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Improved biomass and protein production in solid-state cultures of an Aspergillus sojae strain harboring the Vitreoscilla hemoglobin.

Mora-Lugo R, Madrigal M, Yelemane V, Fernandez-Lahore M - Appl. Microbiol. Biotechnol. (2015)

Bottom Line: In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt).No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions.Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.

View Article: PubMed Central - PubMed

Affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. r.moralugo@jacobs-university.de.

ABSTRACT
The biotechnological value of Aspergillus sojae ATCC 20235 (A. sojae) for production of pectinases in solid-state fermentation (SSF) has been demonstrated recently. However, a common drawback of fungal solid-state cultures is the poor diffusion of oxygen into the fungi that limits its growth and biological productivity. The bacterial Vitreoscilla hemoglobin (VHb) has favored the metabolism and productivities of various bacterial and yeast strains besides alleviating hypoxic conditions of its native host, but the use of VHb in filamentous fungi still remains poor explored. Based on the known effects of VHb, this study assessed its applicability to improve A. sojae performance in SSF. The VHb gene (vgb) under control of the constitutive Aspergillus nidulants gpdA promoter was introduced into the genome of A. sojae by Agrobacterium-mediated transformation. Successful fungal transformants were identified by fluorescence microscopy and polymerase chain reaction (PCR) analyses. In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt). Similarly, biomass content was also 1.3 times higher in the transformant strain. No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions. Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.

No MeSH data available.


Related in: MedlinePlus

Protein production of A. sojae wt and A. sojae vgb + in SSF. Exo-PG (a), exo-PMG (b), endo-PG (c), and protease (d) content were determined from enzymatic extracts collected every 24 h during the 10-day incubation period. Solid lines indicate the enzymatic yield, and dashed lines indicate specific activity. Each data point represents the average ± SD from fermentations carried out in triplicates
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Fig4: Protein production of A. sojae wt and A. sojae vgb + in SSF. Exo-PG (a), exo-PMG (b), endo-PG (c), and protease (d) content were determined from enzymatic extracts collected every 24 h during the 10-day incubation period. Solid lines indicate the enzymatic yield, and dashed lines indicate specific activity. Each data point represents the average ± SD from fermentations carried out in triplicates

Mentions: To evaluate whether VHb had a positive effect on the production of extracellular proteins of A. sojae in SSF, fermented samples of the transformant A. sojae vgb + and parental A. sojae wt strain were harvested daily and assessed for various enzymatic activities. A clear difference in protein production was observed between both fungal strains (Fig. 4). Regarding to pectinase production, the maximum exo-PG and exo-PMG titers of 562.1 and 75.4 U/g after 7 days of fermentation with A. sojae vgb + were nearly 1.60-fold and 1.45-fold higher, respectively, in comparison to the wild-type strain (Fig. 4a–b). However, no relative increase of endo-PG content was measured in the recombinant fungus, compared to the wild-type strain. In this case, the maximum endo-PG titer of 132.1 U/g was observed for the wild-type strain after 6 days of fermentation (Fig. 4c). Regarding protease production, the maximum quantity of 39.2 U/g was nearly 1.25-fold higher in the transformed fungus compared to the parental strain after 6 days of fermentation (Fig. 4d). Overall, the maximum enzymatic titers for both fungal strains were between the sixth and seventh day of fermentation. The pH of all enzymatic extracts increased overtime ranging from pH 3.9 ± 0.3 at the start to pH 5.8 ± 0.5 at the end of the fermentation, in both the transformant and wild-type strains.Fig. 4


Improved biomass and protein production in solid-state cultures of an Aspergillus sojae strain harboring the Vitreoscilla hemoglobin.

Mora-Lugo R, Madrigal M, Yelemane V, Fernandez-Lahore M - Appl. Microbiol. Biotechnol. (2015)

Protein production of A. sojae wt and A. sojae vgb + in SSF. Exo-PG (a), exo-PMG (b), endo-PG (c), and protease (d) content were determined from enzymatic extracts collected every 24 h during the 10-day incubation period. Solid lines indicate the enzymatic yield, and dashed lines indicate specific activity. Each data point represents the average ± SD from fermentations carried out in triplicates
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4628083&req=5

Fig4: Protein production of A. sojae wt and A. sojae vgb + in SSF. Exo-PG (a), exo-PMG (b), endo-PG (c), and protease (d) content were determined from enzymatic extracts collected every 24 h during the 10-day incubation period. Solid lines indicate the enzymatic yield, and dashed lines indicate specific activity. Each data point represents the average ± SD from fermentations carried out in triplicates
Mentions: To evaluate whether VHb had a positive effect on the production of extracellular proteins of A. sojae in SSF, fermented samples of the transformant A. sojae vgb + and parental A. sojae wt strain were harvested daily and assessed for various enzymatic activities. A clear difference in protein production was observed between both fungal strains (Fig. 4). Regarding to pectinase production, the maximum exo-PG and exo-PMG titers of 562.1 and 75.4 U/g after 7 days of fermentation with A. sojae vgb + were nearly 1.60-fold and 1.45-fold higher, respectively, in comparison to the wild-type strain (Fig. 4a–b). However, no relative increase of endo-PG content was measured in the recombinant fungus, compared to the wild-type strain. In this case, the maximum endo-PG titer of 132.1 U/g was observed for the wild-type strain after 6 days of fermentation (Fig. 4c). Regarding protease production, the maximum quantity of 39.2 U/g was nearly 1.25-fold higher in the transformed fungus compared to the parental strain after 6 days of fermentation (Fig. 4d). Overall, the maximum enzymatic titers for both fungal strains were between the sixth and seventh day of fermentation. The pH of all enzymatic extracts increased overtime ranging from pH 3.9 ± 0.3 at the start to pH 5.8 ± 0.5 at the end of the fermentation, in both the transformant and wild-type strains.Fig. 4

Bottom Line: In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt).No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions.Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.

View Article: PubMed Central - PubMed

Affiliation: Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. r.moralugo@jacobs-university.de.

ABSTRACT
The biotechnological value of Aspergillus sojae ATCC 20235 (A. sojae) for production of pectinases in solid-state fermentation (SSF) has been demonstrated recently. However, a common drawback of fungal solid-state cultures is the poor diffusion of oxygen into the fungi that limits its growth and biological productivity. The bacterial Vitreoscilla hemoglobin (VHb) has favored the metabolism and productivities of various bacterial and yeast strains besides alleviating hypoxic conditions of its native host, but the use of VHb in filamentous fungi still remains poor explored. Based on the known effects of VHb, this study assessed its applicability to improve A. sojae performance in SSF. The VHb gene (vgb) under control of the constitutive Aspergillus nidulants gpdA promoter was introduced into the genome of A. sojae by Agrobacterium-mediated transformation. Successful fungal transformants were identified by fluorescence microscopy and polymerase chain reaction (PCR) analyses. In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt). Similarly, biomass content was also 1.3 times higher in the transformant strain. No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions. Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.

No MeSH data available.


Related in: MedlinePlus