Bacterial community of the rice floodwater using cultivation-independent approaches

Authors: PITTOL, MICHELLE - Universidade Do Vale Do Rio Dos Sinos (UNISINOS); Scully, Erin; Miller, Daniel; Durso, Lisa; VALIATI, VICTOR - Universidade Do Vale Do Rio Dos Sinos (UNISINOS); FIUZA, MARIANA - Universidade Do Vale Do Rio Dos Sinos (UNISINOS)

Submitted to: International Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2017
Publication Date: 1/30/2018
Citation: Pittol, M., Scully, E.D., Miller, D.N., Durso, L.M., Valiati, V.H., Fiuza, M.L. 2018. Bacterial community of the rice floodwater using cultivation-independent approaches. International Journal of Microbiology. 2018:Article ID 6280484, 13pgs. https://doi.org/10.1155/2018/6280484.
DOI: https://doi.org/10.1155/2018/6280484

Interpretive Summary: Bacteria are an important part of the rice production system. Some bacteria are symbionts of rice, and help the rice plants obtain nutrients. Other bacteria live in the water and soil of rice fields, and potentially contribute to nutrient cycling in rice production. Here, we compare the bacterial communities in rice production water during two stages of rice growth, specifically the vegetative and reproductive stages of the rice. There were more than twice as many different types of bacteria in the vegetative compared to the reproductive stage samples. One possible reason for this might be because the rice production waters are rich with nutrients during the vegetative growth phase. Some of the bacteria found in the rice production waters have been previously detected in fresh water systems, and the soil, roots, and leaves of rice plants. This work provides new information on the bacteria present in rice paddy water during two important stages of rice growth.

Technical Abstract: In agricultural systems, interactions between plants and symbiotic microorganisms are important to maintaining production and profitability. In addition, the water layer and its interface with the soil play an important role in rice plant nutrition while nutrients levels in floodwaters can shape environmental factors that influence soil microbial community structure and composition. In this study, bacterial communities of water layers of rice fields were monitored during the vegetative and reproductive stages of rice plant development using 16S amplicon sequencing. The study was conducted in flooded rice fields located in the city of Viamão, RS, Brazil, during crop years 2011/12 and 2012/13. Comparative analyses showed that the richness and composition of the bacterial communities differed between water layers sampled during the vegetative and reproductive stages of rice. During the vegetative stage, the number of operational taxonomic units (OTUs) detected was 1551 while less than half that number (603) were identified in the reproductive stage. Eighteen bacterial phyla were identified in water sampled from both stages and the richest phylum was Proteobacteria which contained 53.34% of the OTUs. The higher bacterial richness observed in water layer collected during the vegetative stage may have been favored by the higher concentration of nutrients, such as phosphorus and potassium, due to rhizodeposition and fertilizer application. In this study, the low amount of shared OTUs observed between flood waters collected from vegetative and reproductive stage indicates that bacterial communities change temporally and that some bacterial taxa can be related to a particular rice growth stage. The richness of bacterial communities over cultivation time may contribute to the sustainability of the crop by regulating the soil quality and biogeochemical activities.