from 10:1 to 15:1 am optimal for C. coccodes sporulation. A cyclone column bioreactor was used to investigate the effects of environmental conditions on spore yield. C. coccodes sporulation was superior with low aeration (∼0.5vvm) and low pH (4.5--5.0) compared with high aeration (2 vvm) and high pH (6.5--7.5). The optimum temperature for sporulation was 24°C. C. coccodes sporulation commences when the dissolved oxygen supply becomes restricted. Spore yields of over 3.5 x 107 spores per ml can be obtained within four days from batch culture. Scale up to a 100 liter cyclone column bioreactor yielded 2.5 x 107 C. coccodes spores per ml within four days.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35422 |
| Date | January 1997 |
| Creators | Yu, Xuefeng. |
| Contributors | Watson, Alan K. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Plant Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001615546, proquestno: NQ44638, Theses scanned by UMI/ProQuest. |
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