Autolytic Activity and an Autolysis-Deficient Mutant of Clostridium acetobutylicum

Abstract

The optimum conditions for autolysis and autoplast formation in Clostridium acetobutylicum P262 have been defined. Autolysis was optimal at pH 6.3 in 0.04 M sodium phosphate buffer, and the bacterium produced latent and active forms of an autolytic enzyme. The ability of cells to autolyze decreased sharply when cultures entered the stationary phase. Autoplasts were induced by 0.25 to 0.5 M sucrose and were stable in media containing sucrose, CaCl2, and MgCl2. A pleiotropic autolysis-deficient mutant (lyt-1) was isolated. The mutant produced less autolysin than did the parent P262 strain, and it had an altered cell wall which was more resistant to both its own and P262 autolysins. The mutant formed long chains of cells, and lysozyme was required for the production of autoplasts. Growth of the P262 strain or the lyt-1 mutant was inhibited by the same concentrations of penicillin, ampicillin, and vancomycin. The lyt-1 mutant strain treated with the minimum growth-inhibitory concentration of penicillin autolyzed upon the addition of wild-type autolysin to the autolysis buffer at the same rate as did the untreated P262 strain. Chloramphenicol did not protect the penicillin-treated lyt-1 cells against autolysis enhanced by exogenous wild-type autolysin.

Acetone-butanol fermentation revisited.

“…This cell-free autolysin was found to be a glycoprotein with a molecular mass of 28,000 (269,279). A similar cell-bound autolysin was reported to be present in exponential-phase cells of the same strain which could be activated to produce autoplasts under the appropriate conditions in an osmotically stabilized medium (5,279).…”

“…The release of clostocin 0 was accompanied by premature cell lysis due to the degeneration of the cell wall by a newly synthesized lysin. Degenerative changes and premature lysis appear to be common features of saccharolytic solventproducing clostridia, but cell lysis may also be associated with the overproduction and release of cell-free autolysin without the involvement of phagelike particles (5,16).…”

Autolytic Activity and Butanol Tolerance of Clostridium acetobutylicum

“…Bacterial strains and media. C. acetobutylicum P262 was supplied by National Chemical Products Ltd., Germiston, South Africa, and was utilized in previous studies (1)(2)(3)8). The isolation and characterization of the autolysis-deficient lyt-l mutant has been described previously (1).…”

Gas Fermentation for Commercial Biofuels Production

“…These can be achieved by directed evolution, random mutagenesis and/or targeted genetic engineering. Traditionally, chemical mutagenesis [135][136][137] and adaption strategies [138,139] have been deployed to select for these traits. However, these strategies are limited and often come with the expense of unwanted events.…”