This review aims to present current knowledge of the fungi involved in lignocellulose degradation with an overview of the various classes of lignocellulose‐acting enzymes engaged in the pretreatment ...and saccharification step. Fungi have numerous applications and biotechnological potential for various industries including chemicals, fuel, pulp, and paper. The capability of fungi to degrade lignocellulose containing raw materials is due to their highly effective enzymatic system. Along with the hydrolytic enzymes consisting of cellulases and hemicellulases, responsible for polysaccharide degradation, they have a unique nonenzymatic oxidative system which together with ligninolytic enzymes is responsible for lignin modification and degradation. An overview of the enzymes classification is given by the Carbohydrate‐Active enZymes (CAZy) database as the major database for the identification of the lignocellulolytic enzymes by their amino acid sequence similarity. Finally, the recently discovered novel class of recalcitrant polysaccharide degraders‐lytic polysaccharide monooxygenases (LPMOs) are presented, because of these enzymes importance in the cellulose degradation process.
Marine microalgae and cyanobacteria are sources of diverse bioactive compounds with potential biotechnological applications in food, feed, nutraceutical, pharmaceutical, cosmetic and biofuel ...industries. In this study, five microalgae,
sp. S5,
D1,
sp. D3,
sp. Z3 and
sp. C6, and the cyanobacterium
sp. C1 were isolated from the Adriatic Sea and characterized regarding their growth kinetics, biomass composition and specific products content (fatty acids, pigments, antioxidants, neutral and polar lipids). The strain
sp. D3, showing the highest specific growth rate (0.009 h
), had biomass productivity of 33.98 ± 0.02 mg L
day
. Proteins were the most abundant macromolecule in the biomass (32.83-57.94%, g g
).
D1 contained significant amounts of neutral lipids (68.36%), while the biomass of
sp. D3,
sp. Z3,
sp. C6 and
sp. C1 was rich in glycolipids and phospholipids (75%). The lipids of all studied microalgae predominantly contained unsaturated fatty acids. Carotenoids were the most abundant pigments with the highest content of lutein and neoxanthin in representatives of Chlorophyta and fucoxanthin in strains belonging to the Bacillariophyta. All microalgal extracts showed antioxidant activity and antimicrobial activity against Gram-negative
and
and Gram-positive
.
The underutilized biomass and different organic waste streams are nowadays in the focus of research for renewable energy production due to the effusive use of fossil fuels and greenhouse gas ...emission. In addition, one of the major environmental problems is also a constant increase of the number of organic waste streams. In a lot of countries, sustainable waste management, including waste prevention and reduction, has become a priority as a means to reduce pollution and greenhouse gas emission. Application of biogas technology is one of the promising methods to provide solutions for both actual energy-related and environmental problems. This review aims to present conventional and novel biogas production systems, as well as purification and upgrading technologies, nowadays applicable on a large scale, with a special focus on the CO
and H
S removal. It also gives an overview of feedstock and the parameters important for biogas production, together with digestate utilization and application of molecular biology in order to improve the biogas production.
The growing commercial application of microalgae in different industry sectors, including the production of bioenergy, pharmaceuticals, nutraceuticals, chemicals, feed, and food, demands large ...quantities of microalgal biomass with specific compositions produced at reasonable prices. Extensive studies have been carried out on the design of new and improvement of current cultivation systems and the optimisation of growth medium composition for high productivity of microalgal biomass. In this study, the concentrations of the main macronutrients, silicon, nitrogen and phosphorus, essential for the growth of diatom
sp. S5 were optimised to obtain a high biomass concentration. The effect of main macronutrients on growth kinetics and cell composition was also studied. Silicon had the most significant effect on diatom growth during batch cultivation. The concentration of biomass increased 5.45-fold (0.49 g L
) at 1 mM silicon concentration in modified growth medium compared to the original Guillard f/2 medium. Optimisation of silicon, nitrogen, and phosphorus quantities and ratios further increased biomass concentration. The molar ratio of Si:N:P = 7:23:1 mol:mol:mol yielded the highest biomass concentration of 0.73 g L
. Finally, the fed-batch diatom cultivation of diatom using an optimised Guillard f/2 growth medium with four additions of concentrated macronutrient solution resulted in 1.63 g L
of microalgal biomass. The proteins were the most abundant macromolecules in microalgal biomass, with a lower content of carbohydrates and lipids under all studied conditions.
