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Unlabelled: Copper sulfate (CuSO4) has been widely used as an algicide to control harmful cyanobacterial blooms (CyanoHABs) in freshwater lakes. However, there are increasing concerns about this application, due mainly to the general toxicity of CuSO4 to other aquatic species and its long-term persistence in the environment. This study reported the isolation and characterization of two natural algicidal compounds, i.e., tryptamine and tryptoline, from Streptomyces eurocidicus JXJ-0089. At a concentration of 5 μg/ml, both compounds showed higher algicidal efficiencies than CuSO4 on Microcystis sp. FACHB-905 and some other harmful cyanobacterial strains. Tryptamine and tryptoline treatments induced a degradation of chlorophyll and cell walls of cyanobacteria. These two compounds also significantly increased the intracellular oxidant content, i.e., superoxide anion radical (O2 (-)) and malondialdehyde (MDA), but reduced the activity of intracellular reductants, i.e., superoxide dismutase (SOD), of cyanobacteria. Moreover, tryptamine and tryptoline treatments significantly altered the internal and external contents of microcystin-LR (MC-LR), a common cyanotoxin. Like CuSO4, tryptamine and tryptoline led to releases of intracellular MC-LR from Microcystis, but with lower rates than CuSO4 Tryptamine and tryptoline (5 μg/ml) in cyanobacterial cultures were completely degraded within 8 days, while CuSO4 persisted for months. Overall, our results suggest that tryptamine and tryptoline could potentially serve as more efficient and environmentally friendly alternative algicides than CuSO4 in controlling harmful cyanobacterial blooms., Importance: Cyanobacterial harmful algal blooms (CyanoHABs) in aquatic environments have become a worldwide problem. Numerous efforts have been made to seek means to prevent, control, and mitigate CyanoHABs. Copper sulfate (CuSO4), was once a common algicide to treat and control CyanoHABs. However, its application has become limited due to concerns about its general toxicity to other aquatic species and its long-term persistence in the environment. There is a great need for algicides with higher specificity and low environmental impacts. This study reports the isolation and characterization of two natural algicidal compounds from a streptomycete strain, Streptomyces eurocidicus JXJ-0089. Our results suggest that the identified algicides could potentially serve as more efficient and environmentally friendly alternative algicides than CuSO4 in controlling harmful cyanobacterial blooms., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

An antialgal compound was isolated from the cultured broth of Streptomyces jiujiangensis JXJ 0074(T) by using bioassay methods. Based on the data of (1)H-NMR, (13)C-NMR, ESI-MS, and thin layer chromatography, the active compound was identified as L-valine, which showed antialgal activity mainly against Microcystis. L-valine exhibited greater antialgal activities than both L-lysine and copper sulfate (CuSO4) did on Microcystis aeruginosa lawn. However, M. aeruginosa recovered growth earlier with higher growth rate in L-valine treatment than in L-lysine treatment. L-valine dissipated completely within 2 days, much quicker than L-lysine (6 days), which resulted in the lysing of more than 80 % M. aeruginosa cells and the release of amount of intracellular microcystin-LR (MC-LR) within 2 days. As a resultant, the extracellular MC-LR content was more than twice of the control from day 1 to 5. Exposure to L-valine significantly promoted the synthesis of MC-LR. L-lysine also promoted the release and synthesis of MC-LR with much lesser efficiency than L-valine. L-valine could damage Microcystis severely, causing perforation and collapse of M. aeruginosa cells and decrease of the chlorophyll. The superoxide dismutase (SOD) activity in L-valine-treated cells of M. aeruginosa initially increased with 32.94 ± 3.37 % higher than the control after 36 h and then decreased quickly. However, the increase rate of superoxide anion radical (O2 (-)) was much higher than that of SOD, which resulted in serious lipid peroxidation and accumulation of malondialdehyde (MDA). To our knowledge, this is the first report showing L-valine active against cyanobacteria.

