A flow cytometer based protocol for quantitative analysis of bloom-forming cyanobacteria (Microcystis) in lake sediments
Quan Zhou , Wei Chen , Huiyong Zhang , Liang Peng , Liming Liu , Zhiguo Han , Neng Wan , Lin Li , Lirong Song
DOI:10.1016/S1001-0742(11)60993-5
Received November 06, 2011,Revised March 20, 2012, Accepted , Available online September 07, 2012
Volume 24,2012,Pages 1709-1716
A quantitative protocol for the rapid analysis of Microcystis cells and colonies in lake sediment was developed using a modified flow cytometer, the CytoSense. For cell enumeration, diluted sediment samples containing Microcystis were processed with sonication to disintegrate colonies into single cells. An optimized procedure suggested that 5 mg dw (dry weight)/mL dilution combined with 200 W × 2 min sonication yielded the highest counting efficiency. Under the optimized determination conditions, the quantification limit of this protocol was 3.3×104 cells/g dw. For colony analysis, Microcystis were isolated from the sediment by filtration. Colony lengths measured by flow cytometry were similar to those measured by microscopy for the size range of one single cell to almost 400 μupm in length. Moreover, the relationship between colony size and cell number was determined for three Microcystis species, including Microcystis flos-aquae, M. aeruginosa and M. wessenbergii. Regression formulas were used to calculate the cell numbers in different-sized colonies. The developed protocol was applied to field sediment samples from Lake Taihu. The results indicated the potential and applicability of flow cytometry as a tool for the rapid analysis of benthic Microcystis. This study provided a new capability for the high frequency monitoring of benthic overwintering and population dynamics of this bloom-forming cyanobacterium.
