Abstract:Our study showed that the effect of light on germinating spores of Streptomyces was variable: some species were indifferent, whereas others, such as Streptomyces viridosporus, displayed a marked inhibition of CFU numbers on growth medium. A special study with S. viridosporus showed that light only had an impact during the first few hours of spore incubation. The effects of scavengers of toxic forms of oxygen and of photosensitizers, along with the oxidative stress of illuminated spores evidenced by the superox… Show more
“…2 B and E ). Therefore, similar to the previous discovery revealed by Imbert et al [9] , visible light has a phototoxic impact against the growth of S. coelicolor . Fig.…”
Section: Resultssupporting
confidence: 88%
“…The endogenous cellular photosensitizers can absorb the entire range of visible light, but with a maximum in the blue region; meanwhile, ROS production was found to be the highest under blue light illumination [17] , which might well explain the highest phototoxicity produced by blue light. In addition, silimar to those reported in S. viridosporus [9] , S. coelicolor was more sensitive to visible light illumination in the first several hours since plating ( Fig. S2 ), which corresponds to the early stage of germination, including germ tube emergence, vegetative mycelium growth and the first round of programmed cell death (PCD) [18] .…”
Section: Resultssupporting
confidence: 60%
“…Streptomyces is a genus of gram-positive bacteria renowned for its ability to produce a variety of antibiotics and other bioactive natural products [8] . Previous research has shown that light remarkably inhibited the spore germination of some Streptomyces species, including Streptomyces viridosporus and Streptomyces coelicolor [9] . The intracellular superoxide dismutase levels were found to be remarkably enhanced by the light under aerobic condition, indicating that light and oxygen together might produce high amounts of ROS.…”
Section: Introductionmentioning
confidence: 98%
“…Most Streptomyces produce carotenoids under light induction [10] . Although carotenoids were known to protect cells from photodynamic damage in Rhodobacter species [11] , these pigments were shown to have no protective role against the lethal effects of light in Streptomyces species [9] . And till now, little is known about how Streptomyces copes with the photo-oxidative stress.…”
It has been known that some Streptomyces species, including the model strain Streptomyces coelicolor, are vulnerable to visible light. Much evidence demonstrated that the phototoxicity induced by visible light is a consequence of the formation of intracellular reactive oxygen species (ROS), which are potentially harmful to cells. In this study, we found that α-ketoglutarate (α-KG) has a protective role against the phototoxicity in S. coelicolor. It could be because that α-KG can detoxify the ROS with the concomitant formation of succinate, which mediates the cells getting into anaerobiosis to produce more NADH and maintain intracellular redox homeostasis, a situation that was demonstrated by overexpressing gdhA in S. coelicolor. This finding, therefore, connects the central metabolites with the bacterial resistance against phototoxicity effect induced by visible light.
“…2 B and E ). Therefore, similar to the previous discovery revealed by Imbert et al [9] , visible light has a phototoxic impact against the growth of S. coelicolor . Fig.…”
Section: Resultssupporting
confidence: 88%
“…The endogenous cellular photosensitizers can absorb the entire range of visible light, but with a maximum in the blue region; meanwhile, ROS production was found to be the highest under blue light illumination [17] , which might well explain the highest phototoxicity produced by blue light. In addition, silimar to those reported in S. viridosporus [9] , S. coelicolor was more sensitive to visible light illumination in the first several hours since plating ( Fig. S2 ), which corresponds to the early stage of germination, including germ tube emergence, vegetative mycelium growth and the first round of programmed cell death (PCD) [18] .…”
Section: Resultssupporting
confidence: 60%
“…Streptomyces is a genus of gram-positive bacteria renowned for its ability to produce a variety of antibiotics and other bioactive natural products [8] . Previous research has shown that light remarkably inhibited the spore germination of some Streptomyces species, including Streptomyces viridosporus and Streptomyces coelicolor [9] . The intracellular superoxide dismutase levels were found to be remarkably enhanced by the light under aerobic condition, indicating that light and oxygen together might produce high amounts of ROS.…”
Section: Introductionmentioning
confidence: 98%
“…Most Streptomyces produce carotenoids under light induction [10] . Although carotenoids were known to protect cells from photodynamic damage in Rhodobacter species [11] , these pigments were shown to have no protective role against the lethal effects of light in Streptomyces species [9] . And till now, little is known about how Streptomyces copes with the photo-oxidative stress.…”
It has been known that some Streptomyces species, including the model strain Streptomyces coelicolor, are vulnerable to visible light. Much evidence demonstrated that the phototoxicity induced by visible light is a consequence of the formation of intracellular reactive oxygen species (ROS), which are potentially harmful to cells. In this study, we found that α-ketoglutarate (α-KG) has a protective role against the phototoxicity in S. coelicolor. It could be because that α-KG can detoxify the ROS with the concomitant formation of succinate, which mediates the cells getting into anaerobiosis to produce more NADH and maintain intracellular redox homeostasis, a situation that was demonstrated by overexpressing gdhA in S. coelicolor. This finding, therefore, connects the central metabolites with the bacterial resistance against phototoxicity effect induced by visible light.
Botrytis cinerea is an economically important disease on numerous vegetables including tomato. From our previous studies, a spore suspension of Streptomyces philanthi RL-1-178 and RM-1-138 and Streptomyces mycarofaciens SS-2-243 showed strong inhibition against B. cinerea. In this study, the efficacy of their antifungal metabolites against B. cinerea was investigated after enhancing the production through the optimum culture medium and environmental conditions (temperature, light/dark cycle). In vitro studies indicated that glucose yeast-malt (GYM) agar and incubation at 28°C were optimal for growth and mass spore production of all three Streptomyces strains. Moreover, light/dark conditions had a positive effect on the growth and spore production of S. philanthi RM-1-138 and RL-1-178 but not on S. mycarofaciens SS-2-243.Both strains of S. philanthi possessed an antifungal activity against B. cinerea (100% inhibition) while S. mycarofaciens showed different results on PDA (83% inhibition) and GYM (88% inhibition) at the optimum incubation temperature at 21°C. The antifungal compounds from S. philanthi RM-1-138 exhibited the highest protection efficacy against B. cinerea on tomato leaves (82.89% and 0.33 cm 2 lesion areas symptoms). The antifungal compounds RM-1-138, identified by GC-MS, were greatly altered based on components concentration under various temperatures and light/dark conditions. The anti-B. cinerea of S. philanthi RM-1-138 was established at a higher level in several metabolic compounds in the dark condition (11 and 32 antifungal compounds after incubation at 21°C and 28°C, respectively) than in the light condition (11 and 19 antifungal compounds after incubation at 21°C and 28°C, respectively). At 21°C, the dominant component was acetic acid (67.41% and 68.77% in light and dark conditions, respectively) while at 28°C, benzeneacetamide (43.58% in light) and propanamide (20.68% in the dark) were dominant. The results clearly demonstrated the significant influence of environmental factors on the production of antifungal metabolites of Streptomyces spp.
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