Produção de celulases e xilanases por uma nova espécie fúngica - Achaetomium lippiae URM 7547 - utilizando a fibra de coco verde pré-tratada por explosão a vapor
Endophytic microorganisms, which can be bacteria, fungi or protozoa, are poorly studied. It is estimated that there are more than 250,000 different species of plants and one million endophytes in the world, which characterizes an average of four associated species for each plant species. Because...
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| Μορφή: | Dissertação |
| Γλώσσα: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Θέματα: | |
| Διαθέσιμο Online: | https://repositorio.ufrn.br/handle/123456789/48367 |
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| Περίληψη: | Endophytic microorganisms, which can be bacteria, fungi or protozoa, are
poorly studied. It is estimated that there are more than 250,000 different species of plants
and one million endophytes in the world, which characterizes an average of four
associated species for each plant species. Because they are inside the plant, these
microorganisms can be a rich source of biomolecules of industrial interest, such as the
production of hemicellulolytic enzymes. In this context, this study was the first to study
the endophytic fungal species Achaetomium lippiae URM 7547, with the objective of
evaluating the production of cellulases and xylanases in submerged fermentation (FSm)
using the fiber of pre-treated blast-treated green coconut husk as a substrate. Initially, the
potential of A. lippiae URM 7547 to produce hydrolases (amylase, lipase, protease,
cellulase, xylanase and pectinase) in solid culture media (72 h at 30 °C) with specific
inducing substrates was evaluated. As a control, for comparison of results, growth of the
fungus Thricoderma reesei CCT 2768 was used under the same induction conditions. A.
lippiae URM 7547 presented itself as a potential producer of amylases, proteases and
cellulases, with an enzyme index (IE) greater than 1.5, as well as T. reesei CCT 2768.
The yield of substrate conversion into cell biomass (Yx/s) of A. lippiae URM 7547 and its
maximum growth rate (µmax) in liquid medium containing glucose or xylose in three
concentrations and nutrient medium with mineral sources were also quantified. and
nitrogen in order to verify if the fungus is adept to submerged crops and what is the best
condition for its growth. The best results for the liquid medium containing glucose were
at 96 h of culture in the medium containing peptone and yeast extract, with Yx/s equal to
0.062 ± 0.04 g.g-1, 0.072 ± 0.04 g.g-1, and 0.076 ± 0.03 g.g-1, for the initial concentrations
of 5, 10 and 20 g.L-1 of sugar, respectively. For the medium containing xylose, the best
result was during 144 h of cultivation, with Yx/s values equal to 0.52 ± 0.08 g.g-1, 0.59 ± 0.09 g.g-1
and 0.65 ± 0.03 g.g-1 to 5, 10 and 20 g.L-1, respectively, in the same medium
containing peptone and yeast extract. Finally, the pre-treatment of green coconut biomass
and FSm were carried out for the production of cellulases and xylanases. The
lignocellulosic characterization of green coconut fiber in natura and after pre-treatment
by steam explosion indicated that there was a 14% decrease in extractables in the pretreated fiber in relation to in natura fiber, since these materials are easily removed by
solvents. There was also an 8% increase in cellulose content and a 6% decrease in
hemicellulose, while lignin remained statistically the same (p>0.05). In FSm, the
conditions of 33 °C, initial concentration of 109 spores.mL-1, and 30.0 g.L-1 of pre-treated
biomass were the ones that led to a better yield in relation to the four quantified enzymes,
with enzymatic activities (U.mL-1) of 0.41 ± 0.06, 5.94 ± 0.31, 0.08 ± 0.03 and 9.12 ±
0.28 for FPase, CMCase, cellobiase and xylanase, respectively. Finally, A. lippiae URM
7547 proved to be a good producer of cellulases and xylanases, in addition to other
hydrolytic enzymes such as amylases and proteases, with an excellent growth
performance in submerged media. |
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