Production of Bacillus subtilis soil isolate as biocontrol agent under bioreactor conditions.

This study aimed to investigate the biomass production of Bacillus subtilis in flask and bioreactor conditions. It is necessary to carry the culture from the shake flask to the pH, air, temperature and stirring controlled bioreactor in order to reduce the working time and increase the production efficiency and product quality. In this study, Bacillus was isolated from soil and grown under flask and bioreactor conditions as biocontrol agent against Botrytis cinerea and Fusarium oxysporum. In this process, a pH value of 7.5, 100% O2 saturation, 30% dissolved O2, at the temperature of 37 °C, total flow of 0.1 Lmin-1 and mixing speed of 150 min-1 were preferred for optimal concerning high production yield of B. subtilis in bioreactor. To test whether B. subtilis has antifungal activity on the growth of B. cinerea and F. oxysporum, a dual culture assay in a PDA medium was carried out. Ultimately, high biomass production in a short incubation period by reaching 2.2 µg/mL after 9 h in the bioreactor. It was observed that the bacteria produced in the bioreactor cultivation grew stronger and showed high antifungal activity which resulted 33.33% inhibition percentage against B. cinerea. It was concluded that B. subtilis can be used as a green-fungicide against B. cinerea and F. oxysporum, and bacterial metabolites from B. subtilis could pave the way for the development of next generation green/biopesticides.

Optimization of Growth Conditions for the Production of Bacillus subtilis Using Central Composite Design and Its Antagonism Against Pathogenic Fungi.

Today, the enhancement of spore yields of Bacillus subtilis has considerable interest and has been widely investigated. In this context, studies have been carried out to improve the spore yield as well as the production amount. In order to perform this, optimization studies are conducted for large-scale production of B. subtilis in bioreactors. The prokaryotic structure, high extracellular production potential, lack of pathogenic activity, well-known fermentation technology and short fermentation time are the prominent advantages for the production of B. subtilis in a bioreactor. The Bacillus species produce a wide variety of antifungal and antimicrobial compounds, making them ideal biological control agents. In this study, first, the growth conditions of the medium were investigated and then optimized using the central composite design approach to achieve the highest productivity for the growth of B. subtilis. In the experiments, the effect of temperature of 25, 30 and 35 °C and pH level of 6.0, 7.0 and 8.0 on spore yield was studied. Moreover, the antifungal activity of the B. subtilis culture was investigated against pathogenic fungi: Colletotrichum gloeosporioides, Botrytis cinerea and Aspergillus brasiliensis.

Investigation of antimicrobial and mechanical effects of functional nanoparticles in novel dental resin composites.

OBJECTIVES: Imidazole and benzimidazole derivatives have recently attracted attention as remarkable materials due to their advantages in chemistry, pharmacology, and biomaterials. This article focuses on dental composites with azole functional groups incorporated to affect their physicochemical and mechanical properties and antibacterial activity. METHODS: Dental composites were fabricated by embedding the functionalized imidazole and benzimidazole nanoparticles into a Bis-GMA/TEGDMA matrix to form the imidazole and benzimidazole dental composites series (I and B). The material was produced through hand blending of the monomer (50:50, wt%), filler (0-30, wt%), and initiator combination (CQ/EDMAB:0.8:1.6, wt%), and LED light-curing unit for 60 s. RESULTS: Using various characterization techniques, I and B series were validated. The dental composites' approximate solubility and sorption significances were evaluated by conducting experiments on specific dental composite formulations. Fenton reaction test was performed to determine the chemical stability of the dental composites. The mechanical properties of the dental composites were investigated. Finally, by testing cell growth in the presence of composites, their antibacterial activities were determined. CONCLUSIONS: In this study, it was observed that the mechanical, physiochemical, and antibacterial properties of the functional azole-containing nanoparticles were positively improved by adding them to the structure of dental composites. These experimental results paved the way for the synthesized materials to be used in industrial applications. CLINICAL SIGNIFICANCE: Since the chemical, mechanical, and antimicrobial properties of dental composites containing 10% imidazole and benzimidazole functional nanoparticles are far superior, they constitute an excellent alternative for preventing dental caries and long-term use of dental composites.

Screening plant growth effects of sheep slaughterhouse waste-derived soil amendments in greenhouse trials.

