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Title: Microbial community structures in algae cultivation ponds for bioconversion of agricultural wastes from livestock industry for feed production

item Ibekwe, Abasiofiok - Mark
item MURINDA, SHELTON - California Polytechnic State University
item MURRY, MARCIA - California Polytechnic State University
item SHWARTZ, GREGORY - California Polytechnic State University
item LUNDQUIST, TRYGVE - California Polytechnic State University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2016
Publication Date: 12/18/2016
Citation: Ibekwe, A.M., Murinda, S.E., Murry, M.A., Shwartz, G., Lundquist, T. 2016. Microbial community structures in algae cultivation ponds for bioconversion of agricultural wastes from livestock industry for feed production. Science of the Total Environment. 580(2017):1185-1196. doi: 10.1016/j.scitotenv.2016.12.076.

Interpretive Summary: There is a critical and urgent need to control manure-derived greenhouse gases and nutrient pollution from concentrated animal feeding operations (CAFOs) while reclaiming water and nutrients, and at the same time allow competitive animal production in a global market. However, technologies and methods to reclaim nutrients from waste water, with minimal environmental impact, have not kept pace with CAFO development. In this study, we used a leading candidate technology for accelerated manure nutrient recycling — algae-based animal feeds bioconversion ponds that may play a significant role in the conversion of manure nu¬trients to animal feed where land area for traditional crops or for manure disposal is limited. The algae ponds were paddle-wheeled, mixed raceways that simulate standard 30-cm deep algae production ponds. The main objective of our study was to examine seasonal microbial community compositions in the ponds used for the production of algae biomass, and to determine co-existing bacterial taxa with potential negative or positive effects on algal growth. Our results showed that algal growth is a function of different microbial groups facilitating the conversion of dairy effluent nitrogen (N) and phosphate (P) to algae biomass thus facilitating the removal of N and P from animal waste and improving the final effluent’s water quality. The technology provides many advantages to society as a whole by affording better quality water with reduced N and P that could contaminate ground and surface water, build algal biomass that may be used as animal feed or biofuel energy source. This information will be of interest to water utility agencies, US-Department of Agriculture (USDA), US-Environmental Protection Agency (USEPA), US-Department of Energy (DOE), the World Health Organization(WHO), and the dairy industry.

Technical Abstract: Dynamics of seasonal microbial community compositions in algae cultivation ponds are complex. There is very limited knowledge on community compositions that may play significant roles in the bioconversion of manure nu¬trients to animal feed. Algae production is an alternative where land area for production of traditional crops is limited. In this study, water samples were collected from the dairy effluent lagoon, algae ponds, and municipal waste water treatment plant (WWTP) effluent for the analysis of total bacteria, Cyanobacteria, and microalgae communities using MiSeq Illumina sequencing targeting the 16S V4 rDNA region. DNA was extracted from the different sample types using three commercially available DNA extraction kits; MoBio Power water extraction kit, Zymo fungi/bacterial extraction kit, and MP Biomedicals FastDNA SPIN Kit. Permutational analysis of variance (PERMANOVA) using distance matrices on each variable showed significant differences (P = 0.001) in beta-diversity based on sample source, but no significant differences (P = 0.268) based on DNA extraction kits, suggesting that sample type was the main driver for the microbiome differences in the sample set. After removing operational taxonomic units (OTUs) unclassified at the genus level, the MPBio , MoBio and Zymo kits yielded 302, 187 and 280 taxa, respectively. DNA samples isolated from the Zymo kit had a higher proportional abundance of Chlamydomonadaceae, a family of microalgae. Our data suggest that care must be taken in choosing DNA extraction procedures when evaluating specific groups of microbial communities for specific functions.