The effect of phosphate concentration on phytase production and the reduction of phytic acid content in canola meal by Aspergillus carbonarius during a solid-state fermentation process

The use of canola meal, an abundant side-product of canola oil processing in Canada, as animal feed is hampered by high phytic acid levels that reduce metal cation availability. Aspergillus carbonarius grows well in a solid canola meal medium, produces phytase and reduces the phytic acid content to zero. Inorganic phosphate addition at a concentration of 1 mg and 5 mg/110 g solid-state culture system results in better growth of the microorganism, higher rates and levels of phytase production, and faster reduction of phytic acid content. Phosphate concentrations of 50mg and 100 mg/110 g inoculated system had a negative effect affecting primarily the initial rates of biomass and phytase production and phytic acid content reduction. Models that predict biomass production (expressed as glucosamine content) and phytase, as well as the reduction of phytic acid content in the solid-state cultures supplemented with phosphate are reported. They fit the experimental results reasonably well (with a maximum deviation of 7%).     

Phytase production and decrease of phytic acid content in canola meal byAspergillus carbonarius in solid-state fermentation

Solid-state fermentation (SSF) usingAspergillus carbonarius with canola meal as a substrate showed that production of phytase was associated with growth; maximum activity was achieved after 72 h. Apparent 25% and 10% increases in the protein content of the canola meal were noticed after 48 h and 72 h, respectively but total carbohydrate concentration had fallen by 25% by the end of fermentation. The rate of decrease of phytic acid content was optimum with a moisture content between 53% and 60%; homogenization of the inoculum for 120 s led to the greatest biomass and lowest phytic acid content. Inoculation of sterile meal led to lower phytic acid contents than inoculation of non-sterile meal.The authors are with the Department of Chemical Engineering, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada     

Reduction of phytic acid content in canola meal by Aspergillus ficuum in solid state fermentation process

Summary Solid state fermentation (SSF) of canola meal has been carried out to reduce its phytic acid content using Aspergillus ficuum NRRL 3135. In certain batches, a complete reduction of phytic acid content in canola meal was achieved in 48 h. A larger amount of biomass in the inoculum and older inoculum increased the rate of phytic acid hydrolysis. The optimum moisture content of the medium was found to be 67% for phytic acid hydrolysis in an SSF process. The substitution of water in the semi-solid medium with acetate buffer resulted in faster reduction of the phytic acid content. A 15% increase in the amount of protein after 120 h of incubation was observed in the treated meal. The crude phytase preparation extracted from the canola meal after it was treated in an SSF process was also used for reduction of the phytic acid content in new batches of canola meal both in semi-solid medium and in liquid medium. In the semi-solid medium, 58% of the phytic acid was hydrolysed at 45°C in 20 h, while 100% hydrolysis was recorded at 50°C in 12 h in the liquid medium. The SSF process seems to be beneficial for the upgrading of canola meal by reducing both its phytic acid content and increasing the amount of protein.Offprint requests to: Z. Duvnjak     

Phytic acid content reduction in canola meal by various microorganisms in a solid state fermentation process

Solid state fermentation of canola meal has been carried out for the reduction of its phytic acid content using the following microorganisms: Rhizopus oligosporus NRRL 2990, Aspergillus niger NRC 5765 and NRC 401 121, Aspergillus ficuum NRRL 3135 and a wild Saccharomyces cerevisiae strain. The results showed that all these microorganisms can be used for the reduction of the phytic acid content in the tested material. A. ficuum which completely hydrolyzed the phytic acid in 48 hours was the most efficient. Buffered systems, aeration and an increase in inoculum concentration caused faster and higher reduction of phytic acid content in canola meal.     

Beneficial effect of protracted sterilization of lentils on phytase production by Aspergillus ficuum in solid state fermentation

Water addition to the solid substrate preceding autoclaving increased substrate porosity and phytase production in solid state fermentation. In comparison with dry sterilization, the phytase activity increased 6‐, 8.5‐, and 10‐fold when the autoclaving time was 20, 40, and 60 min, respectively. Autoclaving increased the void space of sterilized lentils, and the increase was 16% higher when water was supplemented to the lentils before sterilization. Image analysis of SEM pictures of the solid substrate showed that water supplementation presterilization portended greater micro‐fissure surface area, which also increased with increasing the sterilization time. SEM pictures of the fermentation product showed that fungal growth into the center of the solid substrate was ubiquitous when water was supplemented before sterilization but was absent when water was supplemented post sterilization. Similarly, spore formation on the substrate surface for the presterilization water supplementation samples far exceeded spore formation for samples that received supplementation poststerilization. This evidence suggests that improved mass transfer into the solid substrate resulting from additional pore volume and the formation of micro‐fissures on the substrate surface is responsible for the observed gains in phytase productivity in solid state fermentation. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Effect of water activity on exo-pectinase production byAspergillus niger CH4 on solid state fermentation

Summary Ethylene glycol, sorbitol and glycerol were used as water activity depressors to study the effect of water activity on pectinase production byAspergillus niger CH4. Ethylene glycol depressed a_w without supporting growth nor strongly affecting pectinase production in petri dish cultures. This depressor was used to evaluate the influence of water activity on exo-pectinase production by SSF. It was found that although pectinase production decreased at low a_w values, this activity was present at a_w values as low as 0.90. The specific activity increased up to 4.5 fold by reducing a_w from 0.98 to 0.90. The reducing groups accumulated extracellularly suggesting sugar transport limitation as a consequence of a_w depression.     

