Clostridium kluyverii, an Organism Concerned in the Formation of Caproic Acid from Ethyl Alcohol

Abstract

When ethyl alcohol is acted upon by the methane-producing organism, Methanobacterium omelianskii, acetic acid is the sole oxidation product (Barker (1939-40, 1941)). But with alcoholcontaining enrichment cultures for the same organism it often happens that acetic acid is formed in only relatively small amounts, while most of the alcohol is converted into caproic and butyric acids (Barker (1937)). In some cultures as much as 75 per cent by weight of the volatile acid is caproic. Microscopic examination has shown that such caproic-acidproducing enrichment cultures always differ from those forming only acetic acid by containing, besides M. omelianskii, considerable numbers of a large, motile, spore-forming bacterium. The conclusion seemed justified that this latter organism either itself produces or at least helps to produce the caproic acid. However, direct proof of the participation of the spore-forming bacterium in caproic acid formation can be obtained only by studying the organism in pure culture. This communication describes the isolation, the general morphological and physiological characteristics and certain growtlh requirements of this bacterium. Also, evidence is presented which demonstrates that it is responsible for the conversion of ethyl alcohol to caproic acid. Enrichment and isolation. To obtain the caproic acid-producing organism, Clostridium kluyverii,1 the following enrichment medium (no. 1) made with tap water is used: C2H5OH 1 vol. per cent; K2HPO4 0.5 per cent; MgSO4 7H20 0.01 per cent; (NH4)2 SO4 0.03 per cent; FeSO4 .77H20 0.002 per cent; yeast autolysate 0.5 Justification foi the uise of this name is given in a later section of this paper.

Characterization of Prokaryotic Community Diversity in New and Aged Pit Muds from Chinese <i>Luzhou</i>-flavor Liquor Distillery

“…Tissierella produces acetic, butyric, isovaleric acids (Vos et al, 2009). C. kluyveri produces caproic acid (Barker and Taha, 1942;Weimer and Stevenson, 2012) Streptococcus in new pit muds were higher than these in aged pit muds. The reduction of these three genera resulted in the reduction of lactic acid and ethyl lactate in aged pit muds.…”

Enrichment and characterisation of ethanol chain elongating communities from natural and engineered environments

“…This stepwise two-carbon increase of the carboxylic acid acyl-chain is why this metabolism is often named chain elongation. Clostridium kluyveri was the first isolated bacterium capable of producing caproic acid and since then it has been thoroughly investigated, mostly focusing on its unique metabolism [10][11][12][13] .In what concerns the engineering of caproic acid bio-production, most studies have used open communities because they can offer several advantages over axenic cultures: (i) no need for sterility, as the community is functionally stabilized by the operational conditions; (ii) increased process stability under changing conditions, i.e. present but inactive species can take over the role of failing organisms, so-called functional redundancy in open ) in the specific case of chain elongation for production of caproic acid, open communities have been shown to outperform the pure culture C. kluyveri 15 .…”

“…This stepwise two-carbon increase of the carboxylic acid acyl-chain is why this metabolism is often named chain elongation. Clostridium kluyveri was the first isolated bacterium capable of producing caproic acid and since then it has been thoroughly investigated, mostly focusing on its unique metabolism [10][11][12][13] .…”

Use of microbial indicators combined with environmental factors coupled with metrology tools for discrimination and classification ofLuzhou-flavoured pit muds

“…Copy numbers of C. kluyveri in aged pit mud are reportedly higher than those in new pit mud (Hu et al 2015;Zhang et al 2017a, b), which we also observed. C. kluyveri can produce caproic acid (Barker and Taha 1942;Weimer and Stevenson 2012), which is the precursor for ethyl caproate, the typical flavour compound of Luzhou-flavoured liquor. Some trends in microbial indicators and environmental factors varied in new and aged pit mud.…”