CORYNEFORM BACTERIA
CORYNEFORM BACTERIA
Coryneform bacteria are a group of Gram-positive, non-sporulating, and predominantly aerobic and nonmotile
organisms with the defining characteristic of being pleomorphic rods. Different species have a wide range of cell morphologies - cells may be club-shaped, change shape during development or take other irregular forms. There is an overlap in many of these species, and cells may also look different under different conditions.
Perhaps the most common of these morphologies is the rather unusual V-shaped cell arrangement, which is the result of snapping division during normal growth, (1). All bacterial cell walls consist of two layers, but during snapping division only the inner layer divides, forming a septum between the two daughter cells, which remain attached by the outer layer, (1). Due to pressure from the growing cells, this layer ruptures on one side - a swift action which causes a bend in the cell junction, (2).
THE DIFFERENT TAXA
All members of the group belong to the order Actinomycetales, but are scattered across several different families and genera. These include genera such as Corynebacterium, Microbacterium, Cellulomonas, Arthrobacter and Brevibacterium. The three this website will focus on are Corynebacterium, Arthrobacter and Cellulomonas. All species in each of these genera can be said to be coryneform.
A classification tree for coryneform bacteria
ARTHROBACTER
Arthrobacter are one of the most common soil bacteria. They're very versatile, however,
and can metabolise many different molecules, in order to survive in a wide array of habitats, (7). Their cell morphology is known to change as a stress response in certain conditions, and some species are facultatively anaerobic to survive variation in oxygen levels.
CELLULOMONAS
Cellulomonas are mainly found in soil or in the rumen of various animals, with which they have a symbiotic relationship. This is due to their ability to break down cellulose. The genus is represented by a wide range of cell morphologies, and different species can have many different shapes.
GENERAL ECOLOGY
The coryneform group is ubiquitous, and although species of most genera can be found in soil, many also live in water, plants, animals, air, and many more unusual environments. Members of the group are able to make use of many different molecules as a carbon, nitrogen, or energy source. Some species are unusually resilient, growing in ever-changing environments, and many change themselves in order to do so. This includes shape changes, aerobic to anaerobic respiration, fermentative metabolism and many other mechanisms. Overall, coryneforms can be said to be classified by their sheer diversity.
OVERVIEW OF THE CORYNEFORMS
Coryneform Bacteria - An Overview
