Influence of External pH and Fermentation Products on
            <i>Clostridium acetobutylicum</i>
            Intracellular pH and Cellular Distribution of Fermentation Products

Huang, Li; Forsberg, Cecil W.; Gibbins, L. N.

doi:10.1128/aem.51.6.1230-1234.1986

Cited by 92 publications

(33 citation statements)

References 13 publications

(26 reference statements)

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“…Thus, a reduction of the extracellular pH by only 0.3 units, which would, in turn, cause a reduction of the intracellular pH from 5.4 to 5.1, may have caused the inhibition of solventogenesis. Butanol has been shown to decrease the ApH in C. acetobutylicum (3,6,11,21). Decanol may cause the same effect because linear alcohols often have similar effects, differing only in potency, in biological systems (12).…”

Section: Discussionmentioning

confidence: 99%

Enhancement of Butanol Formation by Clostridium acetobutylicum in the Presence of Decanol-Oleyl Alcohol Mixed Extractants

Evans

Wang

1988

Appl Environ Microbiol

106

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Extractive fermentation has been proposed to enhance the productivity of fermentations that are end product inhibited. Unfortunately, good extractants for butanol, such as decanol, are toxic to Clostridium acetobutylicum. The use of mixed extractants, namely, mixtures of toxic and nontoxic coextractants, was proposed to circumvent this toxicity. Decanol appeared to inhibit butanol formation by C. acetobutylicum when present in a mixed extractant that also contained oleyl alcohol. However, maintenance of the pH at 4.5 alleviated the inhibition of butanol production and the consumption of butyrate during solventogenesis. A mixed extractant that contained 20% decanol in oleyl alcohol enhanced butanol formation by 72% under pH-controlled conditions. The production of acetone and acetoin was also increased, even though these two products were not extractable. The enhancement of butanol formation was not limited by the toxicity of decanol. Supplementation of glucose and butyrate in the extractive fermentation yielded a 47% increase in butanol. The enhancement of butanol formation appeared to be dependent on the presence of dissolved decanol in the broth but was not observed unless an organic phase was present to extract butanol. A mechanism for the effects of decanol on product formation is proposed. Batch fermentation by Clostridium acetobutylicum is characterized by two phases. During the first phase, or acidogenesis, C. acetobutylicum grows and produces acetate and butyrate from glucose. These acids attain their maximal concentrations and are consumed in the second phase, which is known as solventogenesis. The acids are reduced, and neutral solvents including butanol, acetone, ethanol, and acetoin are produced. Butanol is generally produced in concentrations of no greater than 12 g/liter (17, 23). This limitation is thought to be due to the toxicity of butanol to C. acetobutylicum (9, 14, 17). One technique for increasing butanol production is genetic alteration of C. acetobutylicum to make it more tolerant to butanol. A number of attempts have been made in this regard with varying degrees of success (9, 16, 17). How much

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Section: Discussionmentioning

confidence: 99%

Enhancement of Butanol Formation by Clostridium acetobutylicum in the Presence of Decanol-Oleyl Alcohol Mixed Extractants

Evans

Wang

1988

Appl Environ Microbiol

106

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“…The build up of acidic products, particularly acetic acid, eventually inhibits further growth of anaerobic cultures, probably by acting as a weak uncoupler [92]. At pH 4.5 the level of acetate inside the cell is several times its external concentration, at least in Clostridia [93]. These observations have been used as the basis for a selection procedure which kills acid-excreting cells [94].…”

Section: Ch3co-scoa + Pi ~ Ch3co-p + Coashmentioning

confidence: 99%

The fermentation pathways of Escherichia coli

Clark¹

1989

FEMS Microbiology Reviews

351

240

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Under anaerobic conditions and in the absence of alternative electron acceptors Escherichia coli converts sugars to a mixture of products by fermentation. The major soluble products are acetate, ethanol, acetate and formate with smaller amounts of succinate. In addition the gaseous products hydrogen and carbon dioxide are produced in substantial amounts. The pathway generating fermentation products is branched and the flow down each branch is varied in response both to the pH of the culture medium and the nature of the fermentation substrate. In particular, the ratio of the various fermentation products is manipulated in order to balance the number of reducing equivalents generated during glycolytic breakdown of the substrate. The enzymes and corresponding genes involved in these fermentation pathways are described. The regulatory responses of these genes and enzymes are known but the details of the underlying regulatory mechanisms are still obscure.

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“…The compounds highlighted in bold are those that are antibacterial. As can be observed from (Hamak, 2015;Huang, Forsberg, & Gibbins, 1986;Jain, Ravichandran, Sisodiya, & Agrawal, 2010;Lu et al, 2012;Ramachandran, Rani, Senthan, Jeong, & Kabilan, 2011;Seanego & Ndip, 2012;Sikkema, de Bont, & Poolman, 1995;Vijesh, Isloor, Telkar, Peethambar, & Rai, 2011). It was observed that, the decanoic fractions were highest in case of Soy BA (Figure 7c), followed by Soy A, which was the exact sequence of antibacterial activity observed.…”

Section: Gc-ms Analysis Of Extracts For Antimicrobial Compoundsmentioning

confidence: 65%

Synergistic bacterio-myco soyabean co-fermentation methodology for harnessing the unexhausted

Gopal

Chun

et al. 2017

J Food Process Preserv

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Fermented soya arrived as an attractive option to do away with the unwanted and goitrogenic aspects of soyabeans. Fermentation of soybean with its fancy limited to Asian countries is still poorly understood in terms of its fermentation system. In this work a synergistic methodology of myco‐bacterio co‐fermentation, for enhancing the bioactive components in the end product was optimized. Systematic combinations of fungi and bacteria and their fermented products were tested for their total phenolic contents and respective antioxidant and antibacterial properties. The results support that a bacterio‐mold (myco) based synergistic fermentation is recommended. Synergistic Bacillus initiated co‐fermentation led to extraction of effective antibacterial compounds. GC‐MS results indicate the presence of antibacterial components such as imidazole, hexadecanoic acid, octadecanoic acid, methyl‐7‐dodecen‐1‐ol acetate, piperidinone, furan derivatives, and xylitol. Of these the decanoic fractions are speculated to play a predominating role in the antimicrobial activity. Practical applications A synergistic co‐fermentation methodology for extraction of antimicrobial compounds was optimized. For the first time we report the benefit from bacterial and fungal co‐fermentation and confirm the importance of the sequence of the inoculation order too. Successful water based extraction achieved via this method as confirmed by the GC‐MS validation. With the ever increasing need for proteins this methodology will aid in harnessing the best reserves caged inside soybeans.

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Influence of External pH and Fermentation Products on Clostridium acetobutylicum Intracellular pH and Cellular Distribution of Fermentation Products

Cited by 92 publications

References 13 publications

Enhancement of Butanol Formation by Clostridium acetobutylicum in the Presence of Decanol-Oleyl Alcohol Mixed Extractants

Enhancement of Butanol Formation by Clostridium acetobutylicum in the Presence of Decanol-Oleyl Alcohol Mixed Extractants

The fermentation pathways of Escherichia coli

Synergistic bacterio-myco soyabean co-fermentation methodology for harnessing the unexhausted

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