Abstract
Confocal laser scanning microscopy in combination with digital image analysis was used to assess the impact of protozoa on bacterial colonisation of surfaces. Bacterial biofilms were developed from activated sludge in microscope flow cells and were exposed to the grazing pressure of protozoa. The protozoan community from healthy activated sludge and a culture of flagellate Bodo saltans were used as grazers. Experiments comprised 48-h incubations in 3 treatment variants: bacteria with protozoa, bacteria with protozoa added after some time and bacteria without protozoa. When necessary, the elimination of protozoa from the inoculum was carried out with cycloheximide and NiSO4. Experiments demonstrated that protozoa from healthy activated sludge initially disturbed the biofilm development but later they could stimulate its growth. Similar results could be established in the experiment with Bodo saltans (inoculum: 1000 cells/ml), however differences were not statistically significant. The finding that protozoa support biofilm development during specific stages may be relevant for biofilm studies with mixed environmental biofilm communities.
References
Böckelmann U., Manz W., Neu T., Szewzyk U. 2000. Characterization of microbial community of lotic organic aggregates (‘river snow’) in the Elbe River of Germany by cultivation and molecular methods. FEMS Microbiol. Ecol. 33: 157-170.
Cole J. 1999. Aquatic microbiology for ecosystem scientists: new and recycled paradigms in ecological microbiology. Ecosystems 2: 215-225.
Hall-Stoodley L., Costerton J. W., Stoodley P. 2004. Bacterial biofilms: from the natural environment to infectious diseases. Nat. Rev. Microbiol. 2: 95-108.
Huws S. A., McBain A. J., Gilbert P. 2005. Protozoan grazing and its impact upon population dynamics in biofilm communities. J. Appl. Microbiol. 98: 238-244.
Jackson S. M., Jones E. B. G. 1991. Interactions within biofilms: the disruption of biofilm structure by protozoa. Kieler Meeresforsch. Sonderh. 8: 264-268.
Lawrence J. R., Snyder R. A. 1998. Feeding behaviour and grazing impacts of a Euplotes sp. on attached bacteria. Can. J. Microbiol. 44: 623-629.
Matz C., Webb J. S., Schupp P. J., Phang S. Y., Penesyan A., Egan S., Steinberg P., Kjelleberg S. 2008. Marine biofilm bacteria evade eukaryotic predation by targeted chemical defence. PloS ONE 3: e2744.
Packroff G., Lawrence J. R., Neu T. R. 2002. In situ confocal laser scanning microscopy of protozoans in cultures and complex biofilm communities. Acta Protozool. 41: 245-253.
Parry J. D. 2004. Protozoan grazing of freshwater biofilms. Adv. Appl. Microbiol. 54: 167-196.
Parry J. D., Holmes A. K., Unwin M. E., Laybourn-Parry J. 2007. The use of ultrasonic imaging to evaluate the effect of protozoan grazing and movement on the topography of bacterial biofilms. Lett. Appl. Microbiol. 45: 364-370.
Pederson K. 1990. Biofilm development on stainless steel and PCV surfaces in drinking water. Water Res. 24: 239-243.
Pernthaler J., Posch T., Šimek K., Vrba J., Amann R., Psenner R. 1997. Contrasting bacterial strategies to coexist with a flagellate predator in an experimental microbial assemblage. Appl. Environ. Microbiol. 63: 596-601.
Ramos C., Licht T. R., Sternberg C., Krogfelt K. A., Molin S. 2001. Monitoring bacterial growth activity in biofilms from laboratory flow chambers, plant rhizosphere, and animal intestine. Methods Enzymol. 337: 21-42.
Ratsak C. H., Maarsen K. A., Kooijman S. A. L. M. 1996. Effects of protozoa on carbon mineralization in activated sludge. Water Res. 30: 1-12.
Reasoner D. J., Geldreich E. E. 1985. New medium for the enumeration and subculture of bacteria from potable water. Appl. Environ. Microbiol. 49: 1-7.
Scheuerman P. R., Schmidt J. P., Alexander M. 1988. Factors affecting the survival and growth of bacteria introduced into lake water. Arch. Microbiol. 150: 320-325.
Sherr B. F., Sherr E. B., Andrew T. L., Fallon R. D., Newell S. Y. 1986. Trophic interactions between heterotrophic protozoa and bacterioplankton in estuarine water analysed using selective metabolic inhibitors. Mar. Ecol. Prog. Ser. 32: 169-180.
Sibille I., Sime-Ngando T., Mathieu L., Block J. C. 1998. Protozoan bacterivory and Escherichia coli survival in drinking water distribution systems. Appl. Environ. Microbiol. 64: 197-202.
Sieburth J. M., Davis P. G. 1982. The role of heterotrophic nanoplankton in the grazing and nurturing of planktonic bacteria in the Sargasso and Caribbean Seas. Ann. Inst. Oceanogr. Paris 58 (S): 285-296.
Utermöhl H. 1931. Neue Wege in der quantitativen Erfassung des Planktons. Verh. Int. Ver. Theor. Angew. Limnol. 5: 567-596.
Weitere M., Bergfeld T., Rice S. A., Matz C., Kjellenberg S. 2005. Grazing resistance of Pseudomonas aeruginosa biofilms depends on type of protective mechanism, developmental stage and protozoan feeding mode. Environ. Microbiol. 7: 1593-1601.
License
Ten utwór jest dostępny na licencji Creative Commons Uznanie autorstwa - Bez utworów zależnych 4.0 Międzynarodowe.