2 research outputs found
Brewers' spent grain as substrates for production of cellulolytic and hemicellulolytic enzymes by different Aspergillus species
Brewers' spent grain (BSG) is the major by-product of the brewing industry, representing around 85% of the
total by-products generated. It is a lignocellulosic material containing about 38% cellulose, 29%
hemicellulose, chiefly arabinoxylans, and 13% lignin. The production of cellulolytic and hemicellulolytic
enzymes using this material as substrate represent an eco-friendly strategy for the lignocellulosic biomass
hydrolysis, generating fermentable sugars that can be converted into high- added value products, such as
bioethanol, lactic acid, xylitol and others. Thus, this work aimed to evaluate the potential of cellulolytic and
hemicellulolytic enzymes production by some Aspergillus species cultivated in BSG. Fungi were grown in
minimum media, pH 6.5, with 1% BSG and inoculum was done with 107spores/mL, cultivated at 30°C, 120
rpm, for 5 days. Every 24 hours 2 mL of the samples were collected. The enzymatic activity was performed
after the incubation of the crude extract with 1% Linear arabinan, Xylan from beechwood, Xyloglucan, Locust
bean gum and CMC, at 50°C for 60 minutes and the reducing sugars were determined using dinitrosalicylic
acid (DNS). Synthetic substrates (2 mM of PNP--L-arabinofuranoside, PNP--D-xylopyranoside, PNP--Dglucopyranoside
and PNP--D-cellobioside) were also used at the same conditions. The extract from A.
niveus showed the best arabinanase (0.284 U/mL) and -glucosidase (0.126 U/mL) activities after 48 and 96
hours of cultivation, respectively. On the other hand, the extract from A. brasiliensis presented the best
activities of -L-arabinofuranosidase (0.129 U/mL), -xylosidase (0.265 U/mL) and xylanase (2.15 U/mL)
when cultivated for 48 hours. After 72 hours, this fungus also showed the best activities for xyloglucanase
(1.06 U/mL), mannanase (0.617 U/mL) and endoglucanase (0.254 U/mL). The extract produced by A. flavus
presented the best cellobiohydrolase activity with 0.113 U/mL after 120 hours of cultivation. It is important to
mention that A. awamori, A. clavatus and A. terreus also showed good levels of different enzymes produced
but they were not the best producers. These data suggest the great potential of different cellulolytic and
hemicellulolytic enzymes production using BSG as substrate, which represents an eco-friendly destination
for the residues and can generate high-added value products with great biotechnological application.Coordenação de Aperfeiçoamento de Pessoal de NÃvel Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Institutos Nacionais de Ciência e Tecnologia (INCT)Fundação para a Ciência e a Tecnologia (FCT)info:eu-repo/semantics/publishedVersio
Production of an enzymatic cocktail by Aspergillus awamori grown on corn straw with stirred tank bioreactor
Increased agroindustrial activity has led to the accumulation of large amounts of lignocellulosic material
(LCM). LCM is nature's most abundant source of renewable carbon, representing a valuable industrial
substrate with potential for many applications. Thus, the objective of this work was to screen for different
holocellulases and to analyze the production of an Aspergillus awamori enzyme cocktail grown in corn straw
(CS) using a stirred tank bioreactor. Screening was performed with A. clavatus, A. flavus, A. terreus, A.
niveus, A. awamori and A. brasiliensis cultivated in minimal medium (MM), with 1% CS at 30 ºC or 37 ºC (for
A. niveus), 120 rpm, for 5 days. Xylanase (XYN) and endoglucanase (EG) activities were evaluated by
formation of reducing sugars using dinitrosalicylic acid (DNS). Cellobiohydrolase (CBH), -glucosidase (BGL)
and -xylosidase (BXL) were determined by cleavage of PNP--D-cellobioside, PNP--D-glucopyranoside
and PNP--D- xylopyranoside, respectively. After screening, a pre-inoculum was prepared with the best
enzyme producer using a 500 mL MM flask and incubated at 30 °C, 120 rpm for 48 hours. The increase of
enzyme production was performed in a Benchtop BioFlo 310 bioreactor, with 4.5 L of MM and 1% of CS, and
was then inoculated the best enzyme producer. Cultivation was performed at 30 °C, pH 6.5, 275 rpm, air flow
2 v.v.m., for 5 days. During the screening, all fungi presented EG, CBH, BGL, XYN and BXL activities.
However, A. awamori was chosen to continue the experiments because of its BXL activity which was 12.6
times higher than that produced by A. niveus. At the scale-up stage, XYN production (47.80 U/ mL) increased
4.1-fold compared to flask activity (11.52 U/mL). BXL also showed 1.6-times higher activity, as well as EG,
CBH and BGL, which improved 2.3, 3.3 and 1.2 times their activities, respectively. It was concluded that the
staggering of cocktail production improved the enzymatic activities and that corn straw is an excellent source
of induction. Furthermore, this cocktail has the potential to be applied in the hydrolysis of different LCM due
to the range of holocellulases present.Coordenação de Aperfeiçoamento de Pessoal de NÃvel Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Institutos Nacionais de Ciência e Tecnologia (INCT)Fundação para a Ciência e a Tecnologia (FCT)info:eu-repo/semantics/publishedVersio