Algicidal bacterium CZBC1 inhibits the growth of Oscillatoria chlorina, Oscillatoria tenuis, and Oscillatoria planctonica

Abstract

Frequent harmful cyanobacteria blooms limit the sustainable development of aquaculture. Algicidal bacteria can efficiently control harmful algae without secondary pollution. The algicidal bacteria CZBC1 can lyse Oscillatoria spp. and other harmful cyanobacteria, but its effector mechanism and algicidal threshold are unknown. In this study, we examined the algicidal effect of CZBC1 on O. chlorina, O. tenuis, and O. planctonica by microscopic enumeration and scanning electron microscopy observation. Then, we examined the alginolytic effects of CZBC1 (concentrations 103–106 colony forming units (cfu)/mL) on these three species (concentrations 103–106 cells/mL) to determine the effective concentrations of CZBC1 for Oscillatoria spp. alginolysis. Results showed that CZBC1 can directly lyse O. chlorina and O. tenuis but indirectly lyse O. planctonica. When the initial concentration of CZBC1 was 106 cfu/mL, alginolytic effects were high for all three species at all concentrations, and the alginolytic rate could reach 100% in 3–9 days. When the initial concentration of CZBC1 was lower (103 cfu/mL), its inhibitory effects were delayed by 2–5 days, but the cell counts were significantly decreased compared with the control, evidencing significant alginolysis. In addition, the higher the concentration of the algicidal bacteria suspension, the more significant the alginolytic effects. Our results indicate that CZBC1 has different alginolytic mechanisms for O. chlorina, O. tenuis, and O. planctonica, and that different initial concentrations of CZBC1 have different alginolytic effects on these algal species.

Simultaneous biodegradation of harmful Cylindrospermopsis raciborskii and cylindrospermopsin toxin in batch culture by single Bacillus strain

“…For C. raciborskii, this is the rst study investigating the algicidal and lytic activity of a bacterial strain against this toxic cyanobacterium. Generally, the mechanisms underlying the inhibitory and lysing activity of algicidal bacteria can be through direct physical contact between bacterial and cyanobacterial cells, or indirectly via excretion of extracellular chemicals or enzymes by bacteria into the surrounding medium (Luo et al 2013;Lee et al 2018, Hu et al 2019. In this study, the ltrate of bacterial strain SSZ01 inhibited the growth of C. racibrskii during the rst day of incubation, while the inhibition and lysis of C. raciborskii cells co-cultivated with SSZ01 cells commenced after 3 days of incubation.…”

“…The results showed that the co-cultivation of C. raciborskii with bacterial cells resulted in the reduction of C. raciborskii cell density, with complete cell lysis within 5 days. The removal e ciency of C. raciborskii cells by our bacterial strain can be compared to that of the strongest algicidal bacteria reported in previous studies, such as Aeromonas and Bacillus, which completely removed and lysed cyanobacterial cells of M. aeruginosa and Oscillatroia planctonica from 5 to 6 days (Lee et al 2018, Hu et al 2019Yang et al 2020). For C. raciborskii, this is the rst study investigating the algicidal and lytic activity of a bacterial strain against this toxic cyanobacterium.…”

“…against M. aeruginosa also re ected this trend of algicidal mechanism (Yang et al 2020). Similarly, Oscillatoria planctonica cells were lysed by extracellular products of Bacillus cereus CZBC1 (Hu et al 2019). Most of these studies demonstrated that the lytic activity of algicidal bacteria are associating with initial cell density of bacteria (Hu et al 2019;Yang et al 2020).…”

“…Similarly, Oscillatoria planctonica cells were lysed by extracellular products of Bacillus cereus CZBC1 (Hu et al 2019). Most of these studies demonstrated that the lytic activity of algicidal bacteria are associating with initial cell density of bacteria (Hu et al 2019;Yang et al 2020). Concomitant with these studies, our results revealed that strain SSZ01 with initial cell density of 10 6 cfu ml -1 exhibited strong and rapid aligicidal activity against C. raciborskii, but when its initial cell density was lower (10 3 cfu ml -1 ), its inhibitory effects were weak with no complete death of cyanobacterial cells.…”

Simultaneous Biodegradation of Harmful Cylindrospermopsis Raciborskii and Cylindrospermopsin Toxin in Batch Culture by Single Bacillus Strain

“…against M. aeruginosa also re ected this trend of algicidal mechanism (Yang et al 2020). Similarly, Oscillatoria planctonica cells were lysed by extracellular products of Bacillus cereus CZBC1 (Hu et al 2019). Most of these studies demonstrated that the lytic activity of algicidal bacteria are associating with initial cell density of bacteria (Hu et al 2019;Yang et al 2020).…”