Cupriavidus metallidurans CH34 has long been known for its temperature-induced mutagenesis and mortality phenotype (TIMM), for which a genetic origin has been suggested repeatedly. In this report, we present microscopic-based evidences that the TIMM process actually starts with a septation defect, leading to aberrant cell morphologies. Moreover, the septation defect of CH34 could be induced by NaOCl, thus showing that the TIMM phenotype may be part of a more general stress response. Sequence analysis of a TIMM survivor exhibiting a recurrent recognizable lysA mutation ruled out the possibility of a genetic ground linking TIMM survival and peptidoglycan synthesis.