Induction, growth and antibiotic production of Streptomyces viridifaciens L-form bacteria

Abstract

Aims: To induce, cultivate and investigate the characteristics of L-form bacteria derived from the ®lamentous actinomycete Streptomyces viridifaciens. Methods and Results: L-forms were induced in a liquid medium supplemented with lysozyme and penicillin. A stable culture which no longer required inducing agents but could still revert, was obtained by the twelfth subculture. The speci®c growth rate of stable L-forms was faster (0á751) than unstable L-forms (0á361). After the exponential growth phase, the cell diameter continued to increase, as did the percentage of vacuoles. Morphologically, the Lforms appeared as spherical bodies with no signs of differentiation and were sensitive to osmotic stress, indicating removal of the cell wall. The L-forms produced secondary metabolites although much lower levels of antibiotic were assayed in the L-forms compared with the cell walled forms. Conclusions: Stable L-form bacteria were induced from S. viridifaciens and their growth characterized. The L-forms produced secondary metabolites. Signi®cance and Impact of the Study: Stable Streptomyces L-forms were induced and have potential as biocontrol agents.

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

“…In vivo , too, the mixture of both antagonists inhibited the pathogen to the same degree as freshly prepared inocula did. The results agree with those of other authors (Ongena et al., 2000; Innes and Allan, 2001; Clarkson et al., 2004; De la Fuente et al., 2004; McLean et al., 2005) who studied the colonizing capacity of strains of Pseudomonas , Streptomyces and/or Trichoderma in soils and roots for biocontrol experiments against different pathogens.…”

Morphogenesis of Streptomyces in Submerged Cultures

“…Production of secondary metabolites, such as antibiotics or antitumor agents, is often linked to the inherent capacity to form mycelial pellets. Subsequent cultivations in osmotically balanced media can lead to the acquisition of mutations that allow these cells to propagate without their cell wall, even in the absence of the inducing agents (i.e., penicillin and lysozyme; Innes & Allan, 2001;Leaver, Dominguez-Cuevas, Coxhead, Daniel, & Errington, 2009;Mercier, Kawai, & Errington, 2013;Errington, 2013). Treatment of mycelia with lysozyme results in the formation of protoplasts, which are identical-sized spherical cells without a cell wall used for cell fusion and plasmid transformation (Bibb, Ward, & Hopwood, 1978;Hopwood, Wright, Bibb, & Cohen, 1977).…”

“…However, streptomycetes can also be forced to produce single cells. L-forms have been shown to associate with plants acting as biocontrol agents (Amijee, Allans, Waterhouse, Glover, & Paton, 1992;Innes & Allan, 2001). While protoplasts cannot propagate, streptomycetes can also form so-called L-forms (Innes & Allan, 2001).…”

“…L-forms have been generated in a wide range of unrelated bacterial species, including, among others, Escherichia coli (Glover, Yang, & Zhang, 2009), B. subtilis (Leaver et al, 2009), and Listeria monocytogenes (Dell'Era et al, 2009), and also in several Streptomyces species, including Streptomyces hygroscopicus, S. griseus, Streptomyces levoris, and Streptomyces viridifaciens (Gumpert, 1982(Gumpert, , 1983Innes & Allan, 2001; Fig. 1.1).…”

Stress-induced formation of cell wall-deficient cells in filamentous actinomycetes

“…While the cell wall is considered an essential component of virtually all bacteria, most species can be manipulated under laboratory conditions to produce so-called L-forms that are able to propagate without their wall 14–17 Typically, L-forms are generated by exposing walled bacteria to high levels of lysozyme combined with antibiotics that target cell wall synthesis in media containing high levels of osmolytes 18, 19 Stable L-forms that can propagate indefinitely without the cell wall require two mutations that fall in separate classes 18 . The first class of mutations leads to an increase in membrane synthesis, either directly by increasing fatty acid biosynthesis, or indirectly by reducing cell wall synthesis 20 .…”