The Effect of Cultivation Conditions on Antifungal and Maize Seed Germination Activity of Bacillus-Based Biocontrol Agent.

Aflatoxin contamination is a global risk and a concerning problem threatening food safety. The biotechnological answer lies in the production of biocontrol agents that are effective against aflatoxins producers. In addition to their biocontrol effect, microbial-based products are recognized as efficient biosolutions for plant nutrition and growth promotion. The present study addresses the characterization of the representative of Phaseolus vulgaris rhizosphere microbiome, Bacillus sp. BioSol021, regarding plant growth promotion traits, including the activity of protease, cellulase, xylanase, and pectinase with the enzymatic activity index values 1.06, 2.04, 2.41, and 3.51, respectively. The potential for the wider commercialization of this kind of product is determined by the possibility of developing a scalable bioprocess solution suitable for technology transfer to an industrial scale. Therefore, the study addresses one of the most challenging steps in bioprocess development, including the production scale-up from the Erlenmeyer flask to the laboratory bioreactor. The results indicated the influence of the key bioprocess parameters on the dual mechanism of action of biocontrol effects against the aflatoxigenic Aspergillus flavus, as well on maize seed germination activity, pointing out the positive impact of high aeration intensity and agitation rate, resulting in inhibition zone diameters of 60 mm, a root length 96 mm, and a shoot length 27 mm.

Biosynthesis of lipase by Burkholderia cenocepacia ST8 using waste cooking oil as feedstock

Aims@#Every year, an estimated 25 million tons of waste oil are produced worldwide, and the generation of waste oil is one of the biggest global environmental problems. The incorporation of oil as a substrate for lipase production has been studied and shown to have a positive impact on its production. Burkholderia sp. is one of the major lipase-producing bacteria with their ability in bioremediation of oil-contaminated soil. This study aims to compare the production of lipase by Burkholderia cenocepacia ST8 using waste cooking oil and unused cooking oil as feedstock.@*Methodology and results@#The effect of different types of waste cooking oil (sunflower oil and palm oil) and concentration (1-3%) of waste cooking oil, agitation speed (100-400 rpm) and initial dissolved oxygen concentration (10-50%) on lipase production by B. cenocepacia ST8 under batch fermentation mode were investigated. The major fatty acids of which had been consumed were determined using gas chromatography. Results showed that 2% (v/v) of single used sunflower cooking oil produced the highest lipase activity of 138.86 U/mL with a productivity of 2.10 U/mL/h; agitation speed of 300 rpm produced the highest lipase activity of 183.56 U/mL with a productivity of 3.06 U/mL/h while 30% initial concentration of dissolved oxygen produced a lipase activity of 176.45 U/mL with a productivity of 2.94 U/mL/h. Oleic acid and linoleic acid were found to be the most consumed by B. cenocepacia ST8 among other fatty acids. @*Conclusion, significance and impact of study@#This study shows that 2% (v/v) single used sunflower cooking oil was the better type and optimum concentration of carbon source for the production of lipase by the fermentation of B. cenocepacia under 300 rpm and 30% initial concentration dissolved oxygen. The incorporation of 2% (v/v) single used sunflower cooking oil may be a great alternative to reduce the cost for the production of lipase as well as reducing the amount of waste oil generation.

Progressive freeze concentration of skimmed milk in an agitated vessel: Effect of the coolant temperature and stirring rate on process performance.

The aim of this study was to investigate the freeze-concentration of skimmed milk by a progressive freeze concentration process. The progressive freeze concentration procedure was performed at three different temperatures (-5, -10, and -15 ℃) and stirring rates (0, 500, and 1000 r/min). The solids concentration was determined and used for calculations of the efficiency of the process, concentrated yield, and experimental results validation. A general linear model was applied to determine the influence of the two factors studied, namely coolant temperature and agitation speed. In all tests, it was possible to concentrated skimmed milk with total solids content higher (P < 0.05) than ultra-high temperature skimmed milk. The highest concentration (P < 0.05) was achieved at low coolant temperature (-15 ℃) and high agitation speed (1000 r/min). The coolant temperature and the stirring rate both had a significant effect (P < 0.05) on the results of efficiency of the process and concentrated yield. Nevertheless, the parameter that showed the most significant effect in our study was the stirring rate. The tests presented a good fit since the root mean square values were below 25%. The freezing point temperatures of the concentrated milk fractions were lower than that of skimmed milk. Finally, the best-operating conditions in our study were achieved using a high coolant temperature (-5 ℃) and high mechanical stirring (1000 r/min), which was also the variable with the lowest (P < 0.05) retention of solids in the ice fraction. In our study, the progressive freeze concentration technique showed promise as an alternative for the dairy industry since it makes the development of new dairy products possible.

