title: Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity.
abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1-3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms.
authors.affiliation: International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand; Center of Excellence on Hazardous Substance Management, Bangkok 10330, Thailand. Electronic address: pumis.th@gmail.com.
authors.forename: Pumis
authors.initials: P
authors.lastname: Thuptimdang
authors.affiliation: Center of Excellence on Hazardous Substance Management, Bangkok 10330, Thailand; Department of Environmental Engineering, Chulalongkorn University, Bangkok 10330, Thailand; Research Unit Control of Emerging Micropollutants in Environment, Chulalongkorn University, Bangkok 10330, Thailand. Electronic address: tawan.l@chula.ac.th.
authors.forename: Tawan
authors.initials: T
authors.lastname: Limpiyakorn
authors.affiliation: Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108, USA. Electronic address: john.mcevoy@ndsu.edu.
authors.forename: John
authors.initials: J
authors.lastname: McEvoy
authors.affiliation: Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108, USA. Electronic address: birgit.pruess@ndsu.edu.
authors.forename: Birgit M
authors.initials: BM
authors.lastname: Prüß
authors.affiliation: Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58108, USA. Electronic address: eakalak.khan@ndsu.edu.
authors.forename: Eakalak
authors.initials: E
authors.lastname: Khan
mesh_terms: D000244:Adenosine Diphosphate / Q000032:analysis / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D053768:Metal Nanoparticles; D016958:Pseudomonas putida / Q000187:drug effects* / Q000254:growth & development; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000302:isolation & purification; D018030:Silver Compounds / Q000494:pharmacology*
chemical_list: D012329:RNA, Bacterial; D018030:Silver Compounds; D000244:Adenosine Diphosphate
keywords: Biofilm maturity; Biofilms; Extracellular polymeric substance; Silver nanoparticles