బయోప్రాసెసింగ్ & బయోటెక్నిక్స్ జర్నల్

 Carotene desaturation, an essential step in the carotenoid biosynthesis pathway, is catalyzed by two enzymes, phytoene desaturase (PDS) and ζ-carotene desaturase (zeta carotene desaturase, ZDS). Here we describe cloning and E. coli expression of zdsfc, a novel Ficus carica ζ-carotene desaturase catalyzing dehydrogenation of ζ-carotene into neurosporene and finally lycopene. The ζ-carotene desaturase (ZDS) gene was amplified from the fig tree  by rapid amplification of cDNA ends (RACE) and spanned a 1746 bp open reading frame (ORF), encoding a protein of 582 amino acid residues with a predicted molecular weight of 64kD. The N-terminal region of this polypeptide contained a putative transit sequence for plastid targeting. By phylogenetic and sequence analyses, zdsfc showed high homology with previously described ζ-carotene desaturases from higher plant species [1-4]. Additionally, sequence analysis revealed a high degree of conservation among plant ZDSs. The deduced ZDS protein, designated zdsfc, also contains an N-terminus dinucleotide-binding, followed by a conserved region identified in other carotene desaturase sequences. These data, taken together, confirm our cloned zdsfc as an integral part of the ZDS family of proteins.

 This paper is concerned with optimization of submerged culture conditions for mycelial growth and Exopolysaccharides (EPS) yield with Coriolus versiolor by both one-factor-at-a-time and orthogonal matrix methods. Glucose and yeast-Extracts were identified to be the most suitable carbon and nitrogen sources, respectively. The optimal initial pH, inoculum size and liquid volume for mycelial growth and EPS yield were 5.0, 8% and 150mL/500mL, respectively. Subsequently, the concentration of glucose, yeast-extract, KH₂PO₄, and MgSO₄•7H₂O were optimized using the orthogonal matrix method. The effects of media composition on the mycelial growth of Coriolus versiolor were in the order of glucose >KH₂PO₄ > yeast-extract > MgSO₄•7H₂O, and those on EPS yield were in the order of glucose >MgSO₄•7H₂O> yeast-extract >KH₂PO₄.The optimal concentrations for enhanced yield were determined as 30 g/L glucose, 7.0 g/L yeast-extract, 1.0 g/L KH₂PO₄, 1.0 g/L MgSO₄•7H₂O, and 40 g/L glucose, 6.0 g/L yeast-extract, 1.0 g/L KH₂PO₄, 1.5 g/L MgSO₄•7H₂O for mycelial and EPS yield, respectively. The verification experiments confirmed the final medium. This optimization strategy (30 g/L glucose, 7.0 g/L yeast-extract, 2.0 g/L KH₂PO₄ and 0.5 g/L MgSO₄•7H₂O) in shake flask culture lead to a mycelial yield of 5.18 g/L, and EPS yield of 0.64 g/L, respectively, which were considerably higher than those obtained in preliminary studies. Under optimal culture conditions, the maximum EPS concentration in a 5-L stirred-tank bioreactor was 0.75 g/L, while the maximum mycelial yield was 8.55 g/L. This also corresponded to 14.67% and 39.42% enhancement in EPS yield and mycelial dry weight, respectively, compared with the verification test results.

 Dimeric keratinase from Bacillus licheniformis ER-15 completely degraded 25g boiled native chicken feather to feather meal within 8h at pH 8, 50°C and 150rpm. Feather degradation was a linear function of enzyme concentration and 2.5g chicken feather was degraded in presence of 1200U keratinase. Process for feather meal production comprised soaking of 25g feather in 250ml water followed by boiling for 10min-20min before enzyme addition. Feather meal thus produced was dried at 80°C and ground to obtain feather meal powder. Feather meal contained 14% nitrogen, 44% carbon with all essential amino acids and showed 73% in-vitro digestibility.

Heavy metal contents in traditional Asian herbs need to be monitored closely because of potential health risks of heavy metals at high concentrations. Total amount of toxic heavy metals (lead, copper, cadmium, chromium, mercury and arsenic) in each herb listed in the recipe of Ssanghwatang (one of the most popular herbal drinks in Korea) was 22.6-42.1 mg/kg as determined by Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES). These levels were notable because they were comparable to or above the guideline (30 mg/kg) set by Korean Food and Drug Administration (KFDA). However, herbal tea prepared by decoction preparation (a process of extracting medicinal components from the herbs by boiling them in water) contained only 6.35-12.2 % of the original toxic heavy metals in the herbs. Instead the remainder of toxic heavy metals was found in the herbal residue and the hempen cloth filter. The result suggests that drinking herbal tea is a much safer way of taking beneficial nutrients from the herbs as compared with consuming the whole herbs. 

 Leaching, or solid-liquid extraction, is the first step that must be done in the recovery process of a metabolite produced by Solid State Fermentation (SSF). In this work, the leaching of a Polygalacturonase (PG) produced by a strain of Aspergillus niger by SSF of citrus dried pulp was performed. A fractionated factor design 24-1 was developed to establish the influences of five factors: solid-liquid ratio, temperature, pH, agitation and surfactant addition (Tween 80). Agitation and surfactant addition effects were confounded by second order effects according to the fractionated factor design. Results showed that pH and surfactant addition did not influence the recovery process. The leaching process was characterized through the corresponding kinetic parameters for PG and total protein recovery, corresponding to first order kinetics. In the case of PG leaching, the theoretical CS was 17993 U L-1 and the k was 0.107 min-1, and in the case of total protein extraction, values were 13159 mg L-1 and 0.177 min-1, respectively. The process was improved by using a system of six successive steps. The results showed that when a single step was performed the concentration obtained was 137 U g-1 (d.b.), while after successive extractions the PG extracted achieved a concentration of 537 Ug^-1 (d.b.), improving the process by 74%.