Different types of H 2 photoproduction by starch-utilizing co-cultures of Clostridium butyricum and Rhodobacter sphaeroides

Advances and Applications of Clostridium Co-culture Systems in Biotechnology

“…At the same time, Laurinavichene and Tsygankov (2015) observed the inhibition of Clostridium by purple bacteria in which the purple bacteria could consume hydrogen produced by C. butyricum at early phase, thus reducing the hydrogen yield. Further, they found hydrogen production by C. butyricum in co-culture with Rhodobacter sphaeroides N7 was retarded as compared to the mono-culture after 3 days ( Laurinavichene and Tsygankov, 2015 ) and confirmed that a high yeast extract concentration (160–320 mg/L) enhanced reliable H 2 production ( Laurinavichene and Tsygankov, 2016 ; Laurinavichene et al, 2016 ). They used a repeated batch photofermentation utilizing starch with co-culture of C. butyricum and R. sphaeroides N7 over 15 months to obtain efficient H 2 production with an average H 2 yield of 5.2 mol/mol glucose with no accumulation of organic acids in the presence of Clostridia ( Laurinavichene et al, 2018 ).…”

“…They found that the hydrogen production decreased gradually with sucrose concentration increasing from 4.45 g/L to 35.6 g/L, and the maximum hydrogen production of 5.42 mol/mol sucrose was acquired at 4.45 g/L sucrose, which showed high sucrose concentrations inhibited hydrogen production ( Kao et al, 2016b ). At the same time, the concentration of yeast extract has also been shown to have a significant effect on hydrogen production in co-culture of C. butyricum and R. sphaeroides ( Laurinavichene and Tsygankov, 2016 ; Laurinavichene et al, 2016 ). In most cases, the co-culture medium contained growth factors necessary for the normal growth and metabolism of the two bacteria, or metal ions, trace elements and vitamins etc., in addition to different substrates, to maintain the stability of the co-culture and the performance of the fermented products ( Ding et al, 2009 ).…”

“…Eventually pH 7 was determined to be the best condition for bacterial cooperation during a combined process to produce hydrogen through optimization of a co-culture of solventogenic Clostridia and anoxygenic phototrophic bacteria ( Zagrodnik and Laniecki, 2015 ). In addition, adjustment of the phosphate buffer concentration ( Laurinavichene and Tsygankov, 2016 ), adopting a fixed pH value ( Zagrodnik and Laniecki, 2015 ), and addition of exogenous regulators such as eggshell biowaste ( Pachapur et al, 2016a ) were also shown to be good pH control strategies in many Clostridium co-culture systems. Moreover, co-culture of immobilized cells will be less affected by changes in medium pH and thus promote system stability and yield, which is also considered a good strategy ( Xu and Tschirner, 2014 ).…”