Synergistic algicidal effect and mechanism of two diketopiperazines produced by Chryseobacterium sp. strain GLY-1106 on the harmful bloom-forming Microcystis aeruginosa

Abstract

A potent algicidal bacterium isolated from Lake Taihu, Chryseobacterium sp. strain GLY-1106, produces two algicidal compounds: 1106-A (cyclo(4-OH-Pro-Leu)) and 1106-B (cyclo(Pro-Leu)). Both diketopiperazines showed strong algicidal activities against Microcystis aeruginosa, the dominant bloom-forming cyanobacterium in Lake Taihu. Interestingly, these two algicidal compounds functioned synergistically. Compared with individual treatment, combined treatment with cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) significantly enhanced algicidal activity, accelerated the increase in intracellular reactive oxygen species (ROS) levels in M. aeruginosa, and further decreased the activities of antioxidases, effective quantum yield and maximal electron transport rate of M. aeruginosa. The results also showed that the algicidal characteristics of cyclo(4-OH-Pro-Leu) are distinct from those of cyclo(Pro-Leu). Cyclo(4-OH-Pro-Leu) mainly interrupted the flux of electron transport in the cyanobacterial photosynthetic system, whereas cyclo(Pro-Leu) mainly inhibited the activity of cyanobacterial intracellular antioxidases. A possible algicidal mechanism for the synergism between cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) is proposed, which is in accordance with their distinct algicidal characteristics in individual and combined treatment. These findings suggest that synergism between algicidal compounds might be used as an effective strategy for the future control of Microcystis blooms.

Identification and Evaluation of Antibacterial Compounds from the Vibrio sp. associated with the Ascidian Pycnoclavella diminuta

“…The EI-MS spectrum of SFr 2 indicated ions at 70 (M-C 7 H 10 NO 2 ) and 154 (M-C 4 H 8 ) (Fig 3). The fragmentation pattern of the spectrum has similarities to the EI-MS spectrum obtained in the previous study by Guo et al (2015).…”

The algicidal activity of Aeromonas sp. strain GLY‐2107 against bloom‐forming Microcystis aeruginosa is regulated by N‐acyl homoserine lactone‐mediated quorum sensing

“…aeruginosa , whereas cyclo(Pro‐Leu) mainly inhibits the activity of intracellular antioxidases of M . aeruginosa (Guo et al ., ). The EC 50 values (concentration for 50% maximal effect) of cyclo(Pro‐Gly), cyclo(Pro‐Val), cyclo(Pro‐Leu) and cyclo(4‐OH‐Pro‐Leu) against M .…”

“…Lzh‐2, showed algicidal activity. Cyclo(Gly‐Phe) belongs to the diketopiperazine family, which contains a large group of small molecules produced by a wide range of microbes that exhibit many valuable biological properties (Ortiz‐Castro et al ., ), including antibacterial (Fdhila et al ., ), algicidal (Li et al ., ; Guo et al ., ; Li et al ., ; Lin et al ., ) and signal (sexual pheromone) (Gillard et al ., ) activities. During the sexual reproduction of the diatom Seminavis robusta , diproline (proline‐derived diketopiperazine) acting as the sexual pheromone of the attracting mating type (MT − cells) can induce the migratory behavior of the migrating mating type (MT + cells) (Gillard et al ., ).…”

“…() found cyclo(Phe‐Ala) and cyclo(Ala‐Trp) isolated from marine bacterium Pseudomonas putida showed the anti‐diatom activities. Although cyclo(Gly‐Phe) was first identified to have algicidal activity against M. aeruginosa , some other diketopiperazine substances produced by other algicidal bacteria have been found to have algicidal activities against M. aeruginosa , such as: cyclo(Pro‐Gly) (Li et al ., ; Li et al ., ; Lin et al ., ), cyclo(Pro‐Val) (Li et al ., ), cyclo(Pro‐Leu) (Guo et al ., ) and cyclo(4‐OH‐Pro‐Leu) (Guo et al ., ). Cyclo(Pro‐Gly) and cyclo(Pro‐Val) can induce morphological changes and loss of cell integrity of M .…”

Algicidal Activity of Bacillamide Alkaloids and Their Analogues against Marine and Freshwater Harmful Algae

“…As a result, much interest has been focused on the use of bacteria for controlling blooms of harmful algae in marine and freshwater environments. Some of the related algicidal chemicals have been isolated and identified from these bacteria [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Amongst them, bacillamide alkaloids, produced by marine Bacillus sp.…”