Agitation Conditions Research Articles

Seaweed liquid extract AS novel sustainable solutions for phycobioremediation plant germination, and feed additive for marine invertebrate copepod

Several studies have shown the importance of using seaweed liquid extract (True-Algae-Max, TAM) as a fish feed additive, and fish-water conditioner. In addition, TAM has demonstrated significant growth improvement when used as a plant growth biostimulant. This study investigates whether seaweed liquid extract (TAM) can achieve good results in new experimental fields such as chromium remediation, plant germination, and live feed supplementation for marine invertebrate Copepod (Oithona nana). In this study, several doses of TAM were tested, for the first time, for their impact on the remediation of chromium (Cr6+) ions from aqueous solutions and as an aqua feed additive for marine copepods (Oithona nana). In addition, it has been tested as promising for the seed germination of Fenugreek (Trigonella foenum-graecum) and Faba bean (Vicia faba L.). The most important factors influencing the removal (%) of Cr6+, identified using a two-level Plackett–Burman factorial design, were selected for additional optimization utilizing a rotatable central composite design. The maximum adsorption of Cr6+ was 93.65% under ideal operating circumstances, which included an initial Cr6+ concentration of 60 mg L−1, a temperature of 25 °C, a pH of 3, a TAM biomass of 0.05 g, and a contact time of 60 min at agitation conditions. Plackett–Burman design data shows the significance of each factor and how well the model fits the Cr6+ removal. The results of the germination experiment revealed that the highest significant increase in seed germination was achieved using a TAM level of 0.30 mg mL−1 with V. faba (88%) and 0.03 mg mL−1 with T. foenum-graecum (96.6%). Additionally, compared to the control group, TAM at a level of 0.037 mg mL−1 showed high root length enhancement on V. faba (184%) and T. foenum-graecum (188%). The results of the copepod O. nana feeding additive experiment found that the group fed on starch supplemented with TAM at a level of 0.3 mL L−1, compared to the control group that fed starch only, showed the highest increment in population growth (134.74%), fecundity (270.16%), and population composition of males (133.45%), adults (120.37%), and nauplius (203.18%). Moreover, compared to the control group, the copepod that fed starch supplemented with TAM levels achieved the highest Omega-9 content. In conclusion, it is shown that TAM is a feasible, efficient, and sustainable solution for biodegradable adsorbent for the Cr6+ from aqueous solution, enhances plant seed germination and root length, and is a novel feed additive for marine copepod O. nana, especially in marine invertebrate hatcheries.

Engineering thermotolerant Kluyveromyces marxianus strains for resveratrol production by simultaneous saccharification and fermentation of whole slurry corn cob

The microbial biosynthesis of the antioxidant compound resveratrol offers an eco-friendly and sustainable alternative to chemical synthesis or plant extraction. Here, we showed that Kluyveromyces marxianus strains produce p-coumaric acid, a key precursor of resveratrol, with higher titres achieved under increased agitation conditions. Through further strain engineering, resveratrol production was achieved using glucose, xylose, and/or ethanol as substrates. Xylose emerged as the most favourable carbon source for resveratrol production, with ethanol supplementation during xylose culture resulting in increased resveratrol titres by limiting the accumulation of the by-product xylitol. At 37 ◦C, resveratrol production from corn cob hydrolysate and whole slurry substantially increased the yield of resveratrol per sugar, reaching titres of up to 69.26 mg/L. This work shows, for the first time, resveratrol production by K. marxianus and from corn cob whole slurry, establishing foundations for the development of an integrated sustainable process for resveratrol production from lignocellulosic materials.

Efficient biodecolorization of direct black 22 Azo Dye by Aspergillus tamarii Kita UCP1279 isolated from caatinga soil

The textile industry is a major consumer of water, generating large volumes of wastewater contaminated with harmful substances, particularly azo dyes, which contain aromatic rings, amines, and sulfonic groups that contribute to their environmental toxicity. The use of microbial agents for wastewater treatment offers a cost-effective and sustainable solution, minimizing sludge production. Fungi from the Caatinga biome have demonstrated potential for bioremediation, especially under extreme environmental conditions. This study explores the ability of Aspergillus tamarii Kita to decolorize the azo dye Direct Black 22 (DB22) under varying conditions, including the use of both active and inactive fungal biomass, in static and agitated systems (120 rpm), at a controlled temperature of 30°C. Dye concentrations of 50, 125, and 250 mg/L were evaluated over time intervals of 75, 180, and 180 minutes, respectively. The influence of dissolved oxygen concentration and redox potential on the decolorization process was also investigated to identify optimal treatment conditions. Decolorization efficiency was quantified via spectrophotometric analysis. Results revealed decolorization rates of 100%, 97%, and 63% for the respective dye concentrations, with active biomass in agitated conditions achieving the highest removal rates. The study further demonstrated that dissolved oxygen levels and redox potential are critical factors in enhancing dye decolorization. These findings underscore the bioremediation potential of Aspergillus tamarii Kita in treating textile dye effluents, offering a promising approach to sustainable industrial wastewater management.

Transforming Wastewater into Biofuel: Nutrient Removal and Biomass Generation with Chlorella vulgaris

This study investigates the potential of Chlorella vulgaris for nutrient removal and biomass production in synthetic wastewater. The experiments were conducted in 2 L photobioreactors under controlled aeration, agitation, and lighting conditions for 19 days. Despite a moderate growth rate (0.137 d⁻¹), C. vulgaris achieved efficient pollutant removal, with 97% of nitrate, 90% of nitrite, and 90.6% of COD eliminated. Additionally, the biomass was processed to extract fatty acids, yielding a 20% extraction rate, indicating its potential as a biofuel feedstock. These results demonstrate C. vulgaris’s dual function in wastewater remediation and biofuel production, presenting a sustainable and economically viable approach to addressing environmental challenges.

Efficacy of Indigenous Bacteria in the Biodegradation of Hydrocarbons Isolated from Agricultural Soils in Huamachuco, Peru.

Pollution from crude oil and its derivatives poses a serious threat to human health and ecosystems, with accidental spills causing substantial damage. Biodegradation, using microorganisms to break down these contaminants, presents a promising and cost-effective solution. Exploring and utilizing new bacterial strains from underexplored habitats could improve remediation efforts at contaminated sites. This study aimed to evaluate the hydrocarbon biodegradation capacity of bacteria isolated from agricultural soils in Huamachuco, Peru. Soil samples from Oca crops were collected and bacteria were isolated. Biodegradation assays were conducted using diesel as the sole carbon source in the Bushnell Haas Mineral medium. Molecular characterization of the 16S rRNA gene identified four strains. Diesel biodegradation assays at 1% concentration were performed under agitation conditions at 150 rpm and 30 °C, and monitored on day 10 by measuring cellular biomass (OD600), with hydrocarbons analyzed by gas chromatography. The results showed Pseudomonas protegens (PROM2) achieved the highest efficiency in removing total hydrocarbons (91.5 ± 0.7%). Additionally, Pseudomonas citri PROM3 and Acinetobacter guillouiae ClyRoM5 also demonstrated high capacity in removing several individual hydrocarbons. Indigenous bacteria from uncontaminated agricultural soils present a high potential for hydrocarbon bioremediation, offering an ecological and effective solution for soil decontamination.

Stability and performance of BTC-based MOFs for environmental applications

Two series of open metal site MOFs, HKUST-1 and MIL-100(Fe), have been successfully prepared using different methods of synthesