Culture Fermentation Process Research Articles

Optimization of the Culture Medium, Fermentation Process, and Effectiveness of a Biopesticide from an Iranian Bacillus thuringiensis var. tenebrionis (BN2)

Optimization of the Culture Medium, Fermentation Process, and Effectiveness of a Biopesticide from an Iranian Bacillus thuringiensis var. tenebrionis (BN2)

Nematicidal Activity of Cyclopiazonic Acid Derived From Penicillium commune Against Root-Knot Nematodes and Optimization of the Culture Fermentation Process.

Among 200 fungal strains isolated from the soil, only one culture filtrate of Aspergillus flavus JCK-4087 showed strong nematicidal activity against Meloidogyne incognita. The nematicidal metabolite isolated from the culture filtrate of JCK-4087 was identified as cyclopiazonic acid (CPA). Because JCK-4087 also produced aflatoxins, six strains of Penicillium commune, which have been reported to be CPA producers, were obtained from the bank and then tested for their CPA productivity. CPA was isolated from the culture filtrate of P. commune KACC 45973. CPA killed the second-stage juveniles of M. incognita, M. hapla, and M. arearia with EC50–3 days 4.50, 18.82, and 60.51 μg mL–1, respectively. CPA also significantly inhibited egg hatch of M. incognita and M. hapla after a total of 28 days of treatment with the concentrations > 25 μg mL–1. The enhancement of CPA production by P. commune KACC 45973 was explored using an optimized medium based on Plackett–Burman design (PBD) and central composite design (CCD). The highest CPA production (381.48 μg mL–1) was obtained from the optimized medium, exhibiting an increase of 7.88 times when compared with that from potato dextrose broth culture. Application of the wettable power-type formulation of the ethyl acetate extract of the culture filtrate of KACC 45973 reduced gall formation and nematode populations in tomato roots and soils under greenhouse conditions. These results suggest that CPA produced by P. commune KACC 45973 can be used as either a biochemical nematicide or a lead molecule for developing chemical nematicides to control root-knot nematodes.

Analysis of Sour Porridge Microbiota and Improvement of Cooking Quality via Pure Culture Fermentation Using Lacticaseibacillus paracasei Strain SZ02.

The microbial composition of sour porridge at different fermentation times was analyzed through high-throughput sequencing, and a pure culture fermentation process was established to optimize production process and improve the edible quality of the porridge. In natural fermentation, Firmicutes and Proteobacteria were abundant throughout the process. Specifically, Aeromonas, Acinetobacter, and Klebsiella were dominant on fermentation days 1–5 (groups NF-1, NF-3, and NF-5), while Lactobacillus and Acetobacter gradually became the dominant bacteria on fermentation day 7 (group NF-7). Further, we isolated one strain of acid-producing bacteria from sour porridge, identified as Lacticaseibacillus paracasei by 16SrRNA sequencing and annotated as strain SZ02. Pure culture fermentation using this strain significantly increased the relative starch and amylose contents of the porridge, while decreasing the lipid, protein, and ash contents (P < 0.05). These findings suggest that sour porridge produced using strain SZ02 has superior edible qualities and this strategy may be exploited for its industrial production.

Life cycle assessment of bacterial cellulose production

Bacterial cellulose (BC), obtained by fermentation, is an innovative and promising material with a broad spectrum of potential applications. Despite the increasing efforts towards its industrialization, a deeper understanding of the environmental impact related to the BC production process is still required. This work aimed at quantifying the environmental, health, and resource depletion impacts related to a production of BC. An attributional life cycle assessment (LCA) was applied to a process design of production of BC, by static culture, following a cradle-to-gate approach. The LCA was modeled with GaBi Pro Software using the ReCiPe 2016 (H) methodology with environmental impact indicators at midpoint level. The functional unit was defined as 1 kg of BC (dry mass), in 138.8 kg of water. From the total used resources (38.9 ton/kg of BC), water is the main one (36.1 ton/kg of BC), most of which (98%) is returned to fresh waters after treatment. The production of raw materials consumed 17.8 ton of water/kg of BC, 13.8 ton/kg of BC of which was for the production of carton packaging, culture medium raw materials, and sodium hydroxide (for the washing of BC). The remaining consumed water was mainly for the fermentation (3.9 ton/kg) and downstream process (7.7 ton/kg). From the identified potential environmental impacts, the production of raw materials had the highest impact, mainly on “Climate change”, “Fossil depletion”, “Human toxicity, non-cancer”, and “Terrestrial toxicity”. The sodium dihydrogen phosphate production, used in the culture medium, showed the highest environmental impacts in “Human toxicity, non-cancer” and “Terrestrial ecotoxicity”, followed by corn syrup and carton production. The static culture fermentation and downstream process showed impact in “Climate change” and “Fossil depletion”. Per se, the BC production process had a small contribution to the consumption of resources and environmental impact of the BC global life cycle.

