selenomonas ruminantium selenomonas ruminantium selenomonas ruminantium is a species of selenomonas bacteria which are closely associated with ruminants, aiding in digestion of their food. it is predominantly observed in the rumen of these animals, and is strictly anaerobic. selenomonas ruminantium scientific classification domain: bacteria phylum: bacillota class: negativicutes order: selenomonadales family: selenomonadaceae genus: selenomonas species: s. ruminantium binomial name selenomonas ruminantium(certes 1889) wenyon 1926 (approved lists 1980) shape and classification the bacterium has a rod shaped structure. gram classification 16s rrna gene identification selenomonas ruminantium was originally placed with the gram-positive firmicutes phylum based on its 16s rrna gene. it was believed to be correct until the flagellar basal test was performed. flagellar basal test the observation of flagella under electron microscope revealed the presence of four rings, a typical sign of gram negative species. observation of the flagellar basal structure confirms that s. ruminantium has an outer membrane, a characteristic of gram-negative bacteria . gram-positive outer membranes or mycomembranes were recently reported for the gram-positive general corynebacterium and mycobacterium, but none of them have flagella. tuft flagella the tuft of flagella is seen arising from the concave of basal body of s.ruminantium. the movement is achieved by self rotation about the axis of the body by the rotational force exerted by the tuft at the centre. if the polar region to midpoint distance is considered as 50% the tuft is located at the midpoint represented as 50% of the organism. lateral flagella the bacteria also exhibits polar or lateral flagellar structures depending upon the medium in which they are developed. polymorphism in flagellar structures their flagella exhibits polymorphic properties depending upon the environment of the bacteria. generally the flagellae protruding from all points are clustered around the midpoint. flagellin is glycosylated. ph effect on the structure of flagella the bacterial flagella's existence depends upon the ph. the rumen ph is about 5.5 to 7. ph effect ph range flagella 0-3 disappears 3-5 right handed coiled form 5-8 large curly coiled form 8-14 normal mobility glucose effect the medium of development determines the motility of the bacteria. for selenomonas ruminantium, glucose suppresses the flagellation. medium of development medium motility tyl motile tyg immotile tyl+glucose supplement immotile tyg+lactose supplement immotile swimming the microbe swims by self rotation about the axis of the body unlike its nearest appropriate comparison rhodobacter sphaeroides, which the microbe rotates in a direction perpendicular to the axis of the body. the average number of flagella per 20 cells is 6.the microbe swims with a speed of 16ɥm/s. hooks the shape and size of the hooks on the flagellae differ by the physiological conditions present, but the general structure is s shaped.