Use of response surface methodology for optimizing process parameters for high inulinase production by the marine yeast Cryptococcus aureus G7a in solid-state fermentation and hydrolysis of inulin

Evaluation of carbon sources for the production of inulinase by Aspergillus niger A42 and its characterization

Inulinases are used for the production of high-fructose syrup and fructooligosaccharides, and are widely utilized in food and pharmaceutical industries. In this study, different carbon sources were screened for inulinase production by Aspergillus niger in shake flask fermentation. Optimum working conditions of the enzyme were determined. Additionally, some properties of produced enzyme were determined [activation (E_a)/inactivation (E_ia) energies, Q₁₀ value, inactivation rate constant (k_d), half-life (t_1/2), D value, Z value, enthalpy (ΔH), free energy (ΔG), and entropy (ΔS)]. Results showed that sugar beet molasses (SBM) was the best in the production of inulinase, which gave 383.73 U/mL activity at 30 °C, 200 rpm and initial pH 5.0 for 10 days with 2% (v/v) of the prepared spore solution. Optimum working conditions were 4.8 pH, 60 °C, and 10 min, which yielded 604.23 U/mL, 1.09 inulinase/sucrase ratio, and 2924.39 U/mg. Additionally, E_a and E_ia of inulinase reaction were 37.30 and 112.86 kJ/mol, respectively. Beyond 60 °C, Q₁₀ values of inulinase dropped below one. At 70 and 80 °C, t_1/2 of inulinase was 33.6 and 7.2 min; therefore, inulinase is unstable at high temperatures, respectively. Additionally, t_1/2, D, ΔH, ΔG values of inulinase decreased with the increase in temperature. Z values of inulinase were 7.21 °C. Negative values of ΔS showed that enzymes underwent a significant process of aggregation during denaturation. Consequently, SBM is a promising carbon source for inulinase production by A. niger. Also, this is the first report on the determination of some properties of A. niger A42 (ATCC 204,447) inulinase.

Recent advances in bio-based multi-products of agricultural Jerusalem artichoke resources

The Jerusalem artichoke is a perennial plant that belongs to the sunflower family. As a non-grain crop, Jerusalem artichoke possesses a number of desirable characteristics that make it a valuable feedstock for biorefinery, such as inulin content, rapid growth, strong adaptability, and high yields. This review provides a comprehensive introduction to renewable Jerusalem artichoke-based biomass resources and recent advances in bio-based product conversion. Furthermore, we discuss the latest in the development of inulinase-producing microorganisms and enhanced inulin hydrolysis capacity of microbes by genetic engineering, which lead to a more cost-effective Jerusalem artichoke biorefinery. The review is aimed at promoting Jerusalem artichoke industry and new prospects for higher value-added production.

Purification and Characterization of an Endoinulinase from Xanthomonas campestris pv. phaseoli KM 24 Mutant

An extracellular endoinulinase from Xanthomonas campestris pv. phaseoli KM 24 mutant was purified to homogeneity by gel filtration chromatography and showed a specific activity of 119 U/mg. The optimum pH and temperature of the purified enzyme were found to be 6.0 and 50 °C, respectively. The enzyme was stable up to 60 °C, retaining 60% of residual activity for 30 min, but inactivated rapidly above 60 °C. The enzyme was found to be stable at pH=6-9 when it retained 100% of its residual activity. The Lineweaver-Burk plot showed that the apparent Km and vmax values of the inulinase when using inulin as a substrate were 1.15 mg/mL and 0.15 µM/min, respectively, whereas the kcat value was found to be 0.145 min-1. The calculated catalytic efficiency of the enzyme was found to be 0.126 (mg·min)/mL. The purified inulinase can be used in the production of high fructose syrups.

Optimization, kinetics, and modeling of inulinase production by K. marxianus var. marxianus

Pressmud, a by-product from the sugarcane industry, was used as a carbon source for the production of inulinase in solid-state fermentation (SSF). Statistical experimental designs were employed to screen the nutrients and optimize the media composition for the production of inulinase by Kluyveromyces marxianus var. marxianus. Eighteen various nutrients were selected for preliminary screening of production medium component by Plackett-Burman design (PBD) technique. Five nutrients were found to be significant for inulinase production and they were optimized by central composite design (CCD). The optimal media components for solid-state fermentation of inulinase using pressmud were (g/gds): corn steep liquor, 0.06072; urea, 0.01916; beef extract, 0.00957; FeSO4 · 7H2O, 0.00013; K2HPO4, 0.00441. The effect of moisture content and substrate concentration was also studied. From the results it was found that a maximum inulinase activity of 288 U/gds occurs at the moisture content of 65% and substrate concentration of 10 g. The constants in the Michaelis-Menten equation were evaluated and a high R (2) value implied the fitness of the model. Artificial neural network (ANN) modeling was also employed to predict the inulinase production.