Research advances on arachidonic acid production by fermentation and genetic modification of Mortierella alpina.

Arachidonic acid (ARA, 5, 8, 11, 14-cis-eicosatetraenoic acid) is a relevant ω-6 polyunsaturated fatty acid, which plays essential roles in human immune, cardiovascular, and nervous systems. It is widely used in medicine, cosmetics, nutrition, and other fields. Traditionally, ARA is obtained from animal tissues. However, due to the limitation and unsustainability of existing resources, microorganisms are a potential alternative resource for ARA production. In this regard, major efforts have been made on algae and filamentous fungi, among which Mortierella alpina is the most effective strain for industrial ARA production. In this review, we summarized the recent progress in enhancing M. alpina production by optimization of culture medium and fermentation process and genetic modification. In addition, we provided perspectives in synthetic biology methods and technologies to further increase ARA production.

Application of Michaelis–Menten in the kinetics of oil palm frond enzymatic hydrolysis for ferulic acid production

Ferulic acid (FA) production has become a frequent focus on today’s research due to its antioxidant properties. However, there has been little to none studies reported on the usage of mixed culture as inoculum in FA production. This study aims to determine the kinetics FA production in a mixed culture fermentation by applying the Michaelis–Menten kinetic model. In this study, mixed culture fermentation process using oil palm frond bagasse (OPFB) as substrate was applied for FA production improvement. Optimum condition was applied to study ferulic acid esterase (FAE) mechanism for kinetic modelling purposes. The kinetic model used was based on the Michaelis–Menten kinetic model. Runge–Kutta Fourth Order method was used to solve the kinetic model. Maximum FAE activity was achieved at the 28 h of fermentation process at 3.7 × 10−3 mU mL−1. This result proved that enzymatic hydrolysis occurred during fermentation process. Kinetic study was conducted with Michaelis–Menten kinetic model used as a reference kinetic equation. Three kinetic constants, Vmax, Km and Ks were determined as 3.725 × 10−3 g L−1 h−1, 28.231 g L−1 and 1.33 × 10−2 h−1 respectively using Runge–Kutta Fourth Order approach. The outcome of this study confirms that the kinetics of the process fit well with the Michaelis–Menten model. This also suggests that the usage of mixed culture has the potential to induce enzymatic hydrolysis hence improving FA production from OPFB during fermentation process.

Screening of Penicillium Species and Optimisation of Culture Conditions for the Production of Ergot Alkaloids Using Surface Culture Fermentation Process

The present study deals with the screening of fungal species and suitable fermentation medium for the production of ergot alkaloids. Various species of genus Penicillium were grown on differentfermentation media by employing surface culture fermentation technique to achieve the most suitable medium and the best Penicillium sp. The results showed that medium M5 gave maximum yield withPenicillium commune. Different culture conditions such as effect of different carbon and nitrogen sources, their concentration levels, different pH values and sizes of inoculum on the production of ergot alkaloids were also studied to improve the yield. Maximum production of ergot alkaloids (4.32 mg/L) was achieved with 15 mL spore suspension at pH 5 in fermentation medium containing 35% (w/v) sucrose. All these results indicate that culture conditions are very much crucial to improve the yield of ergot alkaloids produced by Penicillium commune through surface culture process.

The chemostat study of metabolic distribution in extreme-thermophilic (70°C) mixed culture fermentation.

