Community-Level Assessment of the Effects of the Broad-Spectrum Antimicrobial Chlorhexidine on the Outcome of River Microbial Biofilm Development

Abstract

Chlorhexidine is a common-use antibacterial agent found in a range of personal-care products. We used rotating annular reactors to cultivate river biofilms under the influence of chlorhexidine or its molar equivalent in nutrients. Studies of the degradation of [ 14 C]chlorhexidine demonstrated that no mineralization of the compound occurred. During studies with 100 g liter ؊1 chlorhexidine, significant changes were observed in the protozoan and micrometazoan populations, the algal and cyanobacterial biomass, the bacterial biomass, and carbon utilization. Denaturing gradient gel electrophoresis (DGGE) in combination with statistical analyses showed that the communities developing under control and 100 g liter ؊1 chlorhexidine were significantly different. At 10 g liter ؊1 chlorhexidine, there was significantly increased algal and cyanobacterial biomass while the bacterial biomass was not significantly affected (P < 0.05). No significant effects on protozoan or metazoan grazing were detected at the 10-g liter ؊1 chlorhexidine level. Fluorescent in situ hybridization indicated a significant reduction in the abundance of betaproteobacteria and gammaproteobacteria (P < 0.05). Archaeal cell counts were significantly reduced by both chlorhexidine and nutrient treatments. DGGE and statistical analyses indicated that 10 g liter ؊1 chlorhexidine and molar equivalent nutrient treatments were significantly different from control communities. In contrast to community level observations, toxicological testing with a panel of cyanobacteria, algae, and protozoa indicated no detectable effects at 10, 50, and 100 g liter ؊1 chlorhexidine. Thus, community level assessment indicated a risk of low levels of chlorhexidine in aquatic habitats while conventional approaches did not.

Bacterial community characteristics under long-term antibiotic selection pressures

“…in Bacteroidetes (Knarreborg et al, 2002;Young and Schmidt, 2004;Jernberg et al, 2005 (Antonopoulos et al, 2009;Rea et al, 2011). Lawrence et al have observed a significant reduction in the abundance of Betaproteobacteria and Gammaproteobacteria in river biofilm communities exposed to a broadspectrum antimicrobial chlorhexidine using fluorescent in situ hybridization (Lawrence et al, 2008), whereas no more information has been provided about the other bacteria groups in their research. Then in the study of Có rdova- Kreylos and Scow (2007), sulfate-reducing bacteria belonged to Deltaproteobacteria including Desulfovibrio, Desulfobacter and Desulfobulbus were obviously favored by ciprofloxacin in the sedimental microbial communities.…”

Susceptibility of cariogenic microorganisms to phytoconstituents

“…However, given the limitations of this agent, (such as staining of the tooth surface, taste changes, and micro-biotic imbalances), other, naturally occurring agents have been investigated (Lawrence et al, 2008;Khan et al, 2009).…”

APLIKASI PROBIOTIK Aeromonas sobria A3-51 UNTUK REKAYASA NUTRISI DAN IMUNOMODULASI PERIFITON PAKAN ALAMI IKAN TILAPIA

“…Dengan adanya substrat maka biofilm terbentuk oleh inisiasi sel-sel bakteria, substansi eksopolisakarida (glikokaliks) yang digunakan untuk melekat akan menjadi pelekat dan atraktan bagi mikroorganisme lain termasuk alga (Lawrence et al, 2008). Bakteri, alga dan protozoa dan sebagainya selanjutnya akan membentuk biomassa perifiton, dengan demikian produktivitas primer kolom air yang sedikit rendah disebabkan sebagian Gambar 2.…”