The Use of Chitosan for Flocculation Recovery of Bacillus Biomass Grown on Dairy and Wine Industry Effluents

The downstream processing of efficient biomass-based microbial biopesticides is heavily reliant on obtaining the largest concentration of viable cells in the most cost-effective manner. The goal of this research was to assess the ability of chitosan flocculation to recover bacterial Bacillus sp. BioSol021 biomass from the broth after biological treatment of wastewaters from the dairy and wine industries. Second-order factorial design models were used to estimate the effect of chitosan concentration and mixing speed on flocculation efficiency, settling velocity, and antimicrobial activity against Aspergillus flavus, i.e., inhibition zone diameter. Response surface methodology was followed by multi-objective optimization by applying the desirability function (DF) and genetic algorithm (GA). The optimum values for flocculation efficiency, settling velocity, and inhibition zone diameter for cheese whey effluent were 88%, 0.10 mm/s, and 51.00 mm, respectively. In the case of winery flotation effluent, the optimum values were flocculation efficiency 95% and settling velocity 0.05 mm/s, while the inhibition zone diameter was 48.00 mm. These results indicate that utilizing chitosan as a flocculation agent not only fits the criteria for effective downstream processing, but also has a synergistic effect on Bacillus sp. antibacterial activity.

Dairy and Wine Industry Effluents as Alternative Media for the Production of Bacillus-Based Biocontrol Agents

Food industry effluents represent one of the major concerns when it comes to environmental impact; hence, their valorization through different chemical and biological routes has been suggested as a possible solution. The vast amount of organic and inorganic nutrients present in food industry effluents makes them suitable substrates for microbial growth. This study suggests two valorization routes for whey as dairy industry effluent and flotation wastewater from the wine industry through microbial conversion to biocontrol agents as value-added products. Cultivations of the biocontrol strain Bacillus sp. BioSol021 were performed in a 16 L bioreactor to monitor the bioprocess course and investigate bioprocess kinetics in terms of microbial growth, sugar substrate consumption and surfactin synthesis, as an antimicrobial lipopeptide. The produced biocontrol agents showed high levels of biocontrol activity against mycotoxigenic strains of Aspergillus flavus, followed by a significant reduction of sugar load of the investigated effluents by the producing microorganisms. With proven high potential of whey and winery flotation wastewater to be used as substrates for microbial growth, this study provides grounds for further optimization of the suggested valorization routes, mostly in terms of bioprocess conditions to achieve maximal techno-economical feasibility, energy saving and maximal reduction of effluents' organic and inorganic burden.

Taguchi Grey Relational Analysis for Multi-Response Optimization of Bacillus Bacteria Flocculation Recovery from Fermented Broth by Chitosan to Enhance Biocontrol Efficiency

Degradation of environment is a challenge to crop production around the world. Biological control of various plant diseases using antagonistic bacteria is an encouraging alternative to traditionally used chemical control strategies. Chitosan as a well-known natural flocculation agent also exhibits antimicrobial activity. The goal of this study was to investigate a dual nature of chitosan in flocculation of Bacillus sp. BioSol021 cultivation broth intended for biocontrol applications. Experiments were performed based on L₁₈ standard Taguchi orthogonal array design with five input parameters (chitosan type and dosage, pH value, rapid and slow mixing rates). In this study, the grey relational analysis was used to perform multi-objective optimization of the chosen responses, i.e., flocculation efficiency and four inhibition zone diameters against the selected phytopathogens. The results have indicated a great potential of a highly efficient method for removal of the Bacillus bacteria from the cultivation broth using chitosan. The good flocculation efficiency and high precipitate antimicrobial activity against the selected phytopathogens were achieved. It has been shown that multiple flocculation performance parameters were improved, resulting in slightly improved response values.

Utilization of waste glycerol for the production of biocontrol agents nigericin and niphimycin by Streptomyces hygroscopicus: bioprocess development