Previous investigations suggested that Streptomyces jiujiangensis JXJ 0074(T) can secrete antialgal compounds. In this study, an antialgal compound was isolated from the cultured broth of S. jiujiangensis JXJ 0074(T) by using bioassay methods. Based on spectroscopic data, the active compound was identified as 2'-deoxyadenosine, which exhibited a greater antialgal activity against cyanobacteria than its analogues such as adenosine, guanosine, and 2'-deoxyguanosine. The antialgal activity of 2'-deoxyadenosine increased with the content and time. 2'-Deoxyadenosine severely damaged the vegetative cells of cyanobacteria, causing crumpling, collapse, expanding, perforation, breakage of filamentous cyanobacteria, and decrease of the chlorophyll. However, 2'-deoxyadenosine seemed to have less impact on the morphology of heterocysts of filamentous cyanobacteria. The superoxide dismutase (SOD) activity in the treated cells of M. aeruginosa FACHB-905 initially increased with 31.14 ± 2.00% higher than that of the control after 36 h and then decreased quickly. On the same time, there were rapid increases in superoxide anion radical (O2 (-)) and malondialdehyde (MDA) contents with 315.53 ± 12.81 and 84.72 ± 6.15% higher than these of the controls at 60 h, respectively. The intracellular microcystin-LR (MC-LR) content in the treated cells of M. aeruginosa FACHB-905 increased by 36.34 ± 7.35% 1 day later, followed by a rapid decrease with a rate of 90.50 ± 1.08% 8 days later, while the extracellular MC-LR content showed no significant difference with the control. Five days after adding 15 μg/ml of 2'-deoxyadenosine to the culture of M. aeruginosa FACHB-905, there was no 2'-deoxyadenosine detected by HPLC, suggesting that 2'-deoxyadenosine completely degraded. This study provides a new clue to screen natural-based antialgal compounds from nucleoside analogues.

Strain JXJ 0135(T), an anti-cyanobacterial actinomycete, was isolated from a soil sample collected from Lushan Mountain, south China, and identified by using polyphasic approach. Phylogenetic analysis of the near-complete 16S rRNA gene sequence indicated that strain JXJ 0135(T) belongs to the genus Streptomyces and exhibited distinct subclade and also highest similarity (98.6%) to Streptomyces scopuliridis RB72(T). The strain developed well-branched substrate and aerial mycelia, and produced spiral spore chains. Spores were elliptical and the spore surface was smooth. The strain contained LL-diaminopimelic acid with whole-cell sugars of mannose, rhamnose, glucose and galactose. Phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannosides, phosphotidylinositol dimannoside, an unidentified aminophospholipid and an unknown phospholipid. The menaquinones were MK-9(H6) and MK-9(H8). The major components of the fatty acids were anteiso-C15:0, iso-C16:0, anteiso-C17:0, iso-C15:0, C16:0, iso-C17:0 and iso-C14:0. The G+C content was 69.3 mol%. The DNA-DNA hybridization value between JXJ 0135(T) and S. scopuliridis RB72(T) was 41.2±1.4%. On the basis of the polyphasic data, strain JXJ 0135(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces lushanensis sp. nov. is proposed. The type strain is JXJ 0135(T) (=DSM 42121(T)=JCM 19628(T)=KCTC 29261(T)=KACC 17834(T)=NRRL B-24994(T)).

An actinomycete capable of lysing cyanobacteria, strain JXJ 0074(T), was isolated from a soil sample collected from Jiangxi province, south China, and characterized by using polyphasic taxonomy. The new isolate showed morphological and chemotaxonomic properties typical of members of the genus Streptomyces. Phylogenetic analysis of the near-complete 16S rRNA gene sequence indicated that strain JXJ 0074(T) should be affiliated to the genus Streptomyces and exhibited highest similarities to Streptomyces shenzhenensis DSM 42034(T) (98.99 %) and Streptomyces lucensis NBRC 13056(T) (98.60 %), while the similarities to other members of the genus are lower than 98.22 % similarity. However, the DNA-DNA hybridization values between strain JXJ 0074(T) and S. shenzhenensis DSM 42034(T) or S. lucensis NBRC 13056(T) were 46.2 ± 2.6 and 32.6 ± 3.1 %, respectively. Thus, on the basis of the polyphasic data, strain JXJ 0074(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces jiujiangensis sp. nov. is proposed. The type strain is JXJ 0074(T) (= BCRC 16953(T) = KCTC 29262(T)).