Bacteriophage ecology in Escherichia coli and Pseudomonas aeruginosa mixed-biofilm communities.
Phage therapy is being reexamined as a strategy for bacterial control in medical and other environments. As microorganisms often live in mixed populations, we examined the effect of Escherichia coli bacteriophage λW60 and Pseudomonas aeruginosa bacteriophage PB-1 infection on the viability of monoculture and mixed-species biofilm and planktonic cultures. In mixed-species biofilm communities, E. coli and P. aeruginosa maintained stable cell populations in the presence of one or both phages. In contrast, E. coli planktonic populations were severely depleted in coculture in the presence of λW60. Both E. coli and P. aeruginosa developed phage resistance in planktonic culture; however, reduced resistance was observed in biofilm communities. Increased phage titers and reduced resistance in biofilms suggest that phage can replicate on susceptible cells in biofilms. Infectious phage could be released from mixed-culture biofilms upon treatment with Tween 20 but not upon treatment with chloroform. Tween 20 and chloroform treatments had no effect on phage associated with planktonic cells, suggesting that planktonic phage were not cell or matrix associated. Transmission electron microscopy showed bacteriophage particles to be enmeshed in the extracellular polymeric substance component of biofilms and that this substance could be removed by Tween 20 treatment. Overall, this study demonstrates how mixed-culture biofilms can maintain a reservoir of viable phage and bacterial populations in the environment.
Department of Biology, Texas State University-San Marcos, 601 University Drive, San Marcos, TX 78666, USA.
Matthew K
MK
Kay
Thomas C
TC
Erwin
Robert J C
RJ
McLean
Gary M
GM
Aron
D018441:Biofilms / Q000254:growth & development*; D003090:Coliphages / Q000254:growth & development* / Q000502:physiology; D015169:Colony Count, Microbial; D003470:Culture Media; D017753:Ecosystem; D004926:Escherichia coli / Q000254:growth & development / Q000821:virology; D050296:Microbial Viability; D010933:Plankton / Q000254:growth & development; D017105:Pseudomonas Phages / Q000254:growth & development* / Q000502:physiology; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000821:virology
D003470:Culture Media