Xylanase production by a novel halophilic bacterium increased 20-fold by response surface methodology

Industrial attributes of β-glucanase produced by Bacillus sp. CSB55 and its potential application as bio-industrial catalyst

The β-glucanase produced from Bacillus sp. CSB55 not only depicts the potent industrial characteristics but also relates as bio-industrial catalyst supporting the spontaneous formation of the products, high hydrolytic efficiency, and feasibility of the enzymatic reaction. A homogeneous β-glucanase (GluB55) was purified via various purification processes resulting in 11.69% yield and 14.24-fold purity. Biochemical characterization of the purified enzyme revealed the molecular mass of approximately 40 kDa, which was verified by zymography. The optimum activity of GluB55 was determined at pH 7.2 and 55 °C. GluB55 could highly hydrolyze carboxymethylcellulose and was stable over a wide range of pH, retaining more than 70% residual activity at pH 5.8-11.0 and carried 100% thermostability as high as 60 °C. In addition, it showed 68% residual activity at 70 °C. The N-terminal amino acid sequence of GluB55 was Ala-Asn-Pro-Glu-Leu-Val-Asn-X-Gln-Ala-X-X-Ala-X-Gln-Gly. The enzyme activity was stimulated by Co²⁺ (158.6%), Zn²⁺ (211.1%), Mn²⁺ (264.4%), and Ba²⁺ (211.4%). Enzyme kinetics showed K_m and V_max values of 0.022 mg mL^-1 and 994.56 ± 3.72 U mg^-1, respectively. Q₁₀ was calculated to be 1.12. ∆H, ∆G, and ∆S were low revealing that the formation of the transition phase and conversion to the product is very well organized. The lower the free energy change (∆G), the more feasible is the reaction.

Improved Production of Recombinant Human β-NGF in Escherichia coli - a Bioreactor Scale Study

Human nerve growth factor β (β-NGF) is considered a major therapeutic agent for treatment of neurodegenerative diseases. We have previously reported the optimized conditions for β-NGF overproduction in Escherichia coli in a shake-flask culture. In this study the optimal %DO (dissolved oxygen) and post induction temperature values for improved production of β-NGF were found in the bioreactor scale using response surface methodology (RSM) as the most common statistical method. Also, for further enhancement of the yield, different post-induction periods of time were selected for testing. In all experiments, the productivity level and bacterial cell growth were evaluated by western blotting technique and monitoring of absorbance at 600 nm, respectively. Our results indicated that %DO, the post-induction time and temperature have significant effects on the production of β-NGF. After 2 hours of induction, the low post induction temperature of 32°C and 20% DO were used to increase the production of β-NGF in a 5-l bioreactor. Another important result obtained in this study was that the improved β-NGF production was not achieved at highest dry cell weigh or highest cell growth. These results are definitely of importance for industrial β-NGF production.

Enhanced production of histamine dehydrogenase by Natrinema gari BCC 24369 in a non-sterile condition

The production of histamine dehydrogenase (HADH) by Natrinema gari BCC 24369, a halophilic archeaon isolated from fish sauce, was optimized and scaled up under a non-sterile condition. Through statistical design by Plackett-Burman design (PBD), casamino acid, NaCl, MgSO4·7H2O and FeCl2·4H2O were identified as the significant medium compositions influencing HADH production. Central composite design (CCD) was employed to identify the optimal values of individual composition yielding the maximum HADH production. The analysis indicated that the optimal medium was composed of 15 g/l casamino acid, 75 g/l MgSO4·7H2O, 273 g/l NaCl, 2.5 mg/l FeCl2·4H2O, 10 g/l yeast extract, 5 g/l sodium glutamate and 5 g/l KCl. Based on the one-factor-at-a-time (OFAT) method, the optimum initial pH of the culture medium and the incubation temperature for HADH production were 7.5 and 37 °C, respectively. The production of HADH under optimal conditions was 2.2-fold higher than that under un-optimized conditions. Owing to the halophilic nature of Nnm. gari BCC 24369, a more economical and eco-friendlier HADH production was developed under a completely non-sterile condition. In a 16-l batch cultivation of Nnm. gari BCC 24369, HADH productivity under a non-sterile condition (858 ± 12 U/g cell biomass) was comparable to that under a sterile condition (878 ± 15 U/g cell biomass). These results demonstrate the feasibility and simplicity of HADH production using Nnm. gari BCC 24369 under a non-sterile condition without compromising enzyme yield and any changes in Km value.

