High production of 2,3-butanediol from glycerol by Klebsiella pneumoniae G31

Abstract

The microbial production of high amounts of 2,3-butanediol (2,3-BD) from glycerol as a sole carbon source by the Bulgarian isolate Klebsiella pneumoniae G31 was studied in a series of fed-batch processes. The following conditions were evaluated as optimal: micro-aerobic cultivation in modified media, without pH control. Beginning at pH 8, 49.2 g/l of 2,3-BD was produced as negligible concentrations of by-products were received. The pH is the most important factor ruling the 2,3-BD production. Spontaneous pH changes and products formation in time were investigated, performing fermentations with non-controlled pH starting at different initial pH. In lack of external maintenance, the microorganism attempted to control the pH using acetate/2,3-BD alternations of the oxidative pathway of glycerol catabolism, which resulted in pH fluctuations. Thus, the culture secreted 2,3-BD at unequal portions, either allowing or detaining the acetate synthesis. More alkaline initial pH led to enhanced 2,3-BD accumulation as a response to the increased amplitudes of the pH variations. When the pH was maintained constant, the yield of 2,3-BD was very poor. These cultures remained viable only 72 h; whereas, the pH self-controlling cells lived and produced 2,3-BD up to 280 h. In conclusion, the formation of 2,3-BD is a result of an adaptive mechanism of pH self-control, responding to spontaneous pH drops during glycerol fermentation.

Glycerol Dehydrogenase Plays a Dual Role in Glycerol Metabolism and 2,3-Butanediol Formation in Klebsiella pneumoniae

“…The promiscuity of DhaD may also contribute to the prevention of acidification by shifting glycerol metabolism from acid production to the formation of neutral compounds. This hypothesis is supported by the fact that BD production from glycerol is responsive to spontaneous pH drops during glycerol metabolism and can be increased by forced pH fluctuations (9,47). Additionally, as an intestinal bacterium, K. pneumoniae could utilize the glycerol that is decomposed from triglyceride in the intestinal tract.…”

Use of Glycerol in Biotechnological Applications

“…Production of 2,3-BDO from glycerol by K. pneumoniae G31 resulted in final concentrations of 49.2 g l -1 . The medium pH had a large influence on 2,3-BDO fermentation from glycerol with 2,3-BDO production being favored at alkaline pH (Petrov & Petrova, 2009). In addition, intense aeration increased 2,3-BDO synthesis and reduced byproducts (Petrov & Petrova, 2010).…”

Produção de celulases por fungos de ambiente marinho e terrestre para uso na hidrólise do bagaço de cana-de-açúcar e produção de 2,3-butanodiol pela bactéria <i>Serratia marcescens</i> a partir de glicose e glicerol

“…Além de ser um substrato de baixo custo, o uso do glicerol na produção de 2,3-butanodiol é vantajoso, pois é um subproduto na produção de biodiesel, cuja massa do glicerol corresponde a 10% da massa do biodiesel produzida (PETROV & PETROVA, 2009;DA SILVA et al, 2009). No entanto, o 2,3-butanodiol não é, na maioria dos trabalhos publicados, o principal produto da fermentação do glicerol, sendo o produto secundário, tendo como produto majoritário o 1,3-propanodiol (OH et al, 2013;DE SOUZA et al, 2014;YEN et al, 2014a).…”

“…Um exemplo de aumento na produção de 2,3-butanodiol a partir de glicerol foi descrito por Petrov & Petrova (2009) Outros trabalhos relataram mudanças na concentração dos produtos da fermentação do glicerol através de alterações do pH do meio cultivo, reforçando a sua importância para o processo (BIEBL et al, 1998;YEN et al, 2014).…”

“…2,3-Butanodiol é um reagente químico promissor e que possui inúmeras aplicações industriais, tais como, na produção de cosméticos, de alimentos, de medicamentos, de polímeros, fumigantes, explosivos e de soluções anticongelantes; além de ser usado na síntese de produtos químicos como blocos de construção (PETROV & PETROVA, 2009;KIM et al, 2014;CELINSKA & GRAJEK, 2009;HU et al, 2016 SABRA et al, 2011;JI et al, 2011).…”