Rosenthal R S, Shockman G D
J Bacteriol. 1975 Oct;124(1):419-23. doi: 10.1128/jb.124.1.419-423.1975.
Protoplasts (autoplasts) of Streptococcus faecalis were produced by the action of native autolytic N-acetylmuramidase in the absence of added peptidoglycan hydrolases and were grown in osmotically stabilized medium containing L-[3H]lysine and D-[14C]alanine. To reduce the level of muralytic hydrolysis of glycan chains during growth, heat-inactivated cell walls were added to the medium to bind autolytic enzyme, and tetracycline (1 mug/ml) was added to inhibit further enzyme synthesis. Under these conditions, protoplasts synthesized newly labeled peptidoglycan in the form of soluble, infrequently peptide cross-linked glycan chains which were released into the supernatant medium. These relatively large glycan chains were not transferred to exogenously added cell walls.
粪肠球菌原生质体（自原生质体）是在未添加肽聚糖水解酶的情况下，由天然自溶N - 乙酰胞壁酸酶作用产生的，并在含有L - [³H]赖氨酸和D - [¹⁴C]丙氨酸的渗透压稳定培养基中生长。为了降低生长过程中聚糖链的溶壁水解水平，向培养基中添加热灭活细胞壁以结合自溶酶，并添加四环素（1微克/毫升）以抑制进一步的酶合成。在这些条件下，原生质体以可溶性、很少有肽交联的聚糖链形式合成新标记的肽聚糖，这些聚糖链释放到上清培养基中。这些相对较大的聚糖链没有转移到外源添加的细胞壁上。
