Q2. What future works have the authors mentioned in the paper "Bioaugmentation for improved recovery of anaerobic digesters after toxicant exposure" ?
In the future, the community structures of various digesters as well as bioaugmentation cultures should be determined and their response to bioaugmentation during toxicity events or periods of elevated propionate should be compared.
Q3. What was the PCR program used to identify the taxonomic classifications?
The SeqMatch program on the RDP website was used (Cole et al., 2007) to identify the taxonomic classifications if the 16S rRNA gene sequence similarity to known microorganisms was less than 95%.
Q4. What is the h2 concentration in anaerobic systems?
The H2 concentration in anaerobic systems must be very low (<50 mM) for conversion of propionate and other intermediates to methane to be thermodynamically spontaneous (McCarty and Smith, 1986).
Q5. What is the effect of bioaugmentation on the recovery of propionate?
The addition of H2 utilizers ostensibly reduced digester H2 concentration, resulting in more complete propionate degradation in MS systems.
Q6. What is the role of the bioaugmentation in the aerobic process?
Bioaugmentation of an aerobic processes has been reported toimprove degradation of specific organics, start-up of new digesters, odor reduction, and recovery of organically over-loaded systems at laboratory scale.
Q7. How many sequences were found in the methanosaeta genus?
Nine sequences grouped in the genus Methanosaeta (96% sequence similarity) and accounted for 21% of the Archaean sequences sampled.
Q8. How many mg/L of calcium acetate were used in the assay?
All assays were performed under anaerobic conditions in 160 mL serum bottles with 25 mL of enrichment culture having 100-400 mg/L VSS.
Q9. What is the reason for the failure of bioaugmentation applications?
Analysis of microbial communities in both bioaugmentation cultures and digester biomass is suggested to develop bioaugmentation applications.
Q10. What was the procedure used to remove vector sequences?
Vector sequences were removed using the Basic Local Alignment Search Tool (BLAST) to match vector sequences in the UniVec Database with the sample sequences in a manner identical to VecScreen (Altschul et al., 1997).
Q11. How long did the recovery period for the bioaugmented digesters last?
MS bioaugmented digesters achieved an SCOD concentration below 2 g/L over 80 days (i.e., 8 SRTs) before the controls (see Fig.5); in addition, the propionic acid concentrations in bioaugmented digesters declined below 200 mg/L approximately 70 days before that of the controls (Day 90 ± 0 versus Day 157 ± 18).
Q12. What was the PCR method used to analyze the sequences?
The forward and reverse sequences were analyzed using FinchTV (Geospira Inc., Seattle, WA) and Vector NTI (Invitrogen, Carlsbad, CA) and consensus sequences were assembled.
Q13. What was the effect of the bioaugmentation on the recovery of digesters?
A limited amount of the model toxicant, oxygen (O2), was added to different digesters for a short period, and recovery of bioaugmented and nonbioaugmented digesters was compared.