Search for more environment-friendly methods for controlling plant diseases that would contribute to the goal of sustainability in agriculture is in focus. In the present study, the potential of Streptomyces hygroscopicus isolated from soil sample in the production of biocontrol agents, nigericin and niphimycin, effective against Alternaria alternata storage apple pathogen was examined. Also, modelling and optimization of medium composition for biocontrol agent biosynthesis was performed. The results showed that the optimum amount of C₃H₈O₃, (NH₄)₂SO₄ and K₂HPO₄ in the medium for Streptomyces hygroscopicus biosynthesis is 20, 0.25 and 1.46 g/L, respectively. Scale-up and validation of the obtained results performed in the 3 L laboratory-scale bioreactor showed that on the optimized medium at an aeration rate of 0.7 vvm and an agitation speed of 200 rpm, produced nigericin and niphimycin, showed high activity. Under the same conditions, cultivation of S. hygroscopicus was performed in a 7 L laboratory bioreactor in a medium with waste glycerol instead of pure glycerol. Results showed that the methanol extract of S. hygroscopicus cultivation liquid, containing nigericin and niphimycin, was high effective against two Alternaria isolates. This was confirmed in vitro by obtaining large inhibition zone diameters on A. alternata KA10 (47 mm) and T1Jg₃ (44.33 mm) isolates. After successful in vitro analysis, in planta testing was performed. It was found that necrosis diameters that were measured on artificially inoculated apple fruits with A. alternata compared to necrosis diameter measured on untreated, control fruits, were 4.47 and 3.56 times smaller.

Kenics Static Mixer Combined with Gas Sparging for the Improvement of Cross-Flow Microfiltration: Modeling and Optimization

The use of membrane filtration as a downstream process for microbial biomass harvesting is hampered due to the low permeate flux values achieved during the microfiltration of fermentation broths. Several hydrodynamic methods for increasing permeate flux by creating turbulent flow patterns inside the membrane module are used to overcome this problem. The main goal of this study was to investigate the combined use of a Kenics static mixer and gas sparging during cross-flow microfiltration of Bacillus velezensis IP22 cultivation broth. Optimization of the microfiltration process was performed by using the response surface methodology. It was found that the combined use of a static mixer and gas sparging leads to a considerable increase in the permeate flux, up to the optimum steady-state permeate flux value of 183.42 L·m−2·h−1 and specific energy consumption of 0.844 kW·h·m−3. The optimum steady-state permeate flux is almost four times higher, whilst, at the same time, the specific energy consumption is almost three times lower compared to the optimum results achieved using gas sparging alone. The combination of Kenics static mixer and gas sparging during cross-flow microfiltration is a promising technique for the enhancement of steady-state permeate flux with simultaneously decreasing specific energy consumption.

Modeling and Optimization of Gas Sparging-Assisted Bacterial Cultivation Broth Microfiltration by Response Surface Methodology and Genetic Algorithm

Production of highly efficient biomass-based microbial biopesticides significantly depends on downstream processing in terms of obtaining as high concentration of viable cells as possible. Microfiltration is one of the recommended operations for microbial biomass separation, but its main limitation is permeate flux decrease due to the membrane fouling. The effect of air sparging as a hydrodynamic technique for improvement of permeate flux during microfiltration of Bacillus velezensis cultivation broth was investigated. Modeling of the microfiltration was performed using the response surface methodology, while desirability function approach and genetic algorithm were applied for optimization, i.e., maximization of permeate flux and minimization of specific energy consumption. The results have revealed antagonistic relationship between the investigated dependent variables. The optimized values of superficial feed velocity and transmembrane pressure were close to the mean values of the investigated value ranges (0.68 bar and 0.96 m/s, respectively), while the optimized value of superficial air velocity had a more narrow distribution around 0.25 m/s. The results of this study have revealed a significant improvement of microfiltration performance by applying air sparging, thus this flux improvement method should be further investigated in downstream processing of different bacterial cultivation broths.

Dynamic Modeling Using Artificial Neural Network of Bacillus Velezensis Broth Cross-Flow Microfiltration Enhanced by Air-Sparging and Turbulence Promoter

Cross-flow microfiltration is a broadly accepted technique for separation of microbial biomass after the cultivation process. However, membrane fouling emerges as the main problem affecting permeate flux decline and separation process efficiency. Hydrodynamic methods, such as turbulence promoters and air sparging, were tested to improve permeate flux during microfiltration. In this study, a non-recurrent feed-forward artificial neural network (ANN) with one hidden layer was examined as a tool for microfiltration modeling using Bacillus velezensis cultivation broth as the feed mixture, while the Kenics static mixer and two-phase flow, as well as their combination, were used to improve permeate flux in microfiltration experiments. The results of this study have confirmed successful application of the ANN model for prediction of permeate flux during microfiltration of Bacillus velezensis cultivation broth with a coefficient of determination of 99.23% and absolute relative error less than 20% for over 95% of the predicted data. The optimal ANN topology was 5-13-1, trained by the Levenberg-Marquardt training algorithm and with hyperbolic sigmoid transfer function between the input and the hidden layer.

Production of plant protection agents in medium containing waste glycerol by Streptomyces hygroscopicus: Bioprocess analysis

The surplus of waste glycerol, by-product of the biodiesel production process, is available at the global market. Some species of the genera Streptomyces have the ability to assimilate glycerol and convert it into valuable metabolic products. In the present study, the ability of Streptomyces hygroscopicus to assimilate waste glycerol and convert it into metabolic compounds with antifungal activity against four phytopathogenic fungi obtained from apple fruit samples expressing rot symptoms, was investigated. Production of antifungal metabolites by S. hygroscopicus was carried out in 3 l stirred tank bioreactor through 7 days. Fermentation was carried out at 27 °C with aeration rate of 1.5 vvm and agitation rate of 100 r.p.m. The aim of this work was to analyse bioprocess parameters and to determine at which stage of bioprocess the production of antifungal metabolites occurs. Activity of the cultivation liquid on two isolates of Alternaria alternata and two isolates of Fusarium avenaceum were determined every 12 h using in vitro well diffusion method. It was found that the maximum production of antifungal metabolites occurred at 108 hour of cultivation. Formed inhibition zones have shown that the produced antifungal metabolites have high efficacy on tested phytopathogenic fungi (inhibition zone diameter higher than 35 mm for all test organisms).

Dynamic Modeling of Streptomyces hygroscopicus Fermentation Broth Microfiltration by Artificial Neural Networks

Artificial neural networks (ANNs) have been used to dynamically model cross-flow microfiltration of Streptomyces hygroscopicus fermentation broths. The aim is to predict permeate flux as a function of temperature, feed flow, transmembrane pressure and processing time. Dynamic modeling of microfiltration performance of complex systems (such as broths) is very important for design of new processes and better understanding of the present. The results of ANN model analysis suggest that the coefficients of the determination have high values. The application of the Bayesian regularization gave better results to the performance of the neural network compared to the Levenberg-Marquet algorithm. The optimal number of neurons in the hidden layer is eight. Analysis of the absolute relative error showed excellent permeate flux estimates for 100 % of the data points, with an error less than 5 % for the data obtained during microfiltration in the presence of a turbulence promoter. Whilst in the case of microfiltration without turbulence promoter 90 % of predictions have an error less than 10 %. The results of applying the concept of neural networks in the dynamic modeling of microfiltration of Streptomyces hygroscopicus fermentative broths with and without a turbulence promoter clearly show the validity of proposed method for simulation and prediction of microfiltration experimental results.

Artemisinin Story from the Balkans

The isolation is reported of artemisinin (qinghaosu), a drug remarkably effective against malaria, from the aerial parts of Artemisia annua L. (sweet wormwood) at the Department of Chemistry, University of Belgrade (now Faculty of Chemistry), Serbia by the end of 1970, almost two years before the isolation of the same compound in China.

CR-100 synthetic zeolite adsorption characteristics toward Northern Banat groundwater ammonia

The adsorption characteristics of synthetic zeolite CR-100 in a fixed-bed system using continuous flow of groundwater containing elevated ammonia concentration were examined. The possibilities for adsorbent mass calculation throughout mass transfer zone using novel mathematical approach as well as zeolite adsorption capacity at every sampling point in time or effluent volume were determined. The investigated adsorption process consisted of three clearly separated steps indicated to sorption kinetics. The first step was characterized by decrease and small changes in effluent ammonia concentration vs. experiment time and quantity of adsorbed ammonia per mass unit of zeolite. The consequences of this phenomenon were showed in the plots of the Freundlich and the Langmuir isotherm models through a better linear correlation according as graphical points contingent to the first step were not accounted. The Temkin and the Dubinin-Radushkevich isotherm models showed the opposite tendency with better fitting for overall measurements. According to the obtained isotherms parameter data, the investigated process was found to be multilayer physicochemical adsorption, and also that synthetic zeolite CR-100 is a promising material for removal of ammonia from Northern Banat groundwater with an ammonia removal efficiency of 90%.

[OBSTETRIC SEPSIS]

Obstetric sepsis is still a significant cause of maternal mortality in developing world, and in the last decade, an increasing number of cases have also been recorded in developed countries. Its onset can be insidious and patients can deteriorate from well-being to development of septic shock with multiple organ dysfunction syndrome and death in a few hours. Unfortunately, some deaths are unavoidable, but early diagnosis and prompt therapy can improve outcome and survivability.

[Duodenal polyps of gastric origin]

Recently, thanks to the collected knowledge and increased diagnostic abilities we more often meet the diseases that have been considered very seldom. Beside that, we form the new assumptions that must be proved. Today, more often we meet gastric mucosa in duodenum. That according to some researchers, introduces a real possibility for appearance of the polyps, ulcers or cancer on gastric substratum. In the subject patient the two polyps of the gastric origin were found in a duodenum. That could support the assumption that ectopic gastric mucosa presents one of the real possibilities for appearance of polyps, ulcers and cancer.