Effects of recycled water irrigation on bacterial community compositions in lawn soil

Abstract:

Abstract: [Objective] In order to obtain the information about how irrigations with recycled water affecting the cultivable microbial population of the rhizosphere of turfgrasses, [Methods] We isolated strains from two irrigated areas with recycled water (RW) and drinking water (DW) in Taoranting Park in Beijing, China, by using diluting plate and counting method, and analyzing the 16S rDNA sequence of the isolates. [Results] We obtained 20 and 25 strains with different morphological character of colonies from the area irrigated with DW and area irrigated with RW, respectively. The sequence analysis of 16SrDNA showed that RW-irrigated system supported more complex communities of 18 genus and 24 species, whereas the DW-irrigated system only supported 15 genus and 20 species. Both samples had similar microbial population. There were 9.7% or 13.4% alphaproteobacteria, 8.1% or 12.3% betaproteobacteria, 17.9% or 42.0% gammaproteobacteria, 13.0% or 2.9% bacteroidetes, 23.6% or 10.1% firmicutes, and 27.6% or 19.6% actinobacteria at the rhizosphere of turfgrasses irrigated with DW or RW respectively. The dominant bacteria in DW area were the genera Bacillus whereas that of RW area was the genera Acinetobacter. Other than the gammaproteobacteria, the dominant genera in other groups of two areas were similar. [Conclusion] The result showed that the bacterial community composition of rhizosphere samples did not change, but the distribution of different types of bacteria does change after irrigation by reclaimed water, which were determined by the abundance increasing of the dominant species and the appearance or disappearance of non-dominant species. Finally, it is important that the control of the pathogen and metal should be enforced when using RW for irrigation.