Which of the following organisms is known to be non-spore forming?

Corynebacterium diphtheriae is recognized as a non-spore-forming organism. This bacterium is responsible for diphtheria, a serious respiratory illness. Unlike the other listed organisms, which are part of genera that typically form spores as a means of survival under unfavorable environmental conditions, Corynebacterium diphtheriae does not produce spores. Instead, it reproduces by binary fission and can be found in form of club-shaped rods or as pleomorphic bacilli, which contribute to its identification in laboratory diagnostics.

In contrast, Bacillus cereus, Bacillus anthracis, and Clostridium perfringens are all known for their ability to form spores. Bacillus species are aerobic or facultatively anaerobic and produce durable spores that can withstand extreme conditions. Clostridium species, being anaerobic, also form spores that allow them to survive in oxygen-deprived environments. The non-spore-forming characteristic of Corynebacterium diphtheriae distinguishes it significantly from these other genera. Understanding these differences is important in microbiology, especially regarding the pathogenic potential and survival strategies of various bacteria.