Effect of substrate moisture content on fungal production of citric acid in a solid state fermentation system

Summary Under solid state fermentation conditions, the production of citric acid byAspergillus niger varied considerably with the initial moisture content of apple pomace. The stimulating effect of methanol on fungal production of citric acid decreased markedly as the substrate moisture decreased.     

Sclerotia growth and carotenoid production of Penicillium sp PT95 during solid state fermentation of corn meal

Using corn meal as fermentation substrate, the effect of some factors, fermentation time and supplementation of saccharide and nitrogen sources as well as vegetable oil, on the sclerotia growth and carotenoid production of Penicillium sp PT95 during solid state fermentation were studied. When PT95 strain was grown on the amended medium by supplementing of 3g NaNO3, 10g maltose and 2.5g soybean oil per liter of salt solution to basal medium for 20 days, the dry sclerotia weight and carotenoid yield reached 9.70 g and 5260 g / 100 g of substrate, respectively. Without supplementation only 5.36g dry sclerotia and 2149g carotenoid / 100 g of substrate was attained. © Rapid Science Ltd. 1998     

Beneficial effects of Rhizopus oligosporus fermentation on reduction of glucosinolates, fibre and phytic acid in rapeseed (Brassica napus) meal

Solid state fermentation was employed using Rhizopus oligosporus to develop a fermented product from rapeseed meal (RSM). The contents of glucosinolates, thiooxazolidones, phytic acid and crude fibre declined by 43.1%, 34%, 42.4% and 25.5%, respectively, following inoculation with R. oligosporus. Fermentation also increased nitrogen and protein contents of the meal. This study may open a new prospective for a simple and cost effective technique for reduction of toxicants in RSM.     

Potential of fed-batch culture in solid state fermentation for production of gibberellic acid

Summary Fed-batch culture technique, applied to the solid state fermentation process for the production of gibberellic acid, improves the yield by 18.2% as compared to a conventional batch solid state fermentation.     

Optimization of mycophenolic acid production in solid state fermentation using response surface methodology

Mycophenolic acid (MPA) can be produced in solid state fermentation. An isolate of Penicillium brevi-compactum ATCC 16024 grown on moist wheat bran produced a titre of 425 mg per kg of wheat bran. Central composite rotatable design and response surface methodology were employed to derive a statistical model for media optimization towards production of mycophenolic acid. Five levels with a five factorial design were adopted. The correlation coefficient was 0.82, ensuring a satisfactory adjustment of the model to the experimental values. This statistical design was very effective in improving the titre of mycophenolic acid up to 3286 mg per kg of wheat bran. Received 24 July 1998/ Accepted in revised form 4 December 1998     

Influence of the glycolytic rate on production of citric acid and oxalic acid by Aspergillus niger in solid state fermentation

A study was performed to understand the physiology and biochemical mechanism of citric acid accumulation during solid state fermentation of sweet potato using Aspergillus niger Yang No.2. A low citrate-producing mutant was isolated followed by a comparative study of the fermentation process and selected physiological and biochemical parameters. In contrast with the parent strain, the mutant strain displayed lower concentrations, yields and production rates of citric acid, accompanied by higher concentrations, yields and production rates of oxalic acid. In addition, the mutant utilized starch at a lower rate although higher concentrations of free glucose accumulated in the cultures. Biochemical analyses revealed lower rates of glucose uptake and hexokinase activity of the mutant strain in comparison with the parent strain. It is proposed that, in common with submerged fermentation, over-production of citric acid in solid state fermentation is related to an increased glucose flux through glycolysis. At low glucose fluxes, oxalic acid is accumulated.     

Impact of process parameters on chitinase production by an alkalophilic marine Beauveria bassiana in solid state fermentation

A chitinolytic fungus, Beauveria bassiana was isolated from marine sediment and significant process parameters influencing chitinase production in solid state fermentation using wheat bran were optimised. The organism was strongly alkalophilic and produced maximum chitinase at pH 9·20. The NaCl and colloidal chitin requirements varied with the type of moistening medium used. Vegetative (mycelial) inoculum was more suitable than conidial inoculum for obtaining maximal enzyme yield. The addition of phosphate and yeast extract resulted in enhancement of chitinase yield. After optimisation, the maximum enzyme yield was 246·6 units g⁻¹ initial dry substrate (U gIDS⁻¹). This is the first report of the production of chitinase from a marine fungus.     

Optimization studies on the production of cyclosporin A by solid state fermentation

Several parameters including (a) tray fermentation with and without perforation (b) thickness of solid substrate bed (c) type of inoculum (d) size of inoculum (e)?effect of relative humidity were studied for the optimum production of Cyclosporin A by solid state fermentation using Tolypocladium sp. The results indicate that while perforations in the trays had no significance on the yield of Cyc A, the other parameters had an influence on the production of Cyc A. The results indicate that under the optimized conditions, Cyc A can be produced in bulk quantities economically.     

