György Szakács

Production of lovastatin by a wild strain of Aspergillus terreus

Of 68 Aspergillus terreus, three produced lovastatin with equivalent or better yield than strain ATCC 20542 originally described for lovastatin production. Medium optimization experiments with the best isolate (TUB F-514) indicated that lactose, rapeseed meal and KNO3 were the best carbon, organic nitrogen and inorganic nitrogen sources, respectively. In shake-flasks with optimized medium containing 4 % (w/v) lactose, 400 μg lovastatin/ml was produced, with a yield of 10 mg/g lactose. In solid substrate fermentation on extracted sweet sorghum pulp supplemented with cheese whey 1500 μg lovastatin/g dry weight was produced with a yield of 37.5 mg/g lactose.

Biotreatment of desized cotton fabric by commercial cellulase and xylanase enzymes

Abstract Desized cotton fabric was subjected to biotreatment with seven commercial cellulase and hemicellulase enzymes in non-agitated and agitated systems at 50°C for 0.5–4 h. The enzymes performed better in agitated bath than in non-agitated ones. All enzymes at 1 g/l concentration in 2 h caused weight loss less than 6%. Those three enzymes (Celluclast 1.5, Cellusoft L and Cellulase (EBT)) which exhibited the highest filter paper activity (FPA) showed the most aggressive action on cotton in agitated system at 1 g/l concentration when time of treatment exceeded 2 h.

Kinetic resolution of 1-(benzofuran-2-yl)ethanols by lipase-catalyzed enantiomer selective reactions

Abstract Kinetic resolution of racemic 1-(benzofuran-2-yl)ethanols rac - 1a – d was performed by lipase-catalyzed enantiomer selective acylation ( E ≫100) yielding (1 R )-1-acetoxy-1-(benzofuran-2-yl)ethanes ( R )- 2a – d and (1 S )-1-(benzofuran-2-yl)ethanols ( S )- 1a – d in highly enantiopure form. The degree of enantiomer selectivity for enzymatic alcoholysis/hydrolysis processes starting from racemic 1-acetoxy-1-(benzofuran-2-yl)ethane rac - 2 was also tested under various conditions including supercritical CO 2 medium. Racemization-free lipase-catalyzed ethanolysis of the (1 R )-1-acetoxy-1-(benzofuran-2-yl)ethanes ( R )- 2a – d yielded almost quantitatively the enantiopure (1 R )-1-(benzofuran-2-yl)ethanols ( R )- 1a – d .

l-leucine aminopeptidase production by filamentous Aspergillus fungi.

Aims:  To screen various filamentous fungi belonging to Aspergillus spp. producing leucine and methionine aminopeptidases.

Degradation of lignin-containing materials by xylanase in biopreparation of cotton

Solubilization of lignin and carbohydrates from the lignin-holocellulose structure of cotton seed-coat fragments was investigated by UV/VIS spectrometry. Xylanase (Pulpzyme HC) pre-treatment partially destroyed the lignocellulosic structure of the seed-coat fragments, producing reducing sugars and soluble lignin in the supernatant. Furthermore, the pre-treatment by enzyme enhanced the delignification in the subsequent alkaline scouring process and increased the lightness of the substrate.

Production of α-amylase with Aspergillus oryzae on spent brewing grain by solid substrate fermentation

Ten Aspergillus oryzae strains were screened in solid substrate fermentation for α-amylase production on spent brewing grain (SBG) and on corn fiber. SBG proved to be a better substrate for enzyme production than corn fiber. A Plackett-Burman experimental design was used to optimize the medium composition for the best strain. Solid substrate fermentation on optimized medium with A. oryzae NRRL 1808 (=ATCC 12892) strain in stationary 500-mL Erlenmeyer flask culture yielded 4519 U of α-amylase/g of dry matter substrate in 3 d. The whole solid substrate fermentation material (crude enzyme, in situ enzyme) may be considered a cheap biocatalytic material for animal feed rations and for bioalcohol production from starchy materials.

Production of chitinolytic enzymes with Trichoderma longibrachiatum IMI 92027 in solid substrate fermentation.

Thirty Trichoderma strains representing 15 species within the genus were screened for extracellular production of chitinolytic enzymes in solid substrate fermentation. Trichoderma longibrachiatum IMI 92027 (ATCC 36838) gave the highest yield (5.0 IU/g of dry matter of substrate) after 3 d of fermentation on wheat bran-crude chitin (9:1 mixture) medium. The optimal moisture content (66.7%), chitin content (20%), initial pH of the medium (2.0–5.0), and time course (5 d) of solid substrate fermentation were determined for strain IMI 92027. Cellulase, xylanase, α-amylase, and β-xylosidase activities were also detected. The pH and temperature optima of the chitinase complex of T. longibrachiatum IMI 92027 were 4.5 and 55°C, respectively. The enzyme totally lost its activity at 70°C in 5 min in the absence of the substrate but retained about 15% of its initial activity even at 70°C after a 60-min incubation in the presence of solid substrate fermentation solids. Purification of protein extract from the solid substrate fermentation material revealed high chitinolytic activities between pI 5.9 and 4.8, where N-acetyl-β-d-hexosaminidase and chitinase peaks have been found in the same pI range. Two chitinases of 43.5 and 30 kDa were purified at acidic pI.

Kinetic resolution of trans-2-acetoxycycloalkan-1-ols by lipase-catalysed enantiomerically selective acylation

Abstract Kinetic resolution of a series of racemic trans -cycloalkane-1,2-diol monoacetates rac - 2a – d was performed by enantiomerically selective transesterification with vinyl acetate catalysed by commercial and our own-prepared fungal lipases to yield diacetates ( R , R )- 3a – d and monoacetates ( S , S )- 2a – d in high enantiomeric purity. The monoacetates ( R , R )- 2a – d were also prepared from the racemic diacetates rac - 3a – d by lipase-catalysed hydrolysis.

Influence of EDTA complexing agent on biopreparation of linen fabric

In this work the ‘EDTA–enzyme–substrate’ interaction was investigated in linen biopreparation. The effect of EDTA on the degradation of non-cellulosic constituents during bioscouring with pectinase enzyme was investigated in detail. Greige linen fabric was treated with pectinase, pectinase supplemented with ethylenediamine-tetra-acetic acid (EDTA), and EDTA pre-treatment followed by pectinase, in a tumble agitated bath. Adding EDTA to the enzyme solution accelerated the degree of hydrolysis and resulted in higher reducing sugar liberation and more efficient calcium ion extraction, indicating a synergistic effect of enzyme and EDTA. However, when EDTA was applied as a pre-treatment, a decrease in the efficiency of the subsequent enzymatic hydrolysis was observed.

Bioprocessing of sweet sorghum with in situ-produced enzymes

Enzyme-assisted ensiling (ENLAC), usingin situ-produced enzymes fromGliocladium sp. TUB-F-498, preserved 80% of the sugar content of sweet sorghum, and facilitated its extraction by countercurrent diffusion. Thein situ enzyme was produced on the extracted sweet sorghum pulp by an 8-d solid substrate fermentation (SSF) with a yield of 4.6 cellulase and 400 IU/g dry wt xylanase. Two percent of the fermented substrate had cellulase and xylanase levels equivalent or superior to levels found in the commercial enzymes Celluclast and Viscozyme Novo at the 0.025% application level in ENLAC.Thein situ-production of enzymes on recyclable substrates may reduce bioprocessing costs significantly. In this ENLAC process, the cost of thein situ enzymes is estimated to be about