Enhanced inulinase production by Streptomyces sp. in solid state fermentation through statistical designs

In this work, inulinase was produced by solid state fermentation by Streptomyces sp. using copra waste as carbon source. The nutrients were screened by Plackett-Burman design. From the pareto chart it was found that the nutrients, namely, soya bean cake, MgSO4·7H2O and (NH4)2SO4 were found to be most significant nutrient components. Hence, these three components were selected for further optimization using central composite design (CCD) in response surface methodology (RSM). The optimum conditions were soya bean cake: 0.05711 g/gds, MgSO4·7H2O: 0.00063 g/gds and (NH4)2SO4: 0.00772 g/gds. Under these optimized conditions, the production of inulinase was found to be 131 U/gds. The constants in the Michaelis-Menten equation were evaluated and high R2 value implies the fitness of the model.

Optimization of inulinase production by a newly isolated Aspergillus tubingensis CR16 using low cost substrates

Production of an extracellular, thermostable inulinase was carried out by a newly isolated strain of Aspergillus tubingensis CR16 using wheat bran and corn steep liquor (CSL) under solid state fermentation (SSF). Response surface methodology (RSM) involving Box Behnken design (BBD) was employed for the optimization of process parameters viz. time period of fermentation, % moisture content, inoculum size and pH of the medium. Maximum yield of inulinase was 257±11.4 U/g, obtained by inoculating 5 g of wheat bran with 10(9) spores/ml, at initial 71.2% moisture content and pH 6.1 after 103 h of fermentation along with 1358.6±0.8 U/g of invertase activity. Crude inulinase showed maximum activity at 60 °C and pH 5.0. The enzyme was found to be thermostable retaining about 90% of its activity for 4.5 h at 60 °C. Fructose was produced as an end product of inulin hydrolysis proving that the enzyme produced was exoinulinase.

Fructanase and fructosyltransferase activity of non-Saccharomyces yeasts isolated from fermenting musts of Mezcal

Fructanase and fructosyltransferase are interesting for the tequila process and prebiotics production (functional food industry). In this study, one hundred thirty non-Saccharomyces yeasts isolated from "Mezcal de Oaxaca" were screened for fructanase and fructosyltransferase activity. On solid medium, fifty isolates grew on Agave tequilana fructans (ATF), inulin or levan. In liquid media, inulin and ATF induced fructanase activities of between 0.02 and 0.27U/ml depending of yeast isolate. High fructanase activity on sucrose was observed for Kluyveromyces marxianus and Torulaspora delbrueckii, while the highest fructanase activity on inulin and ATF was observed for Issatchenkia orientalis, Cryptococcus albidus, and Candida apicola. Zygosaccharomyces bisporus and Candida boidinii had a high hydrolytic activity on levan. Sixteen yeasts belonging to K. marxianus, T. delbrueckii and C. apicola species were positive for fructosyltransferase activity. Mezcal microbiota proved to showed to be a source for new fructanase and fructosyltransferases with potential application in the tequila and food industry.

Bioprocessing data for the production of marine enzymes

This review is a synopsis of different bioprocess engineering approaches adopted for the production of marine enzymes. Three major modes of operation: batch, fed-batch and continuous have been used for production of enzymes (such as protease, chitinase, agarase, peroxidase) mainly from marine bacteria and fungi on a laboratory bioreactor and pilot plant scales. Submerged, immobilized and solid-state processes in batch mode were widely employed. The fed-batch process was also applied in several bioprocesses. Continuous processes with suspended cells as well as with immobilized cells have been used. Investigations in shake flasks were conducted with the prospect of large-scale processing in reactors.

Process optimization for the production of diosgenin with Trichoderma reesei

Based on the response surface methodology, an effective microbial system for diosgenin production from enzymatic pretreated Dioscorea zingiberensis tubers with Trichoderma reesei was studied. The fermentation medium was optimized with central composite design (3(5)) depended on Plackett-Burmann design which identified significant impacts of peptone, K(2)HPO(4) and Tween 80 on diosgenin yield. The effects of different fermentation conditions on diosgenin production were also studied. Four parameters, i.e. incubation period, temperature, initial pH and substrate concentration were optimized using 4(5) central composite design. The highest diosgenin yield of 90.57% was achieved with 2.67% (w/v) of peptone, 0.29% (w/v) of K(2)HPO(4), 0.73% (w/v) of Tween 80 and 9.77% (w/v) of substrate, under the condition of pH 5.8, temperature 30 degrees C. The idealized incubation time was 6.5 days. After optimization, the product yield increased by 33.70% as compared to 67.74 +/- 1.54% of diosgenin yield in not optimized condition. Scale-up fermentation was carried out in a 5.0 l bioreactor, maximum diosgenin yield of 90.17 +/- 3.12% was obtained at an aeration of 0.80 vvm and an agitation rate of 300 rpm. The proposed microbial system is clean and effective for diosgenin production and thus more environmentally acceptable than the traditional acid hydrolysis.

Inulinase-expressing microorganisms and applications of inulinases

In this review article, inulinase-expressing microorganisms and its potential applications in transformation of inulin into very-high-fructose syrup, bioethanol, and inulooligosaccharides are overviewed. In the past 10 years, many new inulinase producers have been obtained and many genes encoding inulinases from different microorganisms have been cloned and characterized. Some novel processes for exoinulinase overproduction have been developed for bioethanol production and ultra-high-fructose syrup. The endoinulinases have also been used for production of inulooligosaccharides from inulin and inulin-containing materials.