February 5, 2016
Assessing the Use of Food Waste Biochar as a Biodynamic Plant Fertilizer
Rachel Mazac '16
Biochar is a charcoal-like substance produced from plant material such as food waste. Converting food waste into a useful product would mitigate environmental damage through reduced landfill inputs, reduced greenhouse gas production, and increased benefits to soils. We asked (1) if biochar improved plant growth and (2) if the effects of biochar varied among different samples of mixed food waste (batches) and between different biochar preparation times (treatments). Four independent batches of biochar were prepared with assorted, uncooked food waste collected from a university dining facility. Each batch was dried then placed in a covered ceramic pot at 260 C for 3 and 6 hours under low oxygen (pyrolysis). 204 tomato (Solanum lycopersicum) were grown with the eight batch-treatment combinations or with no biochar (controls). Averaging over batches, the 3 and 6 hour treatments germinated significantly later than controls. Aboveground dry mass at 30 days did not differ significantly among the three treatments. Mean height growth rates (mm/day) were significantly higher in 3 and 6 hour treatments than in controls. Considering only biochar-treated plants, there was a significant interaction between pyrolysis time and batch for both germination time and height growth rate. Some batches germinated earlier when the biochar pyrolyzed for 3 hours was added, other batches when 6 hour biochar was added. Plants emerging later had faster height growth rates, leading to no significant difference in size at 30 days. Both pyrolysis time and food waste source material had varying effects on plant growth. While biochar had no effect on mean biomass at 30 days, complex effects on germination time and growth rate suggest that growing plants to maturity may lead to differences in plant size. Future studies should investigate effects of different food waste types on plant growth and assess nutrient content of source material.
The Gut Micobiome as a Marker to Determine Postmortem Interval
Gabriel Drees '16
Human-associated microbial communities have been noted to success postmortem in a fashion that can be reproduced, similar to entomology. This is being considered as another method in determining postmortem interval (PMI). This study evaluates the human gut bacterial populations (specifically Bacteroides, Lactobacillus, and Bifidobacterium) to determine if any significant time-dependent changes occur postmortem. Samples of gut microflora were collected from the proximal large intestine of 12 deceased human individuals as they decayed under environmental conditions. Group-specific primers targeted 16S rRNA genes to quantify the 3 bacterial genera using qPCR. A statistically significant (p < 0.001) exponential decrease in relative abundance for Bacteroides and Lactobacillus was observed with an increase in PMI. The relative abundance of Bifidobacterium did not have a significant change (p < 0.284). This study determined that Bacteroides and Lactobacillus relative abundances has the potential to be used as another measure to determine PMI for forensic analysts.