Response of Cylindrospermopsis raciborskii and Pseudanabaena limnetica to a potential biological control agent, bacterium SG-3 (Lysobacter cf. brunescens)

Abstract A bacterium (SG-3) was reported by Walker and Higginbotham (2000) to lyse cells of filamentous planktonic species of cyanobacteria such as Anabaena, Oscillatoria and Lyngbya. We tested the efficacy of SG-3 in the laboratory to control Cylindrospermopsis raciborskii, a species with the potential to produce toxins, and Pseudanabaena limnetica, a species that causes taste and odor problems in water. Both were susceptible to SG-3 concentrations of 1.5 × 107 PFU/mL (PFU = plaque forming units), which was consistent with the concentrations used by Walker and Higginbotham (2000). In tests with a range of SG-3 concentrations (15 to 1.5 × 107 PFU/mL), cell numbers of the Lake Yale and Lake Griffin (FL) isolates of C. raciborskii in relation to untreated controls were reduced by 89–99% at SG-3 concentrations of 1.5 × 105 PFU/mL. The Lake Griffin isolate was somewhat more sensitive to SG-3 than the Lake Yale isolate. The calculated EC50 and EC100 for the Lake Griffin strain were 1.2 × 103 PFU/mL and 3.3 × 1...