An innovative integrated bioprocess system for bioethanol production from raw sugar beet cossettes (SBC) and arabitol from remaining exhausted sugar beet cossettes (ESBC) was studied. This integrated ...three-stage bioprocess system is an example of the biorefinery concept to maximise the use of raw SBC for the production of high value-added products such as sugar alcohols and bioethanol.
The first stage of the integrated bioprocess system was simultaneous sugar extraction from SBC and its alcoholic fermentation to produce bioethanol in an integrated bioreactor system (vertical column bioreactor and stirred tank bioreactor) containing a high-density suspension of yeast
(30 g/L). The second stage was the pretreatment of ESBC with dilute sulfuric acid to release fermentable sugars. The resulting liquid hydrolysate of ESBC was used in the third stage as a nutrient medium for arabitol production by non-
yeasts (
CBS 10155 and
CBS 11463).
The obtained results show that the efficiency of bioethanol production increased with increasing temperature and prolonged residence time in the integrated bioreactor system. The maximum bioethanol production efficiency (87.22 %) was observed at a time of 60 min and a temperature of 36 °C. Further increase in residence time (above 60 min) did not result in the significant increase of bioethanol production efficiency. Weak acid hydrolysis was used for ESBC pretreatment and the highest sugar yield was reached at 200 °C and residence time of 1 min. The inhibitors of the weak acid pretreatment were produced below bioprocess inhibition threshold. The use of the obtained liqiud phase of ESBC hydrolysate for the production of arabitol in the stirred tank bioreactor under constant aeration clearly showed that
CBS 10155 with 8.48 g/L of arabitol (
=0.603 g/g and bioprocess productivity of 0.176 g/(L
h)) is a better arabitol producer than
CBS 10155.
An innovative integrated bioprocess system for the production of bioethanol and arabitol was developed based on the biorefinery concept. This three-stage bioprocess system shows great potential for maximum use of SBC as a feedstock for bioethanol and arabitol production and it could be an example of a sustainable 'zero waste' production system.
Heterotrophic cultivation of
Euglena gracilis
was carried out on synthetic (Hutner medium) and complex cultivation media in order to optimize production of β-1,3-glucan (paramylon). For preparation ...of complex media, various industrial by-products (e.g., molasses, corn steep solid, yeast extract, and beef extract) were used with or without addition of pure compounds glucose, galactose, fructose, lactose, maltose, sucrose, and (NH
4
)
2
HPO
4
. Heterotrophic cultivation of
E. gracilis
was performed in Erlenmeyer flasks and additionally confirmed during research in the stirred tank bioreactor. The results clearly show that
E. gracilis
can easily metabolize glucose and fructose as carbon sources and corn steep solid as complex nitrogen and growth factors source for biomass growth and paramylon synthesis. Furthermore, it was also proved that addition of (NH
4
)
2
HPO
4
, beef extract, or gibberellic acid did not have positive effect on the biomass growth and paramylon synthesis. After optimization of complex medium composition and verification in the stirred tank bioreactor, it was concluded that medium composed of glucose (20 g/L) and corn steep solid (30 g/L) is the most suitable complex medium for industrial cultivation of
E. gracilis
and paramylon production.
Microbial lipids produced from lignocellulosic biomass are sustainable alternative feedstock for biodiesel production. In this study, corn cobs were used as a carbon source for lipid production and ...growth of oleaginous yeast Trichosporon oleaginosus. Lignocellulosic biomass was subjected to alkali and acid pretreatment using sulfuric acid and sodium hydroxide under different temperatures, catalyst concentrations and treatment times. Pretreatment of corn cobs was followed by cellulase hydrolysis. Hydrolysis of alkali pretreated (2% NaOH at 50 °C for 6 h, 1% NaOH at 50 °C for 16 h, 2% NaOH at 121 °C for 1 h, 1% NaOH at 121 °C for 2 h) and acid pretreated (1% H2SO4 120 °C for 20 min, and 2% H2SO4 120 °C for 10 min) corn cobs resulted in more than 80% of the theoretical yield of glucose. The effect of substrate (5, 10, 15 and 20%, g g−1) and cellulase loading (15 and 30 Filter Paper Units per gram of glucan, FPU g−1) on fermentable sugar yield was also studied. The maximal glucose concentration of 81.64 g L−1 was obtained from alkali-pretreated corn cobs (2% NaOH at 50 °C for 6 h) at 20% substrate loading and 30 FPU of Cellic CTec2 g−1 of glucan. Enzymatic hydrolysates of pretreated biomasses and filtrates of lignocellulosic slurries obtained after pretreatment were used for growth and lipid synthesis by T. oleaginosus. The highest lipid concentration of 18.97 g L−1 was obtained on hydrolysate of alkali-pretreated corn cobs (with 1% NaOH at 50 °C for 16 h) using a 15% (g g−1) substrate loading and 15 FPU g−1 of cellulase loading. Significant lipid accumulation was also achieved using undetoxified filtrates of pretreated slurries as substrates. Results showed that pretreated corn cobs and undetoxified filtrates are suitable carbon sources for the growth and efficient accumulation of lipids in T. oleaginosus.
