DYNAMICS IN OXYGEN-INDUCED CHANGES IN S-LAYER PROTEIN-SYNTHESIS FROM BACILLUS-STEAROTHERMOPHILUS PV72 AND THE S-LAYER-DEFICIENT VARIANT T5 IN CONTINUOUS-CULTURE AND STUDIES OF THE CELL-WALL COMPOSITION

Stable synthesis of the hexagonally ordered (p6) S-layer protein from the wild-type strain of Bacillus stearothermophilus PV72 could be achi eved in continuous culture on complex medium only under oxygen-limited conditions when glucose was used as the sole carbon source. Depending on the adaptation of the wild-type strain to low oxygen supply, the d ynamics in oxygen-induced changes in S-layer protein synthesis was dif ferent when the rate of aeration was increased to a level that allowed dissimilation of amino acids, If oxygen supply was increased at the b eginning of continuous culture, synthesis of the p6 S-layer protein fr om the wild-type strain (encoded by the sbsA gene) was immediately sto pped and replaced by that of a new type of S-layer protein (encoded by the sbsB gene) which assembled into an oblique (p2) lattice. In cells adapted to prolonged low oxygen supply, first, low-level p2 S-layer p rotein synthesis and second, synchronous synthesis of comparable amoun ts of both types of S-layer proteins could be induced by stepwise incr easing the rate of aeration. The time course of changes in S-layer pro tein synthesis was followed up by immunogold labelling of whole cells. Synthesis of the p2 S-layer protein could also be induced in the p6-d eficient variant T5. Hybridization data obtained by applying the radio labelled N-terminal and C-terminal sbsA fragments and the N-terminal s bsB fragment to the genomic DNA of all the three organisms indicated t hat changes in S-layer protein synthesis were accompanied by chromosom al rearrangement. Chemical analysis of peptidoglycan-containing saccul i and extraction and recrystallization experiments revealed that at le ast for the wild-type strain, a cell wall polymer consisting of N-acet ylglucosamine and glucose is responsible for binding of the p6 S-layer protein to the rigid cell wall layer.