Article

Influence of agitation and aeration on growth and antibiotic production by Xenorhabdus nematophila

World Journal of Microbiology and Biotechnology (Impact Factor: 1.26). 23(2):221-227. DOI:10.1007/s11274-006-9217-2

ABSTRACT The effect of agitation and aeration on the growth and antibiotic production by Xenorhabdus nematophila YL001 grown in batch cultures were investigated. Efficiency of aeration and agitation was evaluated through the oxygen mass
transfer coefficient (K
L
a). With increase in K
L
a, the biomass and antibiotic activity increased. Activity units of antibiotic and dry cell weight were increased to 232Uml−1 and 19.58gl−1, respectively, productivity in cell and antibiotic was up more than 30% when K
L
a increased from 115.9h−1 to 185.7h−1. During the exponential growth phase, DO concentration was zero, the oxygen supply was not sufficient. So, based on process
analysis, a three-stage oxygen supply control strategy was used to improved the DO concentration above 30% by controlling
the agitation speed and aeration rate. The dry cell weight and activity units of antibiotic were further increased to 24.22gl−1 and 249Uml−1, and were improved by 24.0% and 7.0%, compared with fermentation at a constant agitation speed and a constant aeration rate
(300revmin−1, 2.5lmin−1).

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