All plants have symbiotic relationships with microbes known as endophytes. These endophytes, often bacterial, live within plant tissues and help improve resiliency in the face of environmental challenges. In our changing climate, we have become increasingly dependent on the unsustainable practice of using nitrogen-based fertilizers to promote plant growth. With the hypothesis that wild plants growing in nutrient-limited sites would have endophytes particularly strong in providing nutrients to the plant host, our team collected plant tissue samples from several sites along the Bogachiel River Trail located in the Bogachiel Rainforest near Forks, WA. We successfully isolated endophytes from these samples, characterizing each strain based on their ability to grow on nitrogen-limited growth media. We used acetylene reduction assays (ARA) as a proxy to quantify nitrogenase activity levels of fast-growing microbial strains. The strains we quantified with the most nitrogen-fixing activity were collected from the primary successional zone of the river, consistent with previous findings of the UW Plant Microbiology Laboratory. We later identified these promising strains through 16S DNA sequencing, and using bioinformatics platforms, we searched for genes involved in nitrogen fixation. The properties of nitrogen-fixing endophytes can be investigated as an alternative to nitrogen-based fertilizers, sustainably increasing plant productivity in environments where nitrogen is limited. Future plant experiments can now be performed using our strong nitrogen-fixing strains to determine if these microbes have plant growth-promoting properties. The isolation and further study of endophytes like these will be crucial in the future of sustainable agriculture.

The Tacoma-Pierce County Health Department assessed six communities in Tacoma and on the peninsula that are facing limited opportunities for optimal well-being; the objective is to investigate health care quality and efficiency. These communities are called Communities of Focus (CoF). Our work explores state data to evaluate the relationship between hospital length of stay (LOS) and cause-specific hospital readmission rates (CSR) in CoF. The current literature has not reached consensus on understanding the designated relationship. Applying a multivariate logistic regression model, we explored the relationship between length of stay and CSR using data from the Comprehensive Hospital Abstract Reporting System (CHARS). Several covariates including race and gender were included in the regression model. One extra day of hospital stay resulted in a 0.5% higher risk of 30-day CSR [Odds Ratio (OR): 1.005, CI: 1.00–1.01]. The control factor substantially increasing risk of readmission, was age 55-65 years (OR: 3.477, CI: 3.19–3.79). The covariate significantly reducing CSR was being female (OR: 0.816, CI: 0.80–0.83). Individuals of Indian race (OR: 1.120, CI: 1.04–1.20, p <0.05) and Hawaiian race (OR: 1.157, CI: 1.06–1.26, p <0.0001) were more likely to experience CSR compared to White patients. Finally, CoF faced higher risk of CSR (OR: 3.973, CI: 3.77–4.19) relative to other regional patients. CSR is re-admission to the healthcare setting due to a complication or an exacerbation of disease. A single day hospital stay yielding higher risk for CSR suggests that further exploration is needed to understand patient experiences while admitted. Additionally, an investigation into the social, economic, environmental and personal factors placing CoF at risk for CSR is warranted in order to reduce risk. Our research identifies the problem; future work is needed to elucidate the source so that approaches can be identified to lower CSR for CoF.

Climate change and global population growth are driving the need for more sustainable methods for growing crops used in agriculture and the production of biofuels. To address these challenges we are exploring the role of the plant microbiome in host plant tolerance to environmental stresses related to climate change. In particular, we are investigating whether endophytes, microorganisms that colonize the internal tissues of plants, make the host plants more tolerant to drought or low-nitrogen conditions. We are currently optimizing the process of DNA extractions of fruit and poplar trees which were inoculated with beneficial nitrogen-fixing bacteria, and grown in either water or nitrogen-limited conditions. We then purify high quality microbial DNA and use polymerase-chain reaction (PCR) to optimize strain-specific primers (SSP), which target specific DNA sequences in the genomes of our endophytes in the presence of competing DNA. This allows us to gain an understanding of where they colonize, and to demonstrate that the trees were successfully colonized by our endophytes to support growth and drought tolerance data collected from inoculated and uninoculated controls. By ensuring the SSPs only target our strains of interest, we differentiate our endophytes from other members of the plant microbiome. These primers are then used in Droplet Digital PCR (ddPCR) to quantify their relative abundance. Using this information we hope to demonstrate that beneficial endophytes can be used as a sustainable method for improving drought and low nitrogen tolerance in plants, both in agricultural and biofuel applications, reducing the consumption of nitrogen fertilizers and water for irrigation in these sectors.

The field of plant microbiology has recently seen large developments in the understanding and appreciation of the internal plant microbiome. The microbes living within plants, termed endophytes, have been shown to play a vital role in many aspects of plant growth and development. These roles include nitrogen fixation, nutrient acquisition, tolerance to external stressors (such as heat or water deficit), auxin production, detoxification of harmful chemicals, and plant defense. Many of these plant growth promoting bacteria (PGPB) can be cultured and then used to inoculate new plants in order to boost these plants' health and success. However, in the course of inoculating plants with a consortium of these PGPBs, it has been found that there are inadequate and unequal levels of microbe colonization, leading to lower than expected plant health benefits. Our research has aimed to identify the causes of this poor colonization and rectify them. Strains were first grown individually and in mixed pools to identify any inhibitory relations between microbe strains, especially of key strains. My partner and I then inoculated sterile poplar (Populus sp.), with single strain inoculations, 4 two strain teams, and 2 consortiums. After poplar were allowed to grow, we tested for strain presence by plating shoot and root tissue extracts onto media and comparing to previous examples of strain growth. We then re-isolated strains in the consortiums to determine individual strain presence. Through our research, we discovered a key strain was inhibited in the old consortium and may be epiphytic rather than endophytic. We expect to see more specific interactions between strains through our two strain and consortium inoculations. Additionally, we have seen correlations between plant morphology and colonization, and expect to see more. Once complete, our results will be used to design a new consortium.