Biodiesel is still mainly produced from different vegetable (e.g., rapeseed, palm, soybean, sunflower, and used cooking oils) oils and animal fats, and therefore it has a negative impact on food and ...feed prices. For biodiesel production as an alternative feedstock, lipids from oleaginous microorganisms could be used. One of the oleaginous microorganisms is yeast Trichosporon oleaginosus that has the capacity to grow and accumulate lipids on different lignocellulosic hydrolysates. In this study, corn cobs were pretreated by alkali at loading from 0.08 to 1.6 g/g dry weight of untreated (raw) corn cobs (g NaOH/gDW_UCC) at 121 °C for 30 min. In a further step, alkaline pretreated corn cobs were subjected to the enzymatic hydrolysis by using commercial multienzymes mixtures. The optimal alkali loading (0.16 g/gDW_UCC) was related to the highest glucose and xylose yields which were observed during enzymatic hydrolysis of substrate. In this study, T. oleaginosus was applied for lipid production on the enzymatic corn cobs hydrolysates by following bioprocess configurations: separate hydrolysis and lipid production (SHLP) and simultaneous saccharification and lipid production (SSLP). The SSLP was characterized by higher lipid yield (88.88 mg/gDW_UCC) and productivity (2.4 g/(L day)) as well as significant bioprocess time reduction. On the basis of the above-mentioned facts, it is obvious that SSLP with T. oleaginosus has great potential for application in industrial scale.
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•Wheat beer can contain high levels of emerging mycotoxins.•Use of fungicides in the field reduced mycotoxin content in malting and brewing products.•Emerging mycotoxins should be ...included into legislation.
The aim was to determine the mycotoxin transfer rate into beer during a semi-industrial production process and the effect of fungicide treatment in the field on mycotoxins concentrations in beer. To ensure the usual practical agronomical conditions, sample A was treated with fungicide Prosaro® 250, and sample B was infected with Fusarium culmorum spores, in order to obtain infected malt. Malt was produced using standard procedure and beer was produced in a semi-industrial unit. During fermentation measurement of sugars (maltotriose and maltose), glycerol and ethanol content was performed on a daily basis. Multiple toxins were determined in malt and beer. Deoxynivalenol (DON), its modified plant metabolite DON-3-glucoside (DON-glucoside), brevianamide F, tryptophol, linamarin, lotaustralin, culmorin (CUL), 15-hydroxy-CUL and 5-hydroyx-CUL were detected in all samples. Results indicate that F. culmorum infection did not influence the fermentation process or the alcohol concentration.
Microalgal biomass is an excellent platform for producing food, feed, nutraceuticals, pharmaceuticals, and biofuels. This study aimed to investigate the effect of the trophic mode of cultivation ...(phototrophic, heterotrophic, and mixotrophic) on the growth and biomass composition of Chlorella vulgaris S2. The contents of lipids and carbohydrates, as well as the fatty acid composition of total lipids, were studied. The effects of the carbon-to-nitrogen ratio (C:N) and the organic carbon concentration of the growth media under mixotrophic and heterotrophic conditions were also investigated. The C:N ratio of 30 mol mol−1 favoured lipid synthesis, and the C:N ratio of 10 mol mol−1 favoured carbohydrate synthesis. Maximal lipid and biomass productivities (2.238 and 0.458 g L−1 d−1, respectively) were obtained under mixotrophic conditions at the C:N ratio of 50 mol mol−1 and glucose concentration of 50 g L−1. Fed-batch cultivation conducted in a stirrer tank bioreactor under heterotrophic growth conditions increased biomass (2.385 g L−1 d−1, respectively) and lipid (0.339 L−1 d−1) productivities ~50 and ~60 times compared to the fed-batch phototrophic cultivation, respectively. The trophic mode, growth phase, and growth medium composition significantly influenced the fatty acid composition. Under mixotrophic and heterotrophic growth conditions, lipid accumulation is associated with an increase in oleic acid (C18:1) content. Mixotrophically grown biomass of Chlorella vulgaris S2 under optimised conditions is a suitable source of lipids for biodiesel production.
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