This paper investigates Aspergillus niger's behaviour in the presence of mobile Al3+ species by evaluating the changes in oxalate exudation at various aluminium contents. When the fungus was exposed to Al3+, no significant changes in oxalate production were observed until 100 mg.L-1 aluminium was reached resulting in oxalate production decrease by 18.2%. By stripping the culture medium completely of phosphate, even more prominent decrease by 34.8% and 67.1% at 10 and 100 mg.L-1 aluminium was observed, respectively, indicating the phosphate's significance instead of Al3+ in oxalate production. Our results suggest that the low phosphate bioavailability, which most likely resulted from its interaction with Al3+, stimulated the overproduction of oxalate by A. niger. Furthermore, when the fungus was incubated in aluminium-free media supplemented with 0.1 mM of phosphate, oxalate production increased up to 281.5 μmol.g-1, while at 1.85 mM of available phosphate only 80.7 μmol.g-1 of oxalate was produced. This indicates that oxalic acid is produced by fungus not as a mean to detoxify aluminium, but as an attempt to gain access to additional phosphate.
Efficient hydrolysis of holocellulose depends on a proper balance between cellulase (endoglucanase, exoglucanase, β-glucosidase) and xylanase activities. The present study aimed to induce the production of cellulases and xylanases using liquid cultures (one, two, three, and four fungal strains on the same bioreactor) of wild strains of Trichoderma harzianum, Aspergillus niger, and Fusarium oxysporum. The strains were identified by amplification and analysis of the ITS rDNA region and the obtained sequences were deposited in Genbank. Enzymes (endoglucanase, exoglucansae, β-glucosidase, and xylanase activities) and the profile of extracellular protein isoforms (SDS-PAGE) produced by different fungal combinations (N = 14) were analyzed by Pearson's correlation matrix and principal component analysis (PCA). According to our results, induction of endoglucanase (19.02%) and β-glucosidase (6.35%) were obtained after 4 days when A. niger and F. oxysporum were cocultured. The combination of A. niger-T. harzianum produced higher endoglucanase in a shorter time than monocultures. On the contrary, when more than two strains were cultured in the same reactor, the relationships of competition were established, trending to diminish the amount of enzymes and the extracellular protein isoforms produced. The xylanase production was sensible to stress produced by mixed cultures, decreasing their activity. This is important when the aim is to produce cellulase-free xylanase. In addition, exoglucanase activity did not change in the combinations tested.
- MeSH
- Ascomycota enzymologie růst a vývoj izolace a purifikace metabolismus MeSH
- Aspergillus niger enzymologie růst a vývoj izolace a purifikace metabolismus MeSH
- biomasa MeSH
- bioreaktory mikrobiologie MeSH
- celulasy biosyntéza metabolismus MeSH
- celulosa metabolismus MeSH
- fermentace MeSH
- fungální proteiny biosyntéza metabolismus MeSH
- Fusarium enzymologie růst a vývoj izolace a purifikace metabolismus MeSH
- kokultivační techniky * MeSH
- mikrobiální interakce fyziologie MeSH
- průmyslová mikrobiologie metody MeSH
- Trichoderma enzymologie růst a vývoj izolace a purifikace metabolismus MeSH
- xylosidasy biosyntéza metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- aminy farmakokinetika metabolismus MeSH
- antioxidancia farmakokinetika metabolismus MeSH
- Aspergillus niger metabolismus patogenita účinky léků MeSH
- mitochondrie patologie účinky léků ultrastruktura MeSH
- mycelium metabolismus účinky léků ultrastruktura MeSH
- oxidační stres genetika MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- Aspergillus niger enzymologie metabolismus MeSH
- citráty biosyntéza MeSH
- fermentace MeSH
- techniky in vitro MeSH
- Publikační typ
- srovnávací studie MeSH
