Solid State Fermentation Reactor Research Articles

Solid state fermentation for the production of γ-decalactones by Yarrowia lipolytica

Abstract The production of γ-decalactones as aroma compounds is highly dependent on the access of the biocatalyst to substrate and co-substrate (oxygen). In this work, the potential of solid state fermentation (SSF) is investigated for this production with Y. lipolytica W29. Luffa sponge was used as an inert support and the investigation focused on the impact of aeration on metabolites. In that goal, experiments were carried out in three different SSF reactor types, wide-mouth Erlenmeyer flask (static aeration), forced aeration mini-reactor, and small-headspace bottle (without aeration). Four lactones were detected by GC–MS during the degradation of ricinoleic acid from castor oil by Y. lipolytica W29: 3-hydroxy-γ-decalactone, which reached the high concentration of 5 g/L (in wide-mouth Erlenmeyer flask), γ-decalactone, dec-2-en-4-olide and dec-3-en-4-olide. In this study, some yeast cells changed their morphological properties from the yeast-like shape to pseudo-mycelium and mycelium. These cells may undergo a metabolic shift resulting in the high production of 3-hydroxy-γ-decalactone. The yield of lactone in the small-headspace bottle was very low suggesting insufficient oxygen availability. For their part, forced-aeration conditions in mini-reactors resulted in the stripping of lactone compounds. From the present work, an alternative process is proposed as a novel model for lactone production.

A novel strategy for producing compost with enhanced biopesticide properties through solid-state fermentation of biowaste and inoculation with Bacillus thuringiensis

In the framework of a circular economy, organic solid wastes are considered to be resources useful for obtaining value-added products. Among other potential uses, biodegradable wastes from agricultural, industrial, and domestic sources are being studied to obtain biopesticides through solid-state fermentation (SSF), mainly at the laboratory scale. The suitability of biowaste (source-selected organic fraction of municipal solid waste) for use as a substrate for Bacillus thuringiensis (Bt) growth under non-sterile conditions in a 10 L SSF reactor was determined in this study. An operational strategy for setting up a semi-continuous process yielding a stabilised organic compost-like material enriched with Bt suitable for use as a soil amendment was developed. Concentrations of 1.7·107–2.2·107 and 1.3·107–2.1·107 CFU g−1 DM for Bt viable cells and spores, respectively, were obtained in the final material. As the results confirmed, Bt-enriched compost-like material with potential biopesticide properties can be produced from non-sterile biowaste.

A new two-phase kinetic model of sporulation of Clonostachys rosea in a new solid-state fermentation reactor

A new two-phase kinetic model of sporulation of Clonostachys rosea in a new solid-state fermentation (SSF) reactor was proposed. The model including exponential and logistic models was applied to study the simultaneous effect of temperature, initial moisture content, medium thickness and surface porosity of the plastic membrane on C. rosea sporulation. The model fits experimental data very well and allows accurate predictions of spore production. The maximum spore production achieved 3.360×1010 (spores/gDM), about 10 times greater than that in traditional SSF reactor(data not shown). The new reactor can provide two times sporulation surface area. Moisture content can be adjusted by changing the surface porosity to meet the spore production. Two mixings carried out during fermentation makes medium loose and results in a mass of new sporulation surface area. Therefore, the new SSF reactor would have great potential for application in bulk spore production of fungal biocontrol agents.

Modeling the Ripening Degree and Bioreactor Design of Tulum Cheese Ripening by Penicillium Roqueforti Immobilized in Solid-State Bioreactor

ABSTRACTModeling the ripening degree and bioreactor design was done for tulum cheese fermentation in batch-packed solid state fermentation (SSF) processes by using toxic and nontoxic strains of Penicillium roqueforti. Water soluble protein and ripening degree were evaluated to determine the bioreactor performances. The calculated kinetic constants and the statistical analysis showed that the batches of SSF reactor ripened with nontoxic strains of P. roqueforti at 12 °C gave the highest values of soluble protein and, consequently, ripening degree and highest productivity yield. The highest productivity yield of ripening degree was recorded in SSF reactor with a lipid content of 6.45%, acidity of 0.64%, pH of 6.29 and nontoxic strains of P. roqueforti at 12 °C.