Optimization of selective production media for enhanced production of xylanases in submerged fermentation by Thielaviopsis basicola MTCC 1467 using L16 orthogonal array

Enzymes have been the centre of attention for researchers/industrialists worldwide due to their wide range of physiological, analytical, food/feed and industrial based applications. Among the enzymes explored for industrial applications, xylanases play an instrumental role in food/feed, textile/detergent, paper and biorefinery based application sectors. This study deals with the statistical optimization of xylanase production by Thielaviopsis basicola MTCC 1467 under submerged fermentation conditions using rice straw, as sole carbon source. Different fermentation parameters such as carbon source, nitrogen source, inorganic salts like KH2PO4, MgSO4 and pH of the medium were optimized at the individual and interactive level by Taguchi orthogonal array methodology (L16). All selected fermentation parameters influenced the enzyme production. Rice straw, the major carbon source mainly influenced the production of xylanase (~34 %). After media optimization, the yield of enzyme improved from 38 to ~60 IU/ml (161.5 %) indicating the commercial production of xylanase by T. basicola MTCC 1467. This study shows the potential of T. basicola MTCC 1467 for the efficient xylanase production under the optimized set of conditions.

Purification and Characterization of Haloalkaline, Organic Solvent Stable Xylanase from Newly Isolated Halophilic Bacterium-OKH

A novel, alkali-tolerant halophilic bacterium-OKH with an ability to produce extracellular halophilic, alkali-tolerant, organic solvent stable, and moderately thermostable xylanase was isolated from salt salterns of Mithapur region, Gujarat, India. Identification of the bacterium was done based upon biochemical tests and 16S rRNA sequence. Maximum xylanase production was achieved at pH 9.0 and 37°C temperature in the medium containing 15% NaCl and 1% (w/v) corn cobs. Sugarcane bagasse and wheat straw also induce xylanase production when used as carbon source. The enzyme was active over a range of 0-25% sodium chloride examined in culture broth. The optimum xylanase activity was observed at 5% sodium chloride. Xylanase was purified with 25.81%-fold purification and 17.1% yield. Kinetic properties such as Km and Vmax were 4.2 mg/mL and 0.31 μmol/min/mL, respectively. The enzyme was stable at pH 6.0 and 50°C with 60% activity after 8 hours of incubation. Enzyme activity was enhanced by Ca(2+), Mn(2+), and Mg(2+) but strongly inhibited by heavy metals such as Hg(2+), Fe(3+), Ni(2+), and Zn(2+). Xylanase was found to be stable in organic solvents like glutaraldehyde and isopropanol. The purified enzyme hydrolysed lignocellulosic substrates. Xylanase, purified from the halophilic bacterium-OKH, has potential biotechnological applications.

Optimization of recombinant hexaoligochitin-producing chitinase production with response surface methodology

Hexaoligochitin produced by chitinase, ASCHI61, from Aeromonas schubertii was recently expressed. In this work, the optimal conditions for the mass production of ASCHI61 were investigated. The efficiency of recombinant protein expression in Escherichia coli was determined by various parameters, including the pH of the culture medium, induction temperature, shaking speed, inducer concentration, and induction period. The optimization experiments could be simplified through a statistical design of experiments (response surface methodology). From the fractional factorial design, the interactive effect of induction temperature and time was the most significant. The total activity of the enzyme was 32,092 U at 23.9 °C with 115 min of induction. Under those conditions, the total activity of the recombinant protein was 30,650 U in the fermentation experiments, with an error of only 4.8%. The total activity of ASCHI61 increased 1.54-fold under the optimal conditions. Based on the results, ASCHI61 can be expressed more for hexaoligochitin production.

Cell culture medium improvement by rigorous shuffling of components using media blending

A novel high-throughput methodology for the simultaneous optimization of many cell culture media components is presented. The method is based on the media blending approach which has several advantages as it works with ready-to-use media. In particular it allows precise pH and osmolarity adjustments and eliminates the need of concentrated stock solutions, a frequent source of serious solubility issues. In addition, media blending easily generates a large number of new compositions providing a remarkable screening tool. However, media blending designs usually do not provide information on distinct factors or components that are causing the desired improvements. This paper addresses this last point by considering the concentration of individual medium components to fix the experimental design and for the interpretation of the results. The extended blending strategy was used to reshuffle the 20 amino acids in one round of experiments. A small set of 10 media was specifically designed to generate a large number of mixtures. 192 mixtures were then prepared by media blending and tested on a recombinant CHO cell line expressing a monoclonal antibody. A wide range of performances (titers and viable cell density) was achieved from the different mixtures with top titers significantly above our previous results seen with this cell line. In addition, information about major effects of key amino acids on cell densities and titers could be extracted from the experimental results. This demonstrates that the extended blending approach is a powerful experimental tool which allows systematic and simultaneous reshuffling of multiple medium components.

Statistical optimization of microalgae Pavlova lutheri cultivation conditions and its fermentation conditions by yeast, Candida rugopelliculosa

In this study, sequential strategy based design was applied to optimize the microalgae, Pavlova lutheri mass culture conditions and fermentation conditions of the cultured algae by proteolytic yeast Candidia rugopelliculosa to obtain small peptide chains. This optimization of culture and fermentation conditions by response surface methodology (RSM) finally leads to effective purification of a bioactive peptide MPGPLSPL (793.01 Da) with hydroxyl radical scavenging activity. Collectively, these results indicated that microalgae P. lutheri can enhance the hydroxyl radical inhibiting effect through protein hydrolysis process under RSM optimal condition.

