The efficacy and mechanisms of fungal suppression of freshwater harmful algal bloom species
ABSTRACT Microorganisms have attracted worldwide attention as possible agents for inhibiting water blooms. Algae are usually indirectly inhibited and degraded by secretion from microorganisms. In this study, algal cultures Microcystis aeruginosa (Ma) FACH-918, Microcystis flos-aquae (Mf) FACH-1028, Oocystis borgei (Ob) FACH-1108, and M. aeruginosa PCC 7806 were co-cultured with the fungus strain Trichaptum abietinum 1302BG. All algal cells were destroyed within 48 hours (h) of co-incubation. Scanning electron microscope and transmission electron microscope observation revealed that the fungal strain had preying ability on the algal cells. The mechanism may be that the algal cells were encased with a mucous membrane secreted by the fungal mycelia, and finally degraded by the fungus directly.
- SourceAvailable from: Tianling Zheng
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- "Plants (Yan et al., 2012), protozoa (Tillmann, 2004), microalgae (Yamasaki et al., 2010) and microorganism (Luo et al., 2013; Mayali and Azam, 2004; Zheng et al., 2013), have been reported to exert inhibitory effects on the growth of HABs. Among these, microorganisms (Zhang et al., 2013) were considered to provide better HAB control, especially the algicidal bacteria (Jia et al., 2010; Nakano et al., 2003; Su et al., 2011; Wang et al., 2010). A great deal of research has focused on the interactions between algicidal bacteria and algae, suggesting that algae-lysing bacteria play an important role in regulating the growth of algal cells and have the potential to mitigate or eradicate the frequent outbreaks of HABs (Cole, 1982; Grossart and Simon, 2007). "
ABSTRACT: While searching for effective bio-agents to control harmful algal blooms (HABs), the bacterial strain LP-10, which has strong algicidal activity against Phaeocystis globosa (Prymnesiophyceae), was isolated from surface seawater samples taken from the East China Sea. 16S rDNA sequence analysis and morphological characteristics revealed the strain LP-10 belonged to the genus Bacillus. The lytic effect of Bacillus sp. LP-10 against P. globosa was both concentration- and time-dependent. Algicidal activities of different growth stages of the bacterial culture varied significantly. The lytic effect of different parts of the bacterial cultures indicated that the algal cells were lysed by algicidal active compounds in the cell-free filtrate. Analysis of the properties of the active compounds showed that they had a molecular weight of less than 1000 Da and that the active compounds were stable between -80 and 121 degrees C. The algicidal range assay indicated that five other algal species were also suppressed by strain LP-10, including: Alexandrium catenella, A. tamarense, A. minutum, Prorocentrum micans and Asterionella japonica. Our results suggested that the algicidal bacterium Bacillus sp. LP-10 could be a potential bio-agent to control the blooms of harmful algal species.Biological Control 09/2014; 76. DOI:10.1016/j.biocontrol.2014.05.007 · 1.64 Impact Factor
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- "It is generally recognized that antialgal agents produced by bacteria such as proteins, peptides amino acids, antibiotics and pigments are a promising and environment-friendly way to control HABs    , and the action mode of antialgal bacteria is speculated through direct or indirect interactions . Moreover, antialgal bacteria may play an important role in regulating harmful algal biomass in natural aquatic environments . Although antialgal bacteria studies on cyanobacteria degradation from laboratory systems to outdoor mesocosm tests can provide useful information on the relationship between microorganisms and pollutants  , they do not accurately reflect the biodegradation mechanism of HABs. "
ABSTRACT: Eutrophication has occurred frequently in various lakes and reservoirs, and the metabolic excretion produced during the algae growth causes serious water pollution and threatens ecological security. Biological control approaches such as screening bacteria with the capability to degrade cyanobacteria are an environment-friendly way. An isolated antialgal strain Streptomyces sp. KY-34, was applied to degrade the cyanobacterium Microcystis aeruginosa, and the possible biodegradation mechanism was investigated. The results showed that the fermentation liquor of Streptomyces sp. KY-34 could inhibit the growth of M. aeruginosa by restrained the synthesis of chlorophyll and photosynthetic pigments, and decreasing the contents of cellular protein and non-protein, accordingly led to the increase of malondialdehyde content, and the activities of superoxide dismutase, catalase and peroxidase in algae cells. In addition, the variation of the cellular ultrastructure indicated a serious change in algal physiology. It's revealed that the biodegradation mechanism of M. aeruginosa should primarily be that Streptomyces sp. KY-34 caused the damage of algae cell membrane and led to the increases of antioxidant enzymes, and then the growth of M. aeruginosawas inhibited.Journal of hazardous materials 08/2013; 262C:274-280. DOI:10.1016/j.jhazmat.2013.08.032 · 4.53 Impact Factor
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- "Similar to our results, Hua et al.  found that Streptomyces strain NT0401 caused a significant reduction in live M. aeruginosa cells at 5% (v/v) treatment level. The cyanobactericidal activity of microorganisms towards many kinds of cyanobacteria have also been published in other recent studies , , , and the effective removal efficiencies of Chl a were reported as approximately 50%–98% at a suitable bacterial density for more than 6 d , . However, cell viability was restored after treatment for a period of time . "
ABSTRACT: An isolated strain sp. HJC-D1 was applied to inhibit the growth of cyanobacterium FACHB-905. The effect of sp. HJC-D1 culture broth on the cell integrity and physiological characteristics of FACHB-905 was investigated using the ﬂow cytometry (FCM), enzyme activity and transmission electron microscopy (TEM) methods. Results showed that the growth of FACHB-905 was significantly inhibited, and the percentage of live cells depended on the culture broth concentration and exposure time. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased with exposure concentration and exposure time, and the significant increase of reactive oxygen species (ROS) led to the disruption of the subcellular structure of FACHB-905, and caused the increase of malondialdehyde (MDA). Furthermore, TEM observation suggested the presence of three stages (cell breakage, organelle release and cell death) for the cyanobactericidal process of sp. HJC-D1. Therefore, sp. HJC-D1 not only affected antioxidant enzyme activities and ROS level, but also destroyed the subcellular structure of FACHB-905, demonstrating excellent cyanobactericidal properties.PLoS ONE 02/2013; 8(2):e57654. DOI:10.1371/journal.pone.0057654 · 3.23 Impact Factor