Ubiquitous and promising: new potential biocontrol BALOs (Bdellovibrio and like organisms) species, isolated from water and soil samples in Iran

Among predatory bacteria, Bdellovibrio and Like Organisms (BALOs) have a high potential for application as biocontrol agents. The objective of this study was to isolate and characterize native BALO strains from different water and soil samples in Iran. Nineteen BALO strains were obtained from the samples using Escherichia coli as prey. Analysis of 16S rRNA gene sequences showed that Na2, Tal2, Mm1, and Ja2 strains belong to a different species than B. bacteriovorus HD100 as a type strain. Also, Z2, B2, Ch2, Kan1, and Pj strains could be separate from the Bdellovibrio genera. The strains showed different host range and predation efficiency when they were tested with 17 different Gram-negative bacteria subsequently. The prey range of six strains including Sar, Pj, Kan1, C1, Z2, and Ch2 was limited to only E. coli. The most versatile predators were strains Zar3 and Kash2 that exhibited almost the same prey range as type strain HD100. They are also placed close to each other in the phylogenetic tree. The host range of strain Na2 was narrow and attacked only Ralstonia solanacearum, which is less susceptible to predation by the other strains. Native BALOs from water and soils in Iran were isolated, forming a group of potential biocontrol agents adapted to local conditions.