Production of lignocellulolytic enzymes and enhancement of in vitro digestibility during solid state fermentation of wheat straw by Phlebia floridensis

Degradation by white rot fungi has the potential to increase digestibility of wheat straw and thus improve its value as animal feed. To optimize conditions for production of lignocellulolytic enzymes by Phlebia floridensis during solid state fermentation of wheat straw along with enhancement of in vitro digestibility, a response surface methodology (RSM) based experiment was designed. Effect of moisture content, inorganic nitrogen source (NH(4)Cl) and malt extract on lignocellulolytic enzymes, changes in chemical constituents and digestibility of wheat straw was evaluated. With increase in moisture content, laccase production increased up to 34-fold, while Manganese peroxidase was optimally produced in the presence of almost equal amount (50-55 mg/g of WS) of NH(4)Cl and malt extract. These supplements also significantly (p<0.05) enhanced the production of CMCase and xylanase. In vitro digestibility was increased by almost 50% with a loss of 27.6% and 14.6% in lignin and total organic matter, respectively. The present findings revealed P. floridensis to be an efficient organism for lignocellulolytic enzymes production and simultaneous enhancement in in vitro digestibility of wheat straw.

Marinimicrobium haloxylanilyticum sp. nov., a new moderately halophilic, polysaccharide-degrading bacterium isolated from Great Salt Lake, Utah

A new moderately halophilic, strictly aerobic, Gram-negative bacterium, strain SX15(T), was isolated from hypersaline surface sediment of the southern arm of Great Salt Lake (Utah, USA). The strain grew on a number of carbohydrates and carbohydrate polymers such as xylan, starch, carboxymethyl cellulose and galactomannan. The strain grew at salinities ranging from 2 to 22% NaCl (w/v). Optimal growth occurred in the presence of 7-11% NaCl (w/v) at a temperature of 35°C and a pH of 6.7-8.2. Major whole-cell fatty acids were C16:0 (30.5%), C18:0 (14.8%), C18:1ω7c (13.1%) and C12:0 (7.8%). The G+C content of the DNA was 60 ± 0.5 mol%. By 16S rRNA gene sequence analysis, strain SX15(T) was shown to be affiliated to members of the gammaproteobacterial genus Marinimicrobium with pair wise identity values of 92.9-94.6%. The pheno- and genotypic properties suggest that strain SX15(T) represents a novel species of the genus Marinimicrobium for which the name Marinimicrobium haloxylanilyticum is proposed. The type strain is SX15(T) (= DSM 23100(T) = CCUG 59572(T)).

Application of Plackett–Burman experimental design and Doehlert design to evaluate nutritional requirements for xylanase production by Alternaria mali ND-16

The objective of this study was to use statistically based experimental designs for the optimization of xylanase production from Alternaria mali ND-16. Ten components in the medium were screened for nutritional requirements. Three nutritional components, including NH(4)Cl, urea, and MgSO(4), were identified to significantly affect the xylanase production by using the Plackett-Burman experimental design. These three major components were subsequently optimized using the Doehlert experimental design. By using response surface methodology and canonical analysis, the optimal concentrations for xylanase production were: NH(4)Cl 11.34 g L(-1), urea 1.26 g L(-1), and MgSO(4) 0.98 g L(-1). Under these optimal conditions, the xylanase activity from A. mali ND-16 reached 30.35 U mL(-1). Verification of the optimization showed that xylanase production of 31.26 U mL(-1) was achieved.

Statistical optimization of thermo-tolerant xylanase activity from Amazon isolated Bacillus circulans on solid-state cultivation

A 2(2) factorial design was performed to find the best conditions of pH and temperature for xylanolytic activity of Bacillus circulans BL53 isolated from the Amazon environment. Solid-state cultivation was carried out on an inexpensive, abundant agro-industrial soybean residue. The central composite design (CCD) used for the analysis of treatment combinations showed that a second-order polynomial regression model was in good agreement with experimental results, with R(2) = 0.9369 (P < 0.05). The maximum activity was obtained at a high temperature (80 degrees C) and over a large pH range (4.0-7.0). Enzymatic activity was maintained in heated extracts up to 50 degrees C, suggesting that the xylanases of B. circulans BL53 are thermo-tolerant biocatalysts, being of interest for industrial processes. The crude enzyme extract hydrolyzed rice straw, sugar cane bagasse and soybean fiber and its activity was stimulated by Co(2+), Fe(3+), and beta-mercaptoethanol but inhibited by Mn(2+), Cu(2+), Ca(2+), Zn(2+), Ba(2+), Mg(2+) and by EDTA.