Ameliorative effects of sheep slaughterhouse waste-derived soil amendments (struvite, blood meal, bone meal) were explored and quantified by a series of comparative greenhouse trials. A scoring matrix system was developed for 25 different test plants using 300 agricultural measurements obtained for three basic growth parameters (fresh-dry plant weights and plant heights) and four different fertilizer sources including solid vermicompost. More than 70% of NH4+-N recovery from sheep slaughterhouse wastewater was achieved using a chemical combination of MgCl2.6H2O + NaH2PO4.2H2O, a molar ratio of Mg2+:NH4+-N:PO43-P = 1.2:1:1, a reaction pH of 9.0, an initial NH4+-N concentration of 240 mg/L, and a reaction time of 15 min. According to SEM micrographs, surface morphology of struvite exhibited a highly porous structure composed of irregularly shaped crystals of various sizes (11.34-79.38 µm). FTIR spectroscopy verified the active functional groups on the proximity of all fertilizer sources within the spectral range of 500-3900 cm-1. TGA-DTG-DSC thermograms of struvite revealed that the mass loss occurred in two temperature regions and reached a maximum mass loss rate of 1.63%/min at 317 °C. The average percentages of increase (57.55-100.62%) and performance points (69-79) corroborated that the fertility value of struvite ranked first on average in cultivation of the analyzed plant species. Findings of this agro-valorization study confirmed that sheep slaughterhouse waste-derived fertilizers could be a beneficial way to promote bio-waste management and environmentally friendly agriculture.

Monitoring microalgal growth of Chlorella minutissima with a new all solid-state contact nitrate selective sensor.

As third generation feedstock, microalgae are microorganisms that can grow only in the optimum conditions. There are parameters including the concentration of macro and microelements in nutrient solution, pH, temperature and light intensity that have significant impact on microalgal growth. In recent years, various sensing devices have been developed for sensitive measurement of these parameters during microalgal growth. In this study, a new potentiometric nitrate selective sensor was developed to indicate the nitrate uptake of microalgae and the effect of nitrate nutrient on microalgal growth, specifically, and this sensor was successfully applied to determine nitrate concentration in medium during microalgal growth. Moreover, the effects of nitrate, carbonate and phosphate concentration in the growth medium on biomass production of Chlorella minutissima were investigated by using Box-Behnken design method, and optimum conditions were determined for the highest biomass production of microalgae. As a result of the experiments, it was seen that the highest C. minutissima production was achieved using the medium consist of 2.63 g/L NaNO3 , 0.35 g/L Na2 CO3 and 0.4 g/L KH2 PO4. Statistically, it was observed that there was a proportional relationship between the microalgae production and investigated parameters such as carbon, nitrogen and phosphate amounts of culture mediums. The electrode showed a wide linear range between 1.0 × 10-1 and 5.0 × 10-5  M with a detection limit of the 5 × 10-6  M and the response time was found as 10 s. The results showed that developed nitrate selective sensor could be successfully applied for continuous measurement of nitrate in microalgal productions at reduced cost.

Exopolysaccharides from microalgae: production, characterization, optimization and techno-economic assessment.

Microalgae cultivation for exopolysaccharide production has getting more attention as a result of their high hydrocarbon biosynthesis skill. The aim of this study is to examine the exopolysaccharide production potential of different species of microalgae. In this context, exopolysaccharides were produced from Chlorella minutissima, Chlorella sorokiniana and Botryococcus braunii microalgae and the effects of carbon and nitrogen content in the growth medium and illumination time on exopolysaccharide production were analyzed statistically using Box-Behnken experimental design. In addition, techno-economic assessment of exopolysaccharide production were also performed by using the most productive microalgae and optimum conditions determined in this study. As a result of the experiments, it was seen that C. minutissima, C. sorokiniana and B. braunii produced 0.245 ± 0.0025 g/L, 0.163 ± 0.0016 g/L and 0.117 ± 0.0007 g/L exopolysaccharide, respectively. Statistically, it was observed that there was an inverse relationship between the exopolysaccharide production and investigated parameters such as illumination period and carbon and nitrogen amounts of culture mediums. The techno-economic assessment comprising microalgal exopolysaccharide (EPS) bioprocess was carried out, and it showed that the system can be considered economically viable, yet can be improved with biorefinery approach.

Comparison of the anticancer effect of microalgal oils and microalgal oil-loaded electrosprayed nanoparticles against PC-3, SHSY-5Y and AGS cell lines.

