Bacilysin from Bacillus amyloliquefaciens FZB42 Has Specific Bactericidal Activity against Harmful Algal Bloom Species

Abstract

bHarmful algal blooms, caused by massive and exceptional overgrowth of microalgae and cyanobacteria, are a serious environmental problem worldwide. In the present study, we looked for Bacillus strains with sufficiently strong anticyanobacterial activity to be used as biocontrol agents. Among 24 strains, Bacillus amyloliquefaciens FZB42 showed the strongest bactericidal activity against Microcystis aeruginosa, with a kill rate of 98.78%. The synthesis of the anticyanobacterial substance did not depend on Sfp, an enzyme that catalyzes a necessary processing step in the nonribosomal synthesis of lipopeptides and polyketides, but was associated with the aro gene cluster that is involved in the synthesis of the sfp-independent antibiotic bacilysin. Disruption of bacB, the gene in the cluster responsible for synthesizing bacilysin, or supplementation with the antagonist N-acetylglucosamine abolished the inhibitory effect, but this was restored when bacilysin synthesis was complemented. Bacilysin caused apparent changes in the algal cell wall and cell organelle membranes, and this resulted in cell lysis. Meanwhile, there was downregulated expression of glmS, psbA1, mcyB, and ftsZ-genes involved in peptidoglycan synthesis, photosynthesis, microcystin synthesis, and cell division, respectively. In addition, bacilysin suppressed the growth of other harmful algal species. In summary, bacilysin produced by B. amyloliquefaciens FZB42 has anticyanobacterial activity and thus could be developed as a biocontrol agent to mitigate the effects of harmful algal blooms. Eutrophication of surface waters has many undesirable effects and can lead to major water quality issues in freshwater and coastal systems (1). This phenomenon results in blooms of harmful algal species in freshwater lakes and brackish waters throughout the world. Moreover, the excessive growth of harmful algae, such as microalgae and cyanobacteria, often increases the production of inherent toxins such as microcystins and nodularins that cause acute poisonings of fish, birds, and mammals, including humans (2). For example, dogs died after they were exposed to a cyanobacterial bloom of Microcystis aeruginosa in Lake Amstelmeer (The Netherlands), and the concentration of microcystin in this lake was up to 5.27 ϫ 10 3 g g Ϫ1 of dry weight (3). In recent years, harmful algal blooms of eutrophic water in China have occurred frequently, including in Lake Taihu and Lake Chaohu, and Microcystis is thought to be the dominant bloom genera (4).Many control techniques have been used to prevent and mitigate bloom problems, including yellow loess (5), clay (6), and chemical agents such as copper sulfate and hydrogen peroxide (7). However, each of the physical and chemical methods available to remediate eutrophic water is associated with certain disadvantages (8). Therefore, there is still a pressing need for environmentally friendly, cost-effective, and convenient bactericidal agents directed against cyanobacterial blooms in eutrophic lakes. Biological control agents such as bact...

Cyanophages Infection of Microcystis Bloom in Lowland Dam Reservoir of Sulejów, Poland

“…An excessive increase in cyanobacterial mass known as the Bbloom of blue-green algae^leads to a disruption of aquatic ecosystems owing to the production of cyanobacterial toxins (including hepatotoxins, neurotoxins, cytotoxins, and dermatotoxins), consumption of large amounts of oxygen during cell decomposition, growth of primary production, reduction of water clarity, deterioration of organoleptic parameters, and the consequent decrease in biodiversity [5,6]. Therefore, improving our understanding of the impact of the environment on the development and activity of cyanobacteria is necessary to enable the use of its natural potential, in particular, biological control agents such as bacteria, viruses, and protozoa [7][8][9] to limit the associated threat.…”

Genome mining and UHPLC–QTOF–MS/MS illuminate the potential antimicrobial active compounds and specificity of biosynthetic gene clusters in Bacillus subtilis NCD-2

“…Microorganisms and culture conditions B. subtilis NCD-2 was routinely grown at 37 °C on Luria Bertani medium. For lipopeptide, bacillaene, bacilysin, bacillibactin and subtilosin production, strain NCD-2 was grown in Landy broth [63], PA medium [64], MSA medium [65], and TSB medium [66] at 30 ℃ and 180 rpm. Phytopathogen Botrytis cinerea BC-10 was used for antifungal activity test following the method described by Guo et al [29] with some modi cations.…”

Bactericidal metabolites from Phellinus noxius HN-1 against Microcystis aeruginosa

“…M. aeruginosa NIES-843 was purchased from the Freshwater Algae Culture Collection of the Institute of Hydrobiology (Wuhan, China) and cultured in sterilized BG11 medium at 25 ± 1 °C under a 12 h: 12 h (light: dark) cycle with 60 μmol photons m −2 s −1   5 .…”

“…It causes economic losses to aquaculture industry, water pollution, and harms to wildlife and human health 5, 6 . However, traditional control strategies usually induce the secondary pollution due to the release of phytotoxins 6–8 .…”