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Metabolic engineering of Acinetobacter baylyi ADP1 for removal of Clostridium butyricum growth inhibitors produced from lignocellulosic hydrolysates.

Kannisto MS, Mangayil RK, Shrivastava-Bhattacharya A, Pletschke BI, Karp MT, Santala VP - Biotechnol Biofuels (2015)

Bottom Line: Pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars.Formate was consumed during growth on acetate and by stationary phase cells, and this was enhanced in the presence of a common aromatic inhibitor of lignocellulosic hydrolysates, 4-hydroxybenzoate.Because of these encouraging results, we believe that A. baylyi ADP1 is a promising candidate for the detoxification of lignocellulosic hydrolysates for bioprocesses.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland.

ABSTRACT

Background: Pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars. Selective inhibitor removal can be achieved with biodetoxification where microorganisms catabolize the inhibitors without consuming the sugars. We engineered the strictly aerobic Acinetobacter baylyi ADP1 for detoxification of lignocellulosic hydrolysates by removing the gene for glucose dehydrogenase, gcd, which catalyzes the first step in its glucose catabolism.

Results: The engineered A. baylyi ADP1 strain was shown to be incapable of consuming the main sugar components of lignocellulosic hydrolysates, i.e., glucose, xylose, and arabinose, but rapidly utilized acetate and formate. Formate was consumed during growth on acetate and by stationary phase cells, and this was enhanced in the presence of a common aromatic inhibitor of lignocellulosic hydrolysates, 4-hydroxybenzoate. The engineered strain tolerated glucose well up to 70 g/l, and the consumption of glucose, xylose, or arabinose was not observed in prolonged cultivations. The engineered strain was applied in removal of oxygen, a gaseous inhibitor of anaerobic fermentations. Co-cultivation with the A. baylyi ADP1 gcd knockout strain under initially aerobic conditions allowed the strictly anaerobic Clostridium butyricum to grow and produce hydrogen (H2) from sugars of the enzymatic rice straw hydrolysate.

Conclusions: We demonstrated that the model organism of bacterial genetics and metabolism, A. baylyi ADP1, could be engineered to be an efficient biodetoxification strain of lignocellulosic hydrolysates. Only one gene knockout was required to completely eliminate sugar consumption and the strain could be used in production of anaerobic conditions for the strictly anaerobic hydrogen producer, C. butyricum. Because of these encouraging results, we believe that A. baylyi ADP1 is a promising candidate for the detoxification of lignocellulosic hydrolysates for bioprocesses.

No MeSH data available.


Related in: MedlinePlus

A. baylyi ADP1 gcd knockout strain’s relative growth on 4 g/l acetate at different d-glucose concentrations after 24 h of cultivation. Relative growth values were calculated by dividing the optical densities by an average optical density value at 0 g/l d-glucose. The data are averages from triplicate cultivations with error bars representing standard deviations
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Fig3: A. baylyi ADP1 gcd knockout strain’s relative growth on 4 g/l acetate at different d-glucose concentrations after 24 h of cultivation. Relative growth values were calculated by dividing the optical densities by an average optical density value at 0 g/l d-glucose. The data are averages from triplicate cultivations with error bars representing standard deviations

Mentions: As glucose concentration in lignocellulosic hydrolysates varies greatly depending on the source and pretreatment of the biomass, we tested the ability of the gcd knockout strain to grow on 4 g/l acetate at glucose concentrations from 0 to 200 g/l (Fig. 3). The presence of the sugar in the medium, at concentrations below 70 g/l, inhibited growth only to a very modest degree. Increasing the glucose concentration above this level began to affect growth to a much greater extent, although the cells grew even at glucose concentration of 150 g/l. Thus it seems that high concentration of glucose, usually the most abundant sugar in lignocellulosic hydrolysates, should not become detrimental to the growth of A. baylyi ADP1 gcd knockout mutant.Fig. 3


Metabolic engineering of Acinetobacter baylyi ADP1 for removal of Clostridium butyricum growth inhibitors produced from lignocellulosic hydrolysates.