Many of the bioactive substances used in pharmaceutical industry are easily affected by temperature, light and oxygen, and are easily degraded during storage and processing, and exhibit poor adsorption properties during digestion, which limits their direct use. Microalgae are rich in oils which have antimicrobial properties and antioxidants that attract attention in both food and pharmaceutical sectors in recent years. Studies to encapsulate bioactive compound-rich microalgae oils with nanotechnological approaches to improve the physical and chemical stability are relatively new, and it is promising to apply these approaches for pharmaceutical purposes. In this study, cytotoxic effects of oil extracts of Botryococcus braunii and Microcystis aeruginosa and their oil-loaded nanoparticles on L929 cell line, PC-3 prostate cell line, SHSY-5Y neuroblastoma cell line and AGS gastric adenocarcinoma cell line were investigated. The obtained extracts were found to have no cytotoxic effect on L929 cells. However, they showed cytotoxic effect on cancer cells. As for the nanoparticles; a gradual release was determined and the stability of the nanoparticle structure was shown. In the light of obtained findings, it was considered that nanoparticles produced with oil extracts of microalgae which have bioactive substances, have potential to be evaluated especially in pharmaceutical and cosmetic fields.

Antimicrobial and bacteriostatic activity of surfactants against B. subtilis for microbial cleaner formulation.

Cleaning products containing live bacteria that form spores of Bacillus spp. as active substances are becoming increasingly common in probiotic cleaner formulation. The quality of cleaning performance for the production of probiotic cleaners does not only depend on the potential of the bacterial strains used, but also on the chemical components of the formulations. In this study, the surfactants and other additives were investigated as biocidal or bacteriostatic against B. subtilis, and the viability of B. subtilis was examined at different pH ranges for microbial cleaner formulation. As a result, it was discovered that the B. subtilis, which can be used in the microbial cleaner formulation, shows higher growth and viability at the neutral pH, and it passes into the death phase at pH 3. According to antagonistic activity results, the Gram-positive S. aureus and K. pneumoniae were the most sensitive bacteria while B. cereus was the most resistant bacteria. The anionic surfactants such as linear alkylbenzene sulfonic acid and sodium lauryl ether sulfate act as bacteriostatic on Bacillus spp. and do not cause cell death. In the view of these results, the usage of appropriate bacterial cultures and the correct stabilization of the formulations are also critical elements in the development of microbial cleaner formulations.

Microalgal Bioprocess Toward the Production of Microalgal Oil Loaded Bovine Serum Albumin Nanoparticles.

Microalgal biotechnology has increased rapidly owing to have high value bioactive compounds and numerous consumer products that can be utilized from microalgae. With the development of novel cultivation and processing methods, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. In this context, especially for food and pharmaceutical applications, encapsulation of microalgal bioactive compounds is carried out to protect the compound from oxidation and degradation. In this study, a microalgal production process was carried out and microalgal oil loaded bovine serum albumin (BSA) nanoparticle production using glucose as cross-linking agent was investigated. The influences of different process parameters such as initial BSA concentration, glucose concentration and desolvation temperature on the size of BSA nanoparticles were investigated to achieve very small size nanoparticles. Furthermore, data obtained from the experiments were assessed statistically to model the process. It was found that the obtained nanoparticles showed spherical shape with the mean particle size of around 200-300 nm with zeta potential of about - 23 mV. Also, stability test showed that, there was not any change in particle size for one month storage and nanoparticle structure enhance the protection of microalgae oil from oxidation. At last, antibacterial effect of nanoparticles was presented against E. coli ATCC 8739 and L. monocytogenes ATCC 13932. In here, we demonstrated a microalgal bioprocess which consists of microalgae production to obtain microalgal oil riched in bioactive and, encapsulation of microalgal oil to protect it from environmental conditions.

A novel approach to production of Chlorella protothecoides oil-loaded nanoparticles via electrospraying method: Modeling of critical parameters for particle sizing.

Bioactive compounds in algae have chain rings that protect the tissue from chemical damage and disease symptoms. In addition, algal bioactive agents have the ability to stimulate the immune system, protective and therapeutic effects against many diseases, including various types of cancers, coronary heart disease, premature aging, and arthritis. These bioactive compounds also have antioxidant, anticoagulant, antiviral, and anti-inflammatory properties. It is very important to encapsulate these algal compounds for preserving bioactive properties. Two of the most efficient methods used for encapsulation are electrospraying and microemulsion techniques. Although electrospraying is a novel technique to produce nanoparticles in recent years, microemulsion is more conventional method compared with electrospraying. In this study, Chlorella protothecoides oil was encapsulated by using sodium alginate and chitosan biopolymers, and the effects of production parameters of electrospraying and microemulsion methods on the particle size and loading efficiency were investigated. Statistical modeling of critical parameters for particle sizing in microemulsion method and electrospraying technique, which is a novel approach to obtain microalgal oil-loaded nanoparticles, was also presented. It was seen that electrospraying is suitable for obtaining smaller nanoparticles (123.9-610 nm), homogeneous distribution, and higher oil loading efficiency (60%-77%) compared with microemulsion method (756.9-1128.2 nm and 57%-73%).

