Growth phase-dependent expression of an endoglucanase encoding gene () in A2

Abstract

Different growth phases of Streptomyces rochei A2, a cellulolytic strain isolated from termite gut, were determined in liquid culture. The strain exhibited a multiphasic growth curve typical of streptomycetes. In S. rochei A2, the secreted endoglucanase EglS is coded by a TTA-containing gene, conserved in other Streptomyces. The onset of S. rochei A2 eglS gene expression was determined by RT-PCR using total RNA extracted at different growth phases. The eglS gene was expressed only during transition, second rapid growth and stationary phases, the timing of expression being transcriptionally regulated.

Cellulolytic enzymes in <i>Microbulbifer</i> sp. Strain GL-2, a marine fish intestinal bacterium, with emphasis on endo-1,4-β-glucanases Cel5A and Cel8

“…Bacteria enter a stationary phase of growth when the nutrient supply becomes restricted (Kolter et al, 1993); we infer that GL-2 expresses cellulases under the nutrient-deprived conditions of stationary phase, such that these enzymes do not contribute directly to earlier growth phases. A similar pattern has been observed in Streptomyces rochei A2, a strain isolated from the termite gut, in which transcription of the gene encoding EglS (a secreted endoglucanase) does not occur during the logarithmic growth phase; instead, the highest eglS transcript levels were observed during stationary phase (Tamburini et al, 2004), consistent with the case in GL-2. On the other hand, a recent report regarding a marine Microbulbifer isolate indicated that the levels of cellulases increase during the mid-logarithmic growth phase, whereas higher levels of alginate lyase activity are observed in stationary phase (Li et al, 2022).…”