Growth requirements for production of stable cells of the bioherbicidal bacterium Xanthomonas campestris |
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Authors: | M A Jackson J S Frymier B J Wilkinson P Zorner S Evans |
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Institution: | (1) Fermentation Biochemistry Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL 61604, USA, US;(2) Illinois State University, Department of Biological Sciences, Normal, IL 61790–4120, USA, US;(3) Mycogen Corporation, San Diego, CA, USA, US |
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Abstract: | Xanthomonas campestris MB245, a specific pathogen of the weedy grass Poa annua (annual bluegrass), is being developed as a bioherbicide to control this pest in turf. Nutritional and environmental factors
were evaluated based on their ability to support rapid submerged culture growth and high cell yield. Temperature optima for
the growth of X. campestris cells in submerged culture were between 27 and 30°C. At 30°C, optimal nutritional conditions for X. campestris growth supported generation times of 150–175 min and cell yields after 24 h growth of 1–2 × 1010 cells ml−1. Media containing sucrose or glucose as the carbon source and various organic nitrogen sources supported optimal X. campestris growth and cell yield. The addition of vitamin mixtures to complex and defined media had no significant effect on growth
or cell yield. The age of X. campestris cultures had a significant impact on cell survival after freeze drying. Following freeze drying, log phase cell survival
(44%) was significantly lower than early and late stationary phase cell survival, 62% and 68%, respectively. Cells harvested
in stationary phase, freeze dried and stored under vacuum at 4°C, showed no significant loss in viability after 6 months.
Thus, high cell concentrations of the bioherbicide X. campestris can be rapidly produced in submerged culture and stabilized as freeze-dried preparations.
Received 14 August 1998/ Accepted in revised form 8 October 1998 |
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Keywords: | : bacterial bioherbicide freeze drying growth phase liquid culture production shelf life biological control |
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