Utilization of struvite recovered from high-strength ammonium-containing simulated wastewater as slow-release fertilizer and fire-retardant barrier.

Sustainable uses of the struvite (magnesium ammonium phosphate hexahydrate, MgNH4PO4·6H2O, MAP) recovered from the synthetic wastewater, as a high-quality slow-release fertilizer for the growth of nine medicinal plants and a fire-retardant barrier on the flammability of cotton fabric and wooden plate, were explored in this study. The previous experimental results demonstrated that under the optimal conditions, about 98.7% of [Formula: see text] (initial [Formula: see text] = 1000 mg/L) could be effectively and successfully recovered from simulated wastewater in the form of MAP precipitate. Rates of increase in total fresh weights, total dry weights, and fresh heights of plants grown in soil fertilized with the struvite were determined as 67%, 52%, and 12% for valerian; 121%, 75%, and 18% for cucumber; 421%, 260%, and 47% for dill; 314%, 318%, and 27% for coriander; 432%, 566%, and 30% for tomato; 285%, 683%, and 26% for parsley; 200%, 225%, and 9% for basil; 857%, 656%, and 92% for rocket; and 146%, 115%, and 28% for cress, respectively, compared to the control pots. The microstructure, elemental composition, surface area, thermal behaviour, and functional groups of the grown crystals were characterized using SEM, EDS, BET, TGA-DTG-DSC, and FTIR analyses, respectively. Flammability tests and thermal analyses concluded that the dried and crumbled/implanted form of struvite used as a fire-retardant barrier demonstrated a remarkable flame-resistant behaviour for both cotton fabric and wooden plate. Findings of this experimental study clearly corroborated the versatility of struvite as non-polluting and environmentally friendly clean product for the sustainable usage in different fields.

Investigation of the antifungal effects of algal extracts on apple-infecting fungi.

It is known that cell extracts of various algae have antifungal activity against microorganisms in vitro. Antifungal activities of Ulva lactuca, Chlorella vulgaris, Chlorella minutissima, and Chlorella protothecoides were investigated against: Aspergillus niger, Alternaria alternata, and Penicillium expansum fungi to present their fungicide potentials. Aspergillus niger, Alternaria sp., and Penicillium expansum are typical soft-rotting fungi and cause important loss of apple fruit in the storage. In vitro antifungal activity was evaluated by agar disc diffusion assay against pathogenic apple rot fungi. As a result, almost all of the extracts obtained from algae species were revealed to have antifungal activity against selected fungal pathogens. Free radical-scavenging activity of the extracts was determined with 1,1-diphenyl-2 picryl hydrazyl (DPPH) free radical-scavenging method. Extract of C. protothecoides was determined to have a stronger antioxidant activity than other algae extracts. This study reveals that the potential of algae should be investigated for the production of natural fungicide for pharmaceutical and food industries.

In vitro cytotoxic activity of microalgal extracts loaded nano-micro particles produced via electrospraying and microemulsion methods.

Reactive oxygen species can bind protein, DNA, lipids, and carbohydrates and thus cause an oxidation reaction that induces various syndromes such as cardiovascular diseases, degenerative disease, and cancer types in the human body. Bioactive compounds, such as PUFA, EPA, DHA, and carotenoids in algae, have a chain ring and protect the tissue from chemical damage and reverse the symptoms of some diseases. Algal bioactives also have various biological properties such as anticoagulants, antiviral, antiangiogenic, antitumor, anti-inflammatory, antioxidant, antiproliferative, and immune modulation properties. This study aimed to show in vitro cytotoxic activity effect of Chlorella protothecoides and Nannochloropsis oculata microalgal extracts loaded nano-microparticles on A-172 (Homo sapiens brain glioblastoma) and HCT-116 (H. sapiens colon colorectal carcinoma) cell lines because of the increasing importance of algal biotechnology. MTT viability tests were performed on HUVEC, A172, and HCT 116 cells with particles obtained at optimum process parameters. The cell viability rates of encapsulated particles were also compared with pure algae extracts. Microalgal extracts loaded nano-micro particles showed very promising results for cytotoxic effect on cancer cells.

