(32d) Rapid Identification of Optimized Plant Growth Promoting Formulations Using Microwell Arrays to Enhance Biofertilizer Production

In order to improve the use of plant growth promoting rhizobacteria (PGPR), researchers need to gain a fundamental understanding of the factors that influence PGPR survival, growth, and function in the rhizosphere. In this research we are using microwell arrays to study interactions between the PGPR species Pantoea sp. YR343, a rhizobacteria that promotes plant growth by producing the phytohormone indole-3-acetic acid, and isolates from Populus deltoides roots in effort to develop PGPR-based biofertilizers for use on poplar trees. With rapid growth in diverse climates and inherently high stress resistance, P.deltoides has a high potential for use as a biomass/bioenergy feedstock. Also, because of the availability of rich amounts of genomic resources for Populus species, genomic modifications are possible to achieve improved lignocelloulosic content. The microwell array is designed as a high-throughput tool to analyze interaction networks within microbial communities by randomly combining a fluorescently-labeled PGPR species with a controlled number of community isolates after they are seeded into microwell co-culture chambers. Motile bacteria cells are trapped in microwell arrays using a crosslinked, photo-degradable polyethylene glycol hydrogel membrane and then cultured and monitored for growth using fluorescence time-lapse microscopy. We then use an in-house computational image analysis tool to detect outlier wells where PGPR growth rates appear accelerated. Finally, cellular networks are removed from outlier wells and extracted samples are 16S rRNA sequencing to identify and characterize the symbiotic microbial network present. In this presentation, we will report our findings when screening Pantoea sp. YR343 with P.deltoides isolates using this experimental platform. The findings from our research will inform new PGPR formulations that can be used to improve plant health and productivity for biofuel crops.