Bacterial Population Dynamics in Dairy Waste during Aerobic and Anaerobic Treatment and Subsequent Storage

Abstract

The objective of this study was to model a typical dairy waste stream, monitor the chemical and bacterial population dynamics that occur during aerobic or anaerobic treatment and subsequent storage in a simulated lagoon, and compare them to those of waste held without treatment in a simulated lagoon. Both aerobic and anaerobic treatment methods followed by storage effectively reduced the levels of total solids (59 to 68%), biological oxygen demand (85 to 90%), and sulfate (56 to 65%), as well as aerobic (83 to 95%), anaerobic (80 to 90%), and coliform (>99%) bacteria. However, only aerobic treatment reduced the levels of ammonia, and anaerobic treatment was more effective at reducing total sulfur and sulfate. The bacterial population structure of waste before and after treatment was monitored using 16S rRNA gene sequence libraries. Both treatments had unique effects on the bacterial population structure of waste. Aerobic treatment resulted in the greatest change in the type of bacteria present, with the levels of eight out of nine phyla being significantly altered. The most notable differences were the >16-fold increase in the phylum Proteobacteria and the approximately 8-fold decrease in the phylum Firmicutes. Anaerobic treatment resulted in fewer alterations, but significant decreases in the phyla Actinobacteria and Bacteroidetes, and increases in the phyla Planctomycetes, Spirochetes, and TM7 were observed.

Seasonal Variation on Microbial Community and Methane Production during Anaerobic Digestion of Cattle Manure in Brazil

“…The dominance of these phyla in biogas reactors is in agreement with other community analyses in anaerobic bioreactors [21,23,28,29]. In this study, within the phylum Firmicutes, class Clostridia dominated in the bacterial community.…”

Microbial Diversity and Host-Specific Sequences of Canada Goose Feces

“…The T. sanguinis assays showed cross-amplification with pig, cow, chicken, and human (sewage) feces, suggesting that these assays may not be useful in tracking specific fecal sources. Originally isolated from the blood of a febrile patient with acute appendicitis (3), T. sanguinis has also been found in the insect gut (12,33), dairy waste (28), and cheese and milk samples (6). However, the results from this study suggest that T. sanguinis is more ubiquitous in the animal gut than previously known.…”

Longitudinal Characterization of Resistant Escherichia coli in Fecal Deposits from Cattle Fed Subtherapeutic Levels of Antimicrobials

“…The delayed growth in our study may have resulted from the low environmental temperatures at the beginning of the experiment, given that growth of E. coli occurred when the maximum daily temperature ranged between 14°C and 21°C. It is also possible that E. coli growth was partially attributable to reductions in competing bacteria as oxygen penetrated the feces with time (34). This may have reduced numbers of obligate anaerobes, perhaps changing the niche to one more favorable for E. coli.…”