Effect of large-scale planting water hyacinth on cultivable bacterial community structure in the eutrophic lake

Abstract:

[Objective] To investigate the impact of large-scale planting water hyacinth (Eichhornia crassipes) on the cultivable bacterial community structure and diversity in the eutrophic lake. [Methods] Diluting plate counting method was applied to monitor the cultivate bacteria communities in three water hyacinth planting areas composed of purple root water hyacinth planting area (ZW), wild-type water hyacinth planting area (PW) and non-planting sites (control, CK), and then the 16S rRNA gene of the isolates were sequenced. [Results] 54, 49 and 40 isolates with various morphological characteristics were obtained from ZW, PW and CK, respectively. The Shannon-Wiener diversity indexes were 3.17, 3.07 and 2.73, respectively. And the quantities of the culturable bacterial in ZW, PW and CK were 1.35′107 CFU, 8.35′106 CFU, 2.70′106 CFU of per Liter, respectively. The 16S rRNA sequencing result showed that at the common and dominant phylum species among the three sampling sites were Alphaproteobacteria, which accounting for 35.1%, 32.4% and 40.0% of total culturable bacteria, and Actinobacteria which accounting for 18.9%, 32.4% and 20.0%, and Betaproteobacteria which accounting for 13.5%, 5.9% and 16%, and Gammaproteobacteria which accounting for 13.5%, 14.6% and 12.0%, and Bacteroidetes which accounting for, 13.5%, 8.8% and 8.0%, and Firmicutes which accounting for 2.7%, 5.9% and 4.0%, respectively. Only ten genera Sphingopyxis, Rhodobacter, Xanthobacter, Novosphingobium, Sphingomonas, Pseudomonas, Microbacterium, Steptomyces, Flavobacterium and Bacillus were shared by all the three water samples. [Conclusion] This study indicates that large-scale planting water hyacinth could both increase the cultivated bacterial diversity and modify the bacterial community composition in the eutrophic lake.