Hydrodynamic effects on microcapillary motility and chemotaxis assays of Methylosinus trichosporium OB3b

The Palleroni microcapillary assay was evaluated with regard to the chemotactic behavior of Methylosinus trichosporium OB3b, an obligate methanotroph which degrades a number of chlorinated hydrocarbons. The results showed that the Palleroni microcapillary assay is subject to abiotic hydrodynamic effects arising from a density-induced convection. The source of this convection was most probably the fluid density difference between thee cell suspension and the microcapillary buffer. This procedure is more useful when evaluating the behavior of highly motile strains of bacteria.