The effects of pH, hydrogen partial pressure (PH2), and influent glucose concentration on the metabolic distribution in chemostat were investigated in this work in extreme-thermophilic mixed culture fermentation (MCF) process. The results showed that acetate, ethanol, and hydrogen were the main metabolites. A shift of ethanol to acetate and hydrogen was observed as pH increasing from 4.0 to 7.0 or PH2 decreasing from 0.64 to 0.05 atm. The maximum hydrogen yield was 3.16 ± 0.16 mol/mol glucose at PH2 0.05 atm. Lactate was only accumulated at low pH or high influent glucose concentration, while others such as butyrate and formate were rather low. Thermodynamic analysis illustrated that a mixture of acetate, ethanol, and/or lactate was essential for hydrogen production in extreme-thermophilic MCF. The hydrogen-producing rate was also calculated, and the maximum value was 2.2 ± 0.1 L/(L-reactor/day) at PH2 0.05 atm. Except hydrogen, other metabolites, such as liquid fatty acids and biofuels, could also be the producing targets in extreme-thermophilic MCF.

Functional Properties of Pediococcus Species Isolated from Traditional Fermented Cereal Gruel and Milk in Nigeria

Pediococcus species were isolated from ogi, fermented cow and sheep milk. Functional properties such as hydrogen peroxide production, tolerance to simulated gastric transit with pepsin and bile salts, bile salt hydrolytic (BSH) activity, in vitro adherence assay and antimicrobial characteristics were carried out. The strains tolerated bile salts and BSH activity was positive. Pediococcus acidilactici OB4 survived gastric transit after 180min comparable to a probiotic strain, L. acidophilus CNRZ1923. The strains exhibited good adhesion to the three extracellular matrices. Two isolates (P. acidilactici OB4 and P. pentosaceus SM3) produced bacteriocin. Bacteriocins were stable at pH 4-9 and on treatment with lipase, catalase, α-amylase and lysozyme, while their activity was lost on treatment with proteinase K, pronase E, pepsin and trypsin. The bacteriocins produced by P. pentosaceus SM3 was heat stable at 100°C for 10 min while P. acidilactici OB4 was stable at 100°C for 30 min. The bacteriocin produced by P. acidilactici OB4 was identified as PedA while P. pentosaceus SM3 was PedB. The bacteriocins had relative heat stability, high anti-listerial activity and a good spectrum of activity against some pathogenic microorganisms. The results demonstrated possible inclusion in a starter culture fermentation process of food and dairy products and safety characteristics.

Integrated Proteomic and Metabolomic Analysis of an Artificial Microbial Community for Two-Step Production of Vitamin C

An artificial microbial community consisted of Ketogulonicigenium vulgare and Bacillus megaterium has been used in industry to produce 2-keto-gulonic acid (2-KGA), the precursor of vitamin C. During the mix culture fermentation process, sporulation and cell lysis of B. megaterium can be observed. In order to investigate how these phenomena correlate with 2-KGA production, and to explore how two species interact with each other during the fermentation process, an integrated time-series proteomic and metabolomic analysis was applied to the system. The study quantitatively identified approximate 100 metabolites and 258 proteins. Principal Component Analysis of all the metabolites identified showed that glutamic acid, 5-oxo-proline, L-sorbose, 2-KGA, 2, 6-dipicolinic acid and tyrosine were potential biomarkers to distinguish the different time-series samples. Interestingly, most of these metabolites were closely correlated with the sporulation process of B. megaterium. Together with several sporulation-relevant proteins identified, the results pointed to the possibility that Bacillus sporulation process might be important part of the microbial interaction. After sporulation, cell lysis of B. megaterium was observed in the co-culture system. The proteomic results showed that proteins combating against intracellular reactive oxygen stress (ROS), and proteins involved in pentose phosphate pathway, L-sorbose pathway, tricarboxylic acid cycle and amino acids metabolism were up-regulated when the cell lysis of B. megaterium occurred. The cell lysis might supply purine substrates needed for K. vulgare growth. These discoveries showed B. megaterium provided key elements necessary for K. vulgare to grow better and produce more 2-KGA. The study represents the first attempt to decipher 2-KGA-producing microbial communities using quantitative systems biology analysis.