Kinetic modeling of bacteriocin-like inhibitory substance secretion by Pediococcus acidilactici Kp10 and its stability in food manufacturing conditions.

This paper deliberates the modelling and validation of bacteriocin-like inhibitory substance (BLIS) secretion by Pediococcus acidilactici Kp10 at different agitation speeds in a stirred tank bioreactor. A range of models namely the re-parameterised logistic, Luedeking-Piret and maintenance energy were assessed to predict the culture performance of the said bacterium. Growth of P. acidilactici Kp10 was enhanced with increased agitation speed up to 600 rpm while BLIS secretion was maximum at 400 rpm but decreased at higher agitation speed. Growth of P. acidilactici aptly subscribed to the re-parameterised logistic model while BLIS secretion and lactose consumption fitted well with the Luedeking-Piret model. The models revealed a relationship between growth of the bacterium and BLIS secretion. Bacterial growth and BLIS secretion were largely affected by the agitation speed of the stirred tank bioreactor which regulated the oxygen transfer to the culture. BLIS secretion by P. acidilactici Kp10 was however enhanced in oxygen-limited culture. The study also assessed BLIS from the perspective of its stability when subjected to factors such as temperature, pH and detergents. Results showed that BLIS produced by this strain was not affected by heat (at 25-100 °C for 20 min and at 121 °C for 15 min), surfactant (Tween 40, 60 and 80 and urea), detergents (up to 1% SDS), organic solvents (50% each of acetone, methanol and ethanol) and stable in a wide range of pH (2-10). The above information are pertinent with reference to commercial applications of this bacterial product in food manufacturing which invariably involve various sterilization processes and subjected to a wide pH range.

Analysis of Cleaning Process for Several Kinds of Soil by Probability Density Functional Method.

A method of analyzing the detergency of various soils by assuming normal distributions for the soil adhesion and soil removal forces was developed by considering the relationship between the soil type and the distribution profile of the soil removal force. The effect of the agitation speed on the soil removal was also analyzed by this method. Washing test samples were prepared by soiling fabrics with individual soils such as particulate soils, oily dyes, and water-soluble dyes. Washing tests were conducted using a Terg-O-Tometer and four repetitive washing cycles of 5 min each. The transition of the removal efficiencies was recorded in order to calculate the mean value (µrl) and the standard deviation (σrl) of the removal strength distribution. The level of detergency and the temporal alteration in the detergency can be represented by µrl and σrl, respectively. A smaller σrl indicates a smaller increase in the detergency with time, which also indicates the existence of a certain amount of soil with a strong adhesion force. As a general trend, the values of σrl were the greatest for the oily soils, followed by those of the water-soluble soils and particulate soils in succession. The relationship between the soil removal processes and the soil adhesion force was expressed on the basis of the transition of the distribution of residual soil. Evaluation of the effects of the agitation speed on µrl and Æ¡rl showed that σrl was not affected by the agitation speed; the value of µrl for solid soil and oily soil increased with increasing agitation, and the µrl of water-soluble soil was not specifically affected by the agitation speed. It can be assumed that the parameter Æ¡rl is related to the characteristics of the soil and the adhesion condition, and can be applied to estimating the soil removal mechanism.

Experimental and computational determination of the hydrodynamics of mini vessel dissolution testing systems.

