Isolation of L Forms from Group A Streptococci Exposed to Bacitracin

Abstract

Isolation of L forms from group A streptococci exposed to bacitracin. J. Bacteriol. 89:1581-1585. 1965.-L forms were obtained from group A streptococci by exposure to bacitracin on gradient plates, although novobiocin was ineffective in this respect. Subcultures of these L forms had morphological and bacteriological properties similar to those obtained with penicillin. M protein was detected in L-form colony smears by immunofluorescent staining with type-specific conjugate. The L forms were not stained with group-specific conjugate. Parallel precipitin tests performed with extracts from a heavy growth of L forms on agar confirmed these findings. Thus, the L forms obtained with bacitracin continue to produce M protein but are devoid of the group-specific carbohydrate which is a major component of cell-wall structure.

M proteins of group A streptococci.

“…Several experiments tend to support this functional arrangement. For example, protoplasts and L-forms of group A streptococci synthesize M protein and deposit it into the surrounding medium (57,83,139), and membranes from osmotically lysed protoplasts contain small amounts of M protein which has been detected by immunofluorescent techniques (41). Treating whole streptococci with trypsin for short periods digests away the superficial layer containing the M protein, leaving viable cells which, in limiting nutrient media containing penicillin to inhibit cell division, are capable of resynthesizing M protein within 60 min (39,46).…”

Recovery of Airborne Streptococcal L-Forms at Various Relative Humidities

“…Detailed structural elements, observed when L-forms are prepared by the direct agar-fixation technique (1), also remained unaltered. In view of the lack of the group-specific carbohydrate which is a major component of the streptococcal cell wall (10,11) and by virtue of their inability to revert, the stable streptococcal L-forms used did not lend themselves to serological identification. They did, however, consistently produce f.-hemolysis on supportive agar medium which contained 5%7…”