Effect of Salts Addition on Hydrogen Production by C. acetobutylicum

Abstract

The objective of this study is to investigate the effect of salts addition to fermentation medium on hydrogen production, under anaerobic batch culture system. In this study, batch experiments were conducted to investigate the inhibitory effect of both NaCl and sodium acetate on hydrogen production. The optimum pH and temperature for hydrogen production were at initial pH of 7.0 and 30 degrees C. Enhanced production of hydrogen, using glucose as substrate was achieved. In the absence of Sodium Chloride and Sodium Acetate enhanced hydrogen yield (Y(P/S)) from 350 mL g(-1) glucose utilized to 391 mL g(-1) glucose utilized with maximum hydrogen productivity of 77.5 ml/L/h. Results also show that sodium chloride and sodium acetate in the medium adversely affect growth. Hydrogen yield per biomass (Y(P/X)) of 254 ml/L/g, biomass per substrate utilized (Y(X/S)) of 0.268 and (Y(H2/S) of 0.0349. The results suggested that Sodium at any concentration resulted to inhibit the bacterial productivity of hydrogen.

Production of biosolvents and acids by salinity-adapted strain of clostridium acetobutylicum: Effects of salt and molasses concentrations

“…The adverse effects of salt on bacteria growth was reported by some other researchers. 11,12,14,15,27 These researchers declared that the ionic strength increased with increasing salt concentration and this caused higher osmotic pressures. In fact, when bacteria are exposed to higher osmolarity environments, the water exits from the cytoplasm and dehydration of cytoplasm or plasmolysis occurs.…”

“…In fact, when bacteria are exposed to higher osmolarity environments, the water exits from the cytoplasm and dehydration of cytoplasm or plasmolysis occurs. 11,12,14,15,25,26 Moreover, each bacterium needs a certain level of ions to activate enzymes and co-enzymes. As the amount of the ions is much greater than that required, chemical binding of the ions to enzymes arises.…”

“…As a result, the activities and structures of enzymes are disrupted. Therefore, high salinity results in reduction of bacterial growth, changes bacterial metabolic pathways and even can be inhibitor or toxic, 12,15,[25][26][27] In addition, McCarty and McKinney stated that cations, such as sodium, potas-sium, calcium and magnesium, play key roles in salt toxicity, since these cations affect anaerobic digestion. 26 The effects of pH variation for various salinities are shown in Fig.…”

“…However, with the rise in oil prices in the past few decades, 8 biofuels were introduced as a partial substitution of fossil fuels and to mitigate greenhouse gas emissions, 9 the industrial ABE process was restarted in recent years. 2,6,10 Some researchers have investigated the effect of salinity on Clostridium species [11][12][13] and other bacteria. 14,15 Alshiyab et al investigated the effects of salts, such as sodium chloride and sodium acetate, on hydrogen production using C. acetobutylicum NCIMB 13357.…”

“…They found that increasing the sodium chloride concentration from 0 to 5 g L -1 has an adverse effect on hydrogen productivity, biomass concentration and glucose consumption. 12 Rudyk and Søgaard studied the effect of salinity on the Clostridium tyrobutiricum strain. They showed that the strain could grow at 50 g L -1 salinity, however it was sensitive to greater salinities and hence, adapted the strain to 100 g L -1 salinity.…”