Mini vessel dissolution testing systems consist of a small-scale 100-mL vessel with a small paddle impeller, similar to the USP Apparatus 2, and are typically utilized when only small amounts of drug product are available during drug development. Despite their common industrial use, mini vessels have received little attention in the literature. Here, Computational Fluid Dynamics (CFD) was used to predict velocity profiles, flow patterns, and strain rate distribution in a mini vessel at different agitation speeds. These results were compared with experimental velocity measurements obtained with Particle Image Velocimetry (PIV). Substantial agreement was observed between CFD results and PIV data. The flow is strongly dominated by the tangential velocity component. Secondary flows consist of vertical upper and lower recirculation loops above and below the impeller. A low recirculation zone was observed in the lower part of the vessel. The radial and axial velocities in the region just below the impeller are very small especially in the innermost core zone below the paddle, where tablet dissolution occurs. Increasing agitation speed reduces the radius of this zone, which is always present at any speed, and only modestly increases the tangential flow intensity, with significant implication for dissolution testing in mini vessels.

Investigating the influence of pH, temperature and agitation speed on yellow pigment production by Penicillium aculeatum ATCC 10409.

In this study, the combined effect of pH, temperature and agitation speed on yellow pigment production and mycelial growth of Penicillium aculeatum ATCC 10409 was investigated in whey media. Different pH levels (5, 6.5 and 8), temperatures (25, 30 and 35°C) and agitation speed levels (100 and 150 rpm) were tested to determine the best conditions to produce a fungal yellow pigment under submerged fermentation. The best production of yellow pigment (1.38 g/L) was obtained with a pH value of 6.5, a temperature of 30°C and an agitation speed of 150 rpm. In contrast, the maximal biomass concentration (11.12 g/L) was obtained at pH value of 8, a temperature of 30°C and an agitation speed of 100 rpm. These results demonstrated that biomass and yellow pigment production were not directly associated. The identification of the structure of unknown P. aculeatum yellow pigment was detected using UV absorption spectrum and FT-IR spectroscopy.

Ultrasound assisted production of a fibrinolytic enzyme in a bioreactor.

The present work illustrates ultrasound assisted production of a fibrinolytic enzyme at 1L bioreactor scale from Bacillus sphaericus MTCC 3672. To alleviate the shortcomings of one factor at a time method of optimization, central composite rotatable design of response surface methodology was employed for optimization of ultrasound assisted production. Different process parameters such as irradiation time, duty cycle and power of ultrasound were varied in 3 different levels in 11 experimental runs. For evaluating mass transfer enhancement effect of ultrasonication on production, control non sonicated fermentation was optimized by varying different agitation speed (300-500rpm) and aeration rate (8.33-33.33cc/s). Optimized ultrasonication protocol resulted in 1.48-fold increase in fibrinolytic enzyme yield as compared to non sonicated fermentation, which comprised of ultrasound irradiation at 25kHz for 10min with 40% duty cycle and 160W power on 12h of growth phase in 1L bioreactor operated at 400rpm agitation speed and 16.66cc/s aeration rate. Declined glucose concentration from 0.1% w/v (non sonicated control run) to 0.05% w/v and breakage of cells cluster emphasized on increased substrate utilization potential and enhanced convection of ultrasound assisted fermentation in a bioreactor. Deliverables of current studies will provide significant insights for enhancement of productivity of various enzymes at a bioreactor level.

Rhamsan gum production by Sphingomonas sp. CGMCC 6833 using a two-stage agitation speed control strategy.

Varying the agitation speed could greatly affect rhamsan gum production by Sphingomonas sp. CGMCC 6833. Batch fermentations at agitation speeds of 400, 600, 800, and 1,000 rpm were therefore carried out. The time course of specific cell growth rate, specific glucose consumption rate, and specific rhamsan gum formation rate was subsequently determined. Based on the results, a novel two-stage agitation speed control strategy was developed. From 0 to 13 H, the high specific cell growth and glucose consumption rates were achieved by setting the agitation speed of the fermenter at 800 rpm. From 13 H onward to the end of fermentation, the glucose consumption rate and specific cell growth rate were high at the agitation speed of 600 rpm. Using this method, the maximum concentration and productivity of rhamsan gum reached 21.63 ± 1.76 g L(-1) and 0.338 ± 0.028 g L(-1)  H(-1) , respectively, which were both higher than the optimum results obtained at constant agitation speeds.