title: Viability and biomass of Micrococcus luteus DE2008 at different salinity concentrations determined by specific fluorochromes and CLSM-image analysis.
abstract: In previous studies, our group developed a method based on Confocal Laser Scanning Microscopy and Image Analysis (CLSM-IA) to analyze the diversity and biomass of cyanobacteria in microbial mats. However, this method cannot be applied to heterotrophic microorganisms, as these do not have autofluorescence. In this article, we present a method that combines CLSM-IA and Hoechst 33342 and SYTOX Green fluorochromes (FLU-CLSM-IA) to determine the viability and biomass of Micrococcus luteus DE2008, isolated from a saline microbial mat (Ebro Delta, Tarragona, Spain). The method has been applied to assess the effect of salinity on this microorganism. A reduction in viability and biomass (live cells) was observed as the salt concentration increases. The largest effect was at 100‰ NaCl with a cell death of 27.25% and a decrease in total and individual biomass of 39.75 and 0.009 mgC/cm(3), respectively, both with respect to optimal growth (10 ‰ NaCl). On the other hand, another important contribution of this article was that combining the FLU-CLSM-IA results with those achieved by plate counts enabled us to determine, for first time, the viability and the total biomass of the "dormant cells" (66.75% of viability and 40.59 mgC/cm(3) of total biomass at 100‰ NaCl). FLU-CLSM-IA is an efficient, fast, and reliable method for making a total count of cells at pixel level, including the dormant cells, to evaluate the viability and the biomass of a hetetrophic microorganism, M. luteus DE2008.
authors: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona, Spain.
authors: Zully M
authors: ZM
authors: Puyen
authors: Eduard
authors: E
authors: Villagrasa
authors: Juan
authors: J
authors: Maldonado
authors: Isabel
authors: I
authors: Esteve
authors: Antonio
authors: A
authors: Solé
mesh_terms: D018533:Biomass; D005456:Fluorescent Dyes / Q000378:metabolism; D050296:Microbial Viability; D016982:Micrococcus luteus / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods*; D012965:Sodium Chloride / Q000032:analysis / Q000378:metabolism*; D013030:Spain
chemical_list: D005456:Fluorescent Dyes; D012965:Sodium Chloride