Using autochthonous Bdellovibrio as a predatory bacterium for reduction of Gram-negative pathogenic bacteria in urban wastewater and reuse it

Abstract

Background and Objectives: The microbial contamination of wastewater is associated with health risks. The aim of this study was to use the autochthonous Bdellovibrio potential to prey Gram-negative pathogenic bacteria as a bio-control agent to treat urban wastewater.
 Materials and Methods: Thirty-six raw sewage samples were collected for isolation of Bdellovibrio. Double layer plaque assay was used for isolation and the isolates were identified by microscopic examination and molecular analysis. To evaluate the predatory potential for decrease number of Gram-negative pathogenic bacteria, plaque perdition assay, reduction in host cells viability by colony-forming unit (CFU) counting, reduction in optical density (OD) in co-cultures and assay of killing efficiency were carried out. Also, the raw wastewater was treated by Bdellovibrio then the reduction in CFU counting and reduction in OD was evaluated.
 Results: Four strains of Bdellovibrio were isolated and were registered in Gene Bank. Clear plaques were observed after 3-6 days of incubation for all prey cells. The CFU enumerations of all preys were decreased after 48 hrs in co-cultures and raw wastewater. Also, OD was decreased down to 0.2 nm after 48 hrs.
 Conclusion: These autochthonous Bdellovibrio strains are proposed to use for bio-control of Gram-negative pathogenic bacteria in wastewater and reuse it for irrigation in arid regions.

In vitro study of the modulatory effects of heat-killed bacterial biomass on aquaculture bacterioplankton communities

“…BALO isolated from fishponds have been reported to contribute to fish health and growth performance, by reducing the incidence of diseases caused by Aeromonas hydrophila and V. alginolyticus 69 . Recent studies have attempted to control bacterial pathogens in aquaculture systems by using BALO cultures to increase their abundance in the rearing water 70 , 71 . However, some bioaugmentation strategies are thought to be ineffective due to the maladaptation of allochthonous inoculums to the new environment, where local abiotic conditions and the resident microbial community may impede their establishment and proliferation 72 , 73 .…”

Predatory efficacy of Bdellovibrio stolpii isolated from the wastewater sources against the multidrug-resistant clinical isolates

“…The inability of other remaining Bdellovibrio species to prey on other host cells could also be due to its structural features, which inhibit attachment, penetration or replication or may be due to the escape strategy of the host cell, which is not studied in the present study. Recent studies demonstrated applications of Bdellovibrio strains in biological wastewater treatment for reducing the burden of Gram-negative bacteria (Wu et al 2019;Jafarian et al 2020).…”