Kannisto MS, Mangayil RK, Shrivastava-Bhattacharya A, Pletschke BI, Karp MT, Santala VP - Biotechnol Biofuels (2015)

A. baylyi ADP1 gcd knockout strain’s relative growth on 4 g/l acetate at different d-glucose concentrations after 24 h of cultivation. Relative growth values were calculated by dividing the optical densities by an average optical density value at 0 g/l d-glucose. The data are averages from triplicate cultivations with error bars representing standard deviations
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4666034&req=5

Fig3: A. baylyi ADP1 gcd knockout strain’s relative growth on 4 g/l acetate at different d-glucose concentrations after 24 h of cultivation. Relative growth values were calculated by dividing the optical densities by an average optical density value at 0 g/l d-glucose. The data are averages from triplicate cultivations with error bars representing standard deviations
Mentions: As glucose concentration in lignocellulosic hydrolysates varies greatly depending on the source and pretreatment of the biomass, we tested the ability of the gcd knockout strain to grow on 4 g/l acetate at glucose concentrations from 0 to 200 g/l (Fig. 3). The presence of the sugar in the medium, at concentrations below 70 g/l, inhibited growth only to a very modest degree. Increasing the glucose concentration above this level began to affect growth to a much greater extent, although the cells grew even at glucose concentration of 150 g/l. Thus it seems that high concentration of glucose, usually the most abundant sugar in lignocellulosic hydrolysates, should not become detrimental to the growth of A. baylyi ADP1 gcd knockout mutant.Fig. 3

Bottom Line: Pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars.Formate was consumed during growth on acetate and by stationary phase cells, and this was enhanced in the presence of a common aromatic inhibitor of lignocellulosic hydrolysates, 4-hydroxybenzoate.Because of these encouraging results, we believe that A. baylyi ADP1 is a promising candidate for the detoxification of lignocellulosic hydrolysates for bioprocesses.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland.

ABSTRACT

Background: Pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars. Selective inhibitor removal can be achieved with biodetoxification where microorganisms catabolize the inhibitors without consuming the sugars. We engineered the strictly aerobic Acinetobacter baylyi ADP1 for detoxification of lignocellulosic hydrolysates by removing the gene for glucose dehydrogenase, gcd, which catalyzes the first step in its glucose catabolism.

Results: The engineered A. baylyi ADP1 strain was shown to be incapable of consuming the main sugar components of lignocellulosic hydrolysates, i.e., glucose, xylose, and arabinose, but rapidly utilized acetate and formate. Formate was consumed during growth on acetate and by stationary phase cells, and this was enhanced in the presence of a common aromatic inhibitor of lignocellulosic hydrolysates, 4-hydroxybenzoate. The engineered strain tolerated glucose well up to 70 g/l, and the consumption of glucose, xylose, or arabinose was not observed in prolonged cultivations. The engineered strain was applied in removal of oxygen, a gaseous inhibitor of anaerobic fermentations. Co-cultivation with the A. baylyi ADP1 gcd knockout strain under initially aerobic conditions allowed the strictly anaerobic Clostridium butyricum to grow and produce hydrogen (H2) from sugars of the enzymatic rice straw hydrolysate.

Conclusions: We demonstrated that the model organism of bacterial genetics and metabolism, A. baylyi ADP1, could be engineered to be an efficient biodetoxification strain of lignocellulosic hydrolysates. Only one gene knockout was required to completely eliminate sugar consumption and the strain could be used in production of anaerobic conditions for the strictly anaerobic hydrogen producer, C. butyricum. Because of these encouraging results, we believe that A. baylyi ADP1 is a promising candidate for the detoxification of lignocellulosic hydrolysates for bioprocesses.

No MeSH data available.


Related in: MedlinePlus