Gluconic acid production by Aspergillus niger mutant ORS-4.410 in submerged and solid state surface fermentation

Aspergillus niger ORS-4.410, a mutant of Aspergillus niger ORS-4 was produced by repeated irradiation with UV rays. Treatments with chemical mutagnes also resulted into mutant strains. The mutants differed from the parent strain morphologically and in gluconic acid production. The relationship between UV treatment dosage, conidial survival and frequency of mutation showed the maximum frequency of positive mutants (25%) was obtained along with a conidial survival of 59% after second stage of UV irradiation. Comparison of gluconic acid production of the parent and mutant ORS-4.410 strain showed a significant increase in gluconic acid production that was 87% higher than the wild type strain. ORS-4.410 strain when transferred every 15 days and monitored for gluconic acid levels for a total period of ten months appeared stable. Mutant ORS-4.410 at 12% substrate concentration resulted into significantly higher i.e. 85-87 and 94-97% yields of gluconic acid under submerged and solid state surface conditions respectively. Further increase in substrate concentration appeared inhibitory. Maximum yield of gluconic acid was obtained after 6 days under submerged condition and decreased on further cultivation. Solid state surface culture condition on the other hand resulted into higher yield after 12 days of cultivation and similar levels of yields continued thereafter.     

The effect of temperature on the growth of A. niger in solid state fermentation

A kinetic model of solid state fermentation with temperature deactivation of microorganisms is presented. The experimental results of cultivation of Aspergillus niger on a mixture of wheat bran and beet pulp in temperature range from 26 °C to 40 °C were used to estimate the parameters of the model. The activation energies of growth, thermal deactivation and maintenance have been calculated.List of Symbols C _CX mol/g proportionality coefficient - E _d J/mol energy of activation for thermal deactivation - E _g J/mol energy of activation for growth - J _CO2 mol/gh carbon dioxide evolution rate - k _d h^–1 thermal deactivation constant - k _g h^–1 growth kinetic constant - k _x h^–1 net growth constant - m h^–1 maintenance coefficient - N _CO2 mol amount of carbon dioxide - N _{m, CO2} mol maximum amount of carbon dioxide generated by growth - t h time - X g dry biomass weight - X _m g maximum biomass weight - X dimensionless biomass weight - X _0,r g real mass of inoculum - X _0,a g apparent mass of inoculum - X ₀ dimensionless apparent mass of inoculum - dimensionless maintenance coefficient This work was supported by the Committee of Scientific Research under grant No 3 3401 91 02.     

A pilot process of solid state fermentation from sugar beet pulp for the production of microbial protein

The bioconversion of sugar beet pulp (SBP) into microbial protein by the process of solid state fermentation (SSF) was studied. Two SSF reactors (each having overall dimensions of 17.6 × 3.6 × 2.0 m) with appropriate control systems were constructed. This pilot plant has a maximum working capacity of 50 metric tons (20% dry metter). The production strain used was Aspergillus tamarii 827, which was isolated by our laboratory. The protein content of the products amounted to 22.4% in 48 h.     

Paecilomyces sp. ZB is a cell factory for the production of gibberellic acid using a cheap substrate in solid state fermentation

Gibberellic acid from the fungi has been widely used in agriculture. In this study, more than 20 fungal isolates were screened and Paecilomyces sp. ZB shown to produce more gibberellic acid than other fungal isolates. Cow dung was used as low cost substrate for gibberellic acid production in solid state fermentation (SSF). Carbon, nitrogen and ionic sources stimulated gibberellic acid production in SSF. Lactose emerged as the significant carbon source supporting more gibberellic acid production (731 µg/g). Among the nitrogen sources, glycine appeared to influence the production of more gibberellic acid (803 µg/g). The process parameters were optimized to enhance gibberellic acid production using a two-level full factorial design and response surface methodology. The amount of gibberellic acid production was influenced mainly by moisture and pH of the substrate. Gibberellic acid production was 1312 µg/g under the optimized conditions and the predicted response was 1339 µg/g. The gibberellic acid yield increased twofolds after medium optimization. The extracted gibberellic acid was sprayed on the growing Mung bean plant and it stimulated the growth of the plant effectively. To conclude, cow dung is a new alternative to produce gibberellic acid in SSF.     

Citric acid and polyols production by Aspergillus niger at high glucose concentration in solid state fermentation on inert support

Summary Aspergillus niger cultures at high initial glucose concentration (up to 400 g/1) on Amberlite as inert support were carried out. Citric acid was accumulated in the support showing high concentration (94.54 g/l) and productivity (1.35 g/l h) without inhibition related to the presence of metals (Mn²⁺, Zn²⁺, Co²⁺, Cu²⁺, and Ca²⁺) at high concentrations. Citric acid accumulation was clearly associated with both, glycerol production and to the age of the culture. Glycerol and erythritol, the major osmoregulator metabolites, were also produced (8.16 and 24.57 g/l respectively) at 400 g/l of glucose.