Optimization of pH induced flocculation of marine and freshwater microalgae via central composite design.

Microalgae harvesting via pH induced flocculation along with utilization of recovered medium after flocculation is one of the most economical methods for separating the microalgal biomass in order to reduce the dewatering cost. In this study, optimization of marine and freshwater microalgae flocculation by pH adjustment was investigated via central composite design methodology. One molar of KOH and NaOH solutions were used to increase the pH level of the microalgal culture. Increasing pH value of the medium provided the highest flocculation efficiency up to 92.63 and 86.18% with pH adjusted to 10.5 with KOH and NaOH solutions for marine microalgae Nannochloropsis oculata and freshwater microalgae Chlorella minutissima, respectively. Also, it was revealed that microalgae cells were still alive after flocculation process and their biochemical composition was not changed, and flocculated medium can be used again for the next microalgal production. According to the results, it can be said that this method is cheap and effective, simple to operate and provides the utilization of flocculated medium again.

Investigation of the biogas production potential from algal wastes.

In recent years, researchers focused their attention on biogas production more than ever to meet the energy demand. Especially, biogas obtained from algal wastes has become a trending research area owing to the high content of volatile solids in algae. The main purpose of this study is to determine the biogas production potential from algal wastes and examine the effect of temperature and particle size parameters on biogas yield. A comparison was made between the biogas production potential of microalgal wastes, obtained after oil extraction, and macroalgal wastes collected from coastal areas. It was found that algal biogas yield is directly proportional to temperature and inversely proportional to particle size. Optimal conditions for biogas production from algal wastes were determined as the temperature of 55 °C, a particle size of 200 µm, a residence time of 30 days and an alga-inoculum ratio of 1:4 (w:w). Highest biogas yield obtained under these conditions was found as 342.59 cm3 CH4 g-1 VS with Ulva lactuca. Under thermophilic conditions, both micro- and macroalgal biogas yields were comparable. It can be concluded that algal biomass is a good source for biogas production, although further research is needed to increase biogas yield and quality.

Effect of Chemical Pre-treatments on Bioethanol Production from Chlorella minutissima.

In recent years, algal bioethanol production comes into prominence as a trend towards sustainable development. Due to being sustainable energy source and environmental friendly, bioethanol production from algae is becoming increasingly popular all over the world. However, yield of bioethanol production from algae is lower than first generation feedstock's currently, and needs to be improved. In order to increase bioethanol yield, pre-treatments should be performed as cell disruption process on algal biomass. For this reason, researchers investigate the most appropriate pre-treatment method and its parameters for high yield bioethanol production from algae. In this study, cultivated Chlorella minutissima was utilized for bioethanol production. Effects of pre-treatment method (dilute acid and alkaline), chemical concentration, pre-treatment temperature and pre-treatment time on bioethanol yield were investigated. It was found that, the highest bioethanol yield was obtained as 18.52% with acid pre-treatment at pre-treatment temperature of 100 °C and pre-treatment time of 60 minutes.

Biodiesel Production from Chlorella protothecoides Oil by Microwave-Assisted Transesterification.

In this study, biodiesel production from microalgal oil by microwave-assisted transesterification was carried out to investigate its efficiency. Transesterification reactions were performed by using Chlorella protothecoides oil as feedstock, methanol, and potassium hydroxide as the catalyst. Methanol:oil ratio, reaction time and catalyst:oil ratio were investigated as process parameters affected methyl ester yield. 9:1 methanol/oil molar ratio, 1.5% KOH catalyst/oil ratio and 10 min were optimum values for the highest fatty acid methyl ester yield.

Removal of copper from aqueous solutions by adsorption onto chestnut shell and grapeseed activated carbons.

Activated carbons prepared from chestnut shell and grapeseed were used as adsorbent for the removal of Cu (II) ions from aqueous solutions. Adsorption experiments were performed by varying initial metal ion concentration, temperature and pH. Freundlich and Langmuir isotherms were used to analyze the equilibrium data obtained at different adsorption conditions. It was observed that Freundlich isotherm provided better fit to the equilibrium data than Langmuir isotherm. Effects of temperature, pH and adsorbent surface area on the adsorption capacity constant of Freundlich and Langmuir isotherms were statistically investigated by using a two-level factorial design technique and empirical regression equations were developed. It was determined that the adsorption capacities of adsorbents increased with increasing temperature, pH and surface area. The SEM images of adsorbents before and after adsorption were compared.