Continuous culture of Pseudomonas fluorescens with sodium maleate as a carbon source

Abstract

Pseudomonas fluorescens (ATCC 11150) was grown in batch and continuous culture in minimal media with sodium maleate as growth-limiting sole organic carbon source. Growth was followed by turbidity and dry weight measurements. Gross composition of washed cells (relative amounts of protein, lipid, RNA, and DNA) and the distribution of amino acids in protein hydrolysates of the cells were determined for cells grown in continuous culture a t various dilution rates. Extracellular concentrations of the original carbon source and a number of metabolites were monitored by a total carbon analysis, ion exchange chromatography, and ultraviolet-visible scans of cell-free supernatants and chromatographic fractions, thereof.Substrate inhibition by maleate was a major factor in the growth kinetics of both batch and continuous cultures. Excessive maleate concentration caused instability in continuous cultures. By appropriate operation, much higher specific growth rates (0.305/hr) could ultimately be achieved in continuous culture compared to batch culture (0.174/hr). Adaptation was responsible for only part of the differences between batch and continuous cultures; the differing distribution of metabolites were also major factors.

The growth dynamics of a methanol‐utilizing bacterium L3 in a batch bioreactor

“…Fumarate, an intermediate of maleate metabolism, was found to accumulate in the extracellular phase during the batch growth of P. fluorescens on sodium maleate. 4 It was suggested that the assumption of a single rate-limiting step characterizing the overall growth of microorganisms is not a valid one in modeling the growth of this microorganism.…”

“…In the ribulose monophosphate cycle methylotrophs, formaldehyde plays an important role in distributing the flow of the methanol carbon between the respiratory and assimilatory pathway^.^,'^ The complex kinetics aggravate the problem associated with the startup and stabilization of continuous bioreactors. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] An explanation of these phenomena should provide a greater understanding of microbial systems and could lead to improved product formation through changes in process control strategy. With this ultimate objective in mind a detailed investigation of the batch growth behavior of a methanol-utilizing bacterium, L3, was undertaken.…”