Dynamic Modelling and Experimental Validation of a Solid State Fermentation Reactor

A mathematical model is presented that predicts the non-isothermal dynamical behavior of a pilot-plant Solid State Fermentation (SSF) fed-batch reactor, employed in the preparation of compost for the Agaricus bisporus mushroom cultivation. The 9-ODE first-principles lumped-parameter model describes microbial growth, substrate consumption, compost solid and liquid volumetric fractions as well as bulk temperature and air humidity. The biomass is divided into 3 broad families with different macro-kinetics: mesophilic bacteria and fungi that may inhibit the A. bisporus growth, thermophilic fungi associated to the growth selectivity of A. bisporus and thermophilic actinobacteria degrading lignocellulose. Free-convection and evaporative heat transfer are included in the energy balance. Kinetic parameters were adjusted using a sensitivity analysis. The resulting model reproduces accurately the temperature profiles of the pilot-plant SSF reactor for different initial conditions and predicted final microflora concentration ratios are within expected values.

Solid state fermentation of lipopeptide antibiotic iturin A by using a novel solid state fermentation reactor system

A new solid state fermentation reactor (SSFR) for solid substrate was used for the production of lipopeptide antibiotic iturin A using Bacillus subtilis RB14-CS. Solid state fermentation (SSF) is the technique of cultivation of microorganisms on solid and moist substrates in the absence of free water. SSF has shown much promise in the development of several bioprocesses and products because of their several advantages like absence of free water that allows simplified downstream processing and low cost. SSFR allows agitation of the SSF culture with improved temperature control and air supply. Interestingly, when okara, the widely available waste product from the tofu industries, was used as the solid substrate for the SSFR, no iturin A production was observed. However, without agitation, production of iturin A was observed in the SSFR but the production level remained low. The low production of iturin A was found to be due to the heat generation and excess temperature rise inside the reactor system during the fermentation process. Maintaining the temperature within a range of 25–30°C, production of iturin A was significantly improved in the SSFR. This was comparable to the laboratory scale production, and signifies the potential application of the SSFR for SSF.

Optimization of washing rate in a hybrid recycling system of solid state and submerged fermentation

The feasibility has been shown for a novel hybrid system of solid state fermentation (SSF) with recycle for organic solid waste in which a part of solid is washed to suppress accumulation of glue-like material and resulting reaction breakdown. The optimum washing rate in the SSF reactor was examined. The water content and pH in the SSF reactors were also monitored throughout the operation. The decomposition rate of the reactors at 187.5 and 250 ml/day maintained the high value. These reactors reached a near steady state at 0.07 g VM/(g VM day) at constant rate. Washing conditions less than these rates resulted in breakdown of the reaction. A decrease of decomposition rate was observed in drier conditions of <40% of water content and a good correlation between decomposition rate constant and water content in the SSF reactor was observed.

A novel hybrid system of solid state and submerged fermentation with recycle for organic solid waste treatment

A new concept to hybridize solid state fermentation (SSF) and submerged fermentation (SmF) reactors by introducing a system that recycles the substrate is described. Two separate experiments were conducted to examine the effects of including a wash cycle in the SSF reactor, and introducing a recycling process for the excess sludge from the SmF reactor. After 25 days, both experiments reached a steady state of ∼170 g(volatile material, VM) day −1 decomposition rate which was compatible to a loading rate of 186 gVM day −1 under the conditions used. The SSF reactor alone decomposed 92% of the total organic load with the introduction of the recycling system. A reduction of 10 times in the size/volume of the proposed system was achieved compared to the conventional activated sludge method. These experiments confirmed the feasibility of the new system proposed.

Solid state fermentation reactors: From lab scale to pilot plant

Relatively many workers in the world are studying different aspects in SSF processes but few are working on reactor design and scale-up. From about 10 years, we are developing reactors from lab scale to pilot plant, based on the same technology, reactor design and flowsheet to allow fermentation with a deep layer (up to 1 m in the pilot plant). These reactors have all a forced aeration and the possibility or not to agitate. Regulations of temperature and water content of the culture are monitored by a special device.

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.