Departamento de Edafología y Química Agrícola

The effect of the microalgae-bacteria microbiome on wastewater treatment and biomass production

The effect of the microalgae-bacteria microbiome on wastewater treatment and biomass production Paddock, Matthew; Fernández Bayo, Jesús Dionisio; VanderGheynst, Jean S. The use of microalgae for wastewater treatment has been proposed as a cost-effective method to produce biofuels while remediating waste streams. This study examined the microalgae biomass production rate, wastewater treatment efficiency, and prokaryotic organism microbiome associated with microalgae Chlorella sorokiniana cultivated on anaerobic digestate effluent. Final microalgae biomass concentrations from nine photobioreactors were highly variable and had values that ranged between 0.14 g/L and 0.90 g/L. Nutrient removal efficiencies for TN (total nitrogen), N-NH4 (ammonium nitrogen), and COD (chemical oxygen demand) ranged from 34% to 67%, 65% to 97%, and−60% to 14%, respectively. Analysis of individual OTUs (operational taxonomic units) from the microbial community revealed that microalgae biomass concentrations were significantly correlated with the relative abundance of OTUs in the genus Pusillimonas. Predictive metagenomic analyses identified additional correlations associated with biomass production and nutrient removal. These results suggest that the microbial community present during microalgae cultivation on wastewater can impact the performance of the system for biomass production and wastewater treatment.

Effect of management of organic wastes on inactivation of Brassica nigra and Fusarium oxysporum f.sp lactucae using soil biosolarization

Effect of management of organic wastes on inactivation of Brassica nigra and Fusarium oxysporum f.sp lactucae using soil biosolarization Fernández Bayo, Jesús Dionisio; Randall, Tara E.; Harrold, Duff R.; Achmon, Yigal; Hestmark, Kelley V.; Su, Joey; Dahlquist-Willard, Ruth M.; Gordon, Thomas R.; Stapleton, James J.; VanderGheynst, Jean S.; Simmons, Christopher W. BACKGROUND: Soil biosolarization is a promising alternative to conventional fumigation. Volatile fatty acids (VFAs) produced in the soil through fermentation of amended organic matter can affect pest inactivation during biosolarization. The objective was to determine how soil amended with organic wastes that were partially stabilized through either composting or anaerobic digestion affected the inactivation of Brassica nigra (BN; a weed) and Fusarium oxysporum f. sp. lactucae (FOL; a phytopathogenic fungus). RESULTS: The mortality of BN seeds in the biosolarized soil was 12% higher than in the solarized soil, although this difference was not significant. However, a significant correlation between BN mortality and VFA accumulation was observed. The number of FOL colony-forming units (CFU) in solarized samples at 5 cm was 34 CFU g–1 of soil, whereas in the biosolarized samples levels were below the limit of quantification. At 15 cm, these levels were 100 CFU g–1 for solarized samples and < 50 CFU g–1 of soil for the biosolarized samples. Amendment addition positively affected the organic matter and potassium content after the solarization process. CONCLUSION: The organic waste stabilization method can impact downstream biosolarization performance and final pest inactivation levels. This study suggests that organic waste management practices can be leveraged to improve pest control and soil quality.

Managing high fiber food waste for the cultivation of black soldier fly larvae

Managing high fiber food waste for the cultivation of black soldier fly larvae Palma, Lydia; Fernández Bayo, Jesús Dionisio; Niemeier, Deb; Pitesky, Maurice; VanderGheynst, Jean S. Increases in global human population are leading to increasing demands for food production and waste management. Insect biomass is a sustainable alternative to traditional animal feeds when insects are produced on lignocellulosic by-products. Resources high in lignocellulose have high carbon to nitrogen ratios and require nitrogen supplementation to accelerate bioconversion. Here we report on studies that examine the influence of nitrogen supplementation of almond hull-based feedstocks on black soldier fly larvae (Hermetia illucens L.) cultivation and composition. Decreasing carbon to nitrogen ratio from 49 to 16 increased larvae harvest dry weight, specific larvae growth, and yield by 36%, 31%, and 51%, respectively. However, the decrease in carbon to nitrogen ratio decreased larvae methionine and cysteine contents by 11% and 13%, respectively. The findings demonstrate that carbon to nitrogen ratio can be managed to enhance bioconversion of lignocellulose to larvae, but that this management approach can reduce larvae amino acid content.

Sorption Characteristics of Chlordecone and Cadusafos in Tropical Agricultural Soils

Sorption Characteristics of Chlordecone and Cadusafos in Tropical Agricultural Soils Fernández Bayo, Jesús Dionisio; Saison, Carine; Geniez, Chantal; Voltz, Marc; Vereecken, Harry; Berns, Anne E. Banana plantations in tropical humid regions require a high input of pesticides. Given the long history of this practice, a number of pesticides that are now banned have accumulated in these soils. Little is known about the sorption of two banned insecticides, chlordecone and cadusafos, which are known to cause adverse environmental and health effects. We studied the sorption-desorption characteristics (Freundlich sorption-desorption coefficient, Kf, and partition coefficient, Kd) of these two molecules in tropical volcanic soils with different soil properties. In particular, we observed the effect of the chemical nature of the soil organic carbon (SOC). The sorption of chlordecone (35.56

Characterization of digestate microbial community structure following thermophilic anaerobic digestion with varying levels of green and food wastes

Characterization of digestate microbial community structure following thermophilic anaerobic digestion with varying levels of green and food wastes Fernández Bayo, Jesús Dionisio; Simmons, Christopher W.; VanderGheynst, Jean S. The properties of digestates generated through anaerobic digestion are influenced by interactions between the digester microbial communities, feedstock properties and digester operating conditions. This study investigated the effect of varying initial feedstock carbon to nitrogen (C/N) ratios on digestate microbiota and predicted abundance of genes encoding lignocellulolytic activity. The C/N ratio had a significant impact on the digestate microbiome. Feedstocks with intermediate C/N ratio (20–27) (where higher biomethane potential was observed) showed higher relative abundance of archaea compared to feedstocks with C/N ratios at 17 and 34. Within microbial networks, four microbial clusters and eight connector microorganisms changed significantly with the C/N ratio (P < 0.05). Feedstocks with C/N < 23 were richer in organisms from the family Thermotogaceae and genus Caldicoprobacter and enhanced potential for degradation of maltose, galactomannans, melobiose and lactose. This study provides new insights into how anaerobic digestion conditions relate to the structure and functional potential of digester microbial communities, which may be relevant to both digester performance and subsequent utilization of digestates for composting or amending soil. This work was funded by the UC Davis Sustainability Research and Training Program and Diamond Developers under collaboration identification number 201500317, and the National Institute of Food and Agriculture project CA-D-BAE-2228-RR. Sequencing was conducted by the Joint Genome Institute, which is supported by the Office of Science of the US Department of Energy [contract DE-AC02-05CH11231].