A molecular key for building hyphae aggregates: the role of the newly identified Streptomyces protein HyaS.
Bottom Line: The HyaS protein is dominantly associated with the substrate hyphae.Investigations of ΔH transformants, each carrying a specifically mutated gene, lead to the conclusion that the in situ oxidase activity correlates with the pellet-inducing role of HyaS, and depends on the presence of certain histidine residues.These data present the first molecular basis for future manipulation of pellets, and concomitant production of secondary metabolites during biotechnological processes.
Affiliation: University of Osnabrück, FB Biology/Chemistry, Applied Genetics of Microorganisms, 49069 Osnabrück, Germany.Show MeSH
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Mentions: As turbidity measurements are not conclusive to investigate cultures of Streptomyces mycelia, pre‐cultivated strains were transferred to optimized shaking conditions (145 r.p.m.), and the flasks were inspected microscopically. After 20 h, the substrate hyphae of ΔHpHY11, ΔHpHY12 and ΔHpHY13 (Fig. 8B–D) formed more fused pellets compared with those the control ΔHpWHM3 strain (Fig. 8A). Pellets of ΔHpHY12 and ΔHpHY13 were more roundish. The pigmentation of all strains appeared similar. After further 40 h of cultivation, the pellets of ΔHpHY13 (Fig. 8H) were the most irregular as to shape and size, and they had more fused packages than those of ΔHpHY11 (Fig. 8F). Pellets of ΔHpHY12 (Fig. 8G) had the smallest diameter, and they comprised roundish and elongated ones. In addition, they had fewer fusion sites than those of ΔHpHY11. The aggregates of the control strain ΔHpWHM3 (Fig. 8E) had larger diameters than those of ΔHpHY11 and ΔHpHY12 and lacked close contact sites. The degree of pigmentation appeared most pronounced for ΔHpHY11 and ΔHpHY13. Following prolonged cultivation (120 h) the pellets of ΔHpHY12 (Fig. 8K) and ΔHpWHM3 (Fig. 8I) were transparent, and their diameter diminished compared with 40 h. In addition, a pronounced cloudy‐like background was present; this was due to masses of individual hyphae and small mycelia (Fig. 8I and K). The pellet clumps of ΔHpHY13 (Fig. 8L) were more compact, and patches within them were more coloured compared with those of ΔHpHY11 (Fig. 8J). These features correlated with fewer individual hyphae and small mycelia. Taken together, the pellets of ΔHpHY13 were even more stable than those ΔHpHY11.
Affiliation: University of Osnabrück, FB Biology/Chemistry, Applied Genetics of Microorganisms, 49069 Osnabrück, Germany.