Changes in bacterial community during fermentative hydrogen and acid production from organic waste by thermophilic anaerobic microflora

Abstract

Aims: Changes in fermentation pattern during the treatment of organic wastes containing solid materials by thermophilic anaerobic microflora were investigated with respect to product formation and bacterial community structure during hydrogen production. Methods and Results: Anaerobic microflora enriched from sludge compost was cultivated using artificial garbage slurry in a continuous flow‐stirred tank reactor. Product formation varied depending on pH and hydraulic retention time (HRT) applied. Community analysis by terminal restriction fragment length polymorphism and clone library analysis of polymerase chain reaction‐amplified bacterial 16S rDNA indicated that difference in the fermentative product distribution could be caused by different populations of micro‐organisms in the microflora. Conclusion: Hydrogen fermentation with acetate/butyrate formation was optimized at <1·0 d HRT at pH 5·0 and 6·0. Thermoanaerobacterium thermosaccharolyticum was the dominant hydrogen‐producing micro‐organism. Conversely, unidentified organisms became dominant after 4·0 d HRT at pH 7·0 and 8·0, where relatively high‐solubilization efficiency of solid materials was observed with no production of hydrogen. Significance and Impact of the Study: This is the first report describing product formation in the fermentation of solid organic wastes by a mixed population of micro‐organisms. Various fermentation patterns including hydrogen fermentation were characterized and evaluated from engineering and microbial aspects.

Optimization of simultaneous thermophilic fermentative hydrogen production and COD reduction from palm oil mill effluent by Thermoanaerobacterium-rich sludge

“…In general, production of these two acids favors the production of hydrogen, according to Eqs. (5) and (6) [44]. Theoretically, four moles of hydrogen are produced from glucose concomitantly with 2 mol of acetate:…”

“…There have been many reports indicating that Thermoanaerobacterium spp. possess the capability to utilize complex carbohydrate such as starch, xylan, cracked corn, cellulose and simple sugar accompanied with hydrogen and acid production [41][42][43][44][45]. Several species of Thermoanaerobacterium are known for their hydrogen production characteristics, including T. thermosaccharolyticum, T. polysaccharolyticum, T. zeae, T. lactoethylicum and T. aotearoense.…”

Functional maintenance and structural flexibility of microbial communities perturbed by simulated intense rainfall in a pilot-scale membrane bioreactor

“…3), which indicates that there was a lag time to reestablish the microbial communities in response to the event ii. It has been reported that operational periods of at least threefold of the HRT are required for the turnover of the supplied wastewater (Ueno et al 2006. Taken together, the dynamics of the microbial diversity indices and finescale microbial community structure based on the weighted UniFrac distances were apparently correlated with the reactor performance, especially the COD removal ratio.…”

Long-term effect of acid and heat pretreatment of sludge from a sugarcane vinasse treatment plant on the microbial community and on thermophilic biohydrogen production

“…They have been identified as H 2 -producing bacteria in mixed cultures, under thermophilic conditions [9,47,48]. Several species of the genus Thermoanaerobacterium are known for their ability to produce H 2 , mainly T. saccharolyticum and T. thermosaccharolyticum [9,31].…”