Accurate biochemical methane potential (BMP) tests are essential to find new, efficient substrates and optimize existing processes to get higher quantity and better-quality biogas. Even if consistent protocols exist, the major bottleneck in this research is the lack of a ready-to-use, standardized methanogenic culture inoculum. The cause is the slow growth of microorganisms in anaerobic conditions and the high cost of maintaining them active in the necessary amount. This study considers two preservation strategies: freezing at -20°C with addition of DMSO as cryoprotectant and the use of agar gel as preservation carrier stored at 20°C. The results of the BMP test after storage indicates that agar gel represents the most efficient preservation strategy, but also reveals that agar is consumed by microorganisms as substrates even during the storage period. DMSO has a detrimental effect on the samples as it turns out to have high toxicity at incubation temperature. To investigate the effect of DMSO, a further experiment was set up. The samples were stored for one night at -20°C degrees with the addition of DMSO. The following day in half of the samples it was removed by centrifugation, in the other half it was left. Finally, a BMP test was performed and showed that removal of DMSO through centrifugation enhances the revival, but the inoculum doesn’t reach its usual methane production
Laboratory studies on the preservation of inocula for BMP testing
SCALZOTTO, BENEDETTA
2021/2022
Abstract
Accurate biochemical methane potential (BMP) tests are essential to find new, efficient substrates and optimize existing processes to get higher quantity and better-quality biogas. Even if consistent protocols exist, the major bottleneck in this research is the lack of a ready-to-use, standardized methanogenic culture inoculum. The cause is the slow growth of microorganisms in anaerobic conditions and the high cost of maintaining them active in the necessary amount. This study considers two preservation strategies: freezing at -20°C with addition of DMSO as cryoprotectant and the use of agar gel as preservation carrier stored at 20°C. The results of the BMP test after storage indicates that agar gel represents the most efficient preservation strategy, but also reveals that agar is consumed by microorganisms as substrates even during the storage period. DMSO has a detrimental effect on the samples as it turns out to have high toxicity at incubation temperature. To investigate the effect of DMSO, a further experiment was set up. The samples were stored for one night at -20°C degrees with the addition of DMSO. The following day in half of the samples it was removed by centrifugation, in the other half it was left. Finally, a BMP test was performed and showed that removal of DMSO through centrifugation enhances the revival, but the inoculum doesn’t reach its usual methane productionFile | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/29602