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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.112, #2)

A β-glucosidase from Sclerotinia sclerotiorum by Smaali M. Issam; Gargouri Mohamed; Legoy Marie Dominique; Maugard Thierry; Limam Farid; Marzouki Nejib (pp. 63-77).

The filamentous fungus Sclerotinia sclerotiorum, grown on a xylose medium, was found to excrete one β-glucosidase (β-glu x). The enzyme was purified to apparent homogeneity by ammonium sulfate precipitation, gel filtration, anion-exchange chromatography, and high-performance liquid chromatography (HPLC) gel filtration chromatography. Its molecular mass was estimated to be 130 kDa by HPLC gel filtration and 60 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, suggesting that β-glu x may be a homodimer. For p-nitrophenyl β-d-glucopyranoside hydrolysis, apparent K _m and V _max values were found to be 0.09 mM and 193 U/mg, respectively, while optimum temperature and pH were 55–60°C and pH 5.0, respectively. β-Glu x was strongly inhibited by Fe²⁺ and activated about 35% by Ca²⁺. β-Glu x possesses strong transglucosylation activity in comparison with commercially available β-glucosidases. The production rate of total glucooligosaccharides (GOSs) from 30% cellobiose at 50°C and pH 5.0 for 6 h with 0.6 U/mL of enzyme preparation was 80 g/L. It reached 105 g/L under the same conditions when using cellobiose at 350 g/L (1.023 M). Finally, GOS structure was determined by mass spectrometry and ¹³C nuclear magnetic resonance spectroscopy.

Keywords: β-Glucosidase; Sclerotinia sclerotiorum ; purification; oligosaccharide synthesis

Roles of pH in biologic production of hydrogen and volatile fatty acids from glucose by enriched anaerobic cultures by Xian-Jun Zheng; Han-Qing Yu (pp. 79-90).

Batch experiments were carried out to study the roles of pH in the biologic production of hydrogen and volatile fatty acids from glucose by enriched anaerobic cultures. The results showed that 95–99% of glucose in wastewater was acidified at 30°C and pH 4.0–8.5. Hydrogen yield fluctuated between 1.30 and 1.57 mol of H₂/mol of glucose when the reactor was operated at pH 4.0–5.0. However, a further increase in pH led to a considerable decrease in hydrogen yield, especially for the cases at pH 7.5 and 8.0. Acetate, propionate, butyrate, and ethanol were the key products of acidogenesis. Production of butyrate was favored at pH 4.0–5.0, whereas production of acetate was favored at pH 6.0–8.0. A modified Gompertz equation is able to properly describe the batch production of hydrogen from glucose. The optimum pH for the specific hydrogen production was found to be 5.5, close to 5.7, the optimum pH calculated using a semiempirical model.

Keywords: Anaerobic fermentation; glucose; hydrogen production; pH; volatile fatty acids

Addition of polyglycol to old culture of Phanerochaete chrysosporium by Irena Grgič; Anton Perdih (pp. 91-99).

Polyglycols increased lignin peroxidase activity in shaken cultures of Phanerochaete chrysosporium even when they were added to an old fungus (5 or 10 d after inoculation). The effects depended on the polyglycol mol wts (10²–10⁶ Daltons) as well as on the backbone structure (i.e., poly[ethylene glycol], poly[butylene glycol], poly[propylene glycol]) and terminal groups (i.e., poly[ethylene glycol], poly[ethylene glycol] methyl ether, poly[ethylene glycol] dimenthyl ether). The residual quantity of polyglycol in the biomass and in the culture filtrate also varied among different polyglycols. The polyglycols act after being adsorbed to the cell membrane exaggerating the asymmetry of the membrane environment. In old fungus, the incompatibility of polyglycols and glycans decreases the adsorption and the effect of high mol wtpolyglycols.

Keywords: Fungi; lignin peroxidase; Phanerochaete chrysosporium ; poly(glycol)

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (chlorophyta) by Shin Hirayama; Masashi Miyasaka; Hideomi Amano; Yoshito Kumagai; Nobuhiro Shimojo; Teruyoshi Yanagita; Yoshiro Okami (pp. 101-110).

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva lactuca was selected from the “Marine Park” in Tokyo Bay, and its growth rate (g-dry/[m²·d]) was measured using model reactors located on the land or on the surface of the sea at Yokohama. The growth rate of U. lactuca was recorded to be approx 20 g-dry/(m²·d), which is estimated to be 10 times greater than that in a natural field in the Marine Park. In addition, this growth rate was higher than that of conventional crops such as corn and rice on a farm or paddy. These data led us to newly design and propose a floating type of labor-efficient U. lactuca production system. d-Cysteinolic acid, which is included in U. lactuca as a major sulfur amino acid, inhibited the Fenton reaction, resulting in suppression of hydroxyl radical production and singlet oxygen. Addition of the sulfur amino acid (1µM) to HepG2 cells markedly decreased the intracellular triglyceride level. Hence, this proposed facility also has the potential for industrial production of a valuable resource for the primary prevention of lifestyle-related diseases using enriched or eutrophied seawater.

Keywords: d-Cysteinolic acid; reactive oxygen; triglyceride; Ulva lactuca ; seawater

Production of antitumoral retamycin during fed-batch fermentations of Streptomyces olindensis by Celso Ricardo Denser Pamboukian; Maria Câandida Reginato Facciotti (pp. 111-121).

Fed-batch runs were performed in order to correlate the production of retamycin, an anthracycline antibiotic produced by Streptomyces olindensis in submerged cultures, with the specific growth rate. Maximum retamycin production was achieved with an exponential feed rate, controlling the specific growth rate at a low value (0.03h⁻¹, about 10% of the maximum specific growth rate). Control of the specific growth rate at higher values (0.10 and 0.17 h⁻¹) caused a decrease in antibiotic production. Morphology, assessed by image analysis, was shown to be highly relevant in this process. Cell growth mainly in the form of clumps (90% clumps and 10% free filaments) led to better results than growth as clumps (75%) and free filaments (25%).

Keywords: Streptomyces ; fed batch; morphology; antibiotic; retamycin

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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.112, #2)

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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.112, #2)