Screening for an oil‐removing microorganism and oil removal from waste silk by pure culture fermentation

AbstractThe presence of oil is the major limitation to the regeneration of spun silk from waste silk. A pure culture fermentation process was developed to remove oil from waste silk. Fourteen strains were isolated from natural fermentation liquor of waste silk. The strain D3 showed highest lipase activity and oil‐removing ability. This strain was identified as Rhodococcus sp. on the basis of morphological and biochemical characteristics and 16S rRNA sequence analysis. The strain D3 was used to remove oil from waste silk by pure culture fermentation. The effects of various parameters on oil removal were investigated. A pH of 7.0, a temperature of 35–40°C, an incubation time of three days and an inoculum of 10% were optimum conditions for removing oil from waste silk by stain D3. This study shows that pure culture fermentation is a promising process to improve the oil removal of waste silk.

Influence of the pH on (open) mixed culture fermentation of glucose: A chemostat study

Catabolic products from anaerobic fermentation processes are potentially of industrial interest. The volatile fatty acids and alcohols produced can be used as building blocks in chemical processes or applied directly as substrates in a mixed culture process to produce bioplastics. Development of such applications requires a predictable and controllable product spectrum of the fermentation process. The aim of the research described in this paper was (i) to investigate the product spectrum of an open mixed culture fermentation (MCF) process as a function of the pH, using glucose as substrate, and (ii) to relate the product spectrum obtained to generalized biochemical and thermodynamic considerations. A chemostat was operated under carbon and energy limitation in order to investigate the pH effect on the product spectrum in a MCF process. A transition from CO(2)/H(2) production at lower pH values to formate production at higher pH values was observed. The ratio of CO(2)/H(2) versus formate production was found to be related to the thermodynamics of formate dehydrogenation to CO(2)/H(2). This transition was associated with a shift in the catabolic products, from butyrate and acetate to ethanol and acetate, likely due to a decrease in the oxidation state of the electron carriers in the cell. The product spectrum of the MCF process as a function of the pH could largely be explained using general biochemical considerations.

A model for continuous fermentations with amylolytic yeasts

A two-stage, associative fermentation process is more effective for continuous yeast biomass production from starch than a single-stage mixed culture fermentation process. By operating two stages, competition for the same growth limiting substrate is reduced leading to efficient starch utilization. In this article, a mathematical model has been proposed for continuous, two-stage fermentation with a pure culture, amylolytic yeast in the first stage and a mixed culture second stage with a faster growing, nonamylolytic yeast. The model parameters were determined for Saccharomycopsis fibuligera and Candida utilis in continuous, single-stage, pure cultures. In the two-stage model, the effects of changes in dilution rate on biomass, amylase, reducing sugar, and starch concentration, and ratio of stage volumes on microbial composition are discussed and compared with experimental data.

Real Time Digital Multivariable Control for a Fermentation System

In this paper, the application of a real time optimal control algorithm to a continuos culture fermentation process is described. This algorithm can be applied to a certain class of discrete multivariable nonlinear systems. The process parameter variations problem is discussed and a control scheme usinα a real time identification algorithm is proposed. This algorithm allows the control always uses the real para-meter values leading to a very robust control structure.

Optimal Control of a Class of Discrete Multivariable Nonlinear Systems. Application to a Fermentation Process

The optimal control of a class of discrete multivariable nonlinear systems given by: xk+1 = a (xk) + B (xk) uk, yk = C xk, is analyzed. A closed-loop structure is obtained with the proposed performance index. The addition of numerical integrators to the output error and the design of an optimal control law for the resultant augmented system lead to a very robust control structure. The performance of this control law is evaluated by applying it to a simulated continuous culture fermentation process.

Optimal Control of a Class of Multivariable Nonlinear Systems. Application to a Fermentation Process

Controllability conditions and a control technique for a class of multivariable nonlinear systems are presented. The application to a continuous culture fermentation process is discussed. It is shown that an appropriate selection of a penalization function gives a control law that includes the conventional PI controller. The steady state error for the closed-loop system is zero and it is not sensitive to the process parameter variations in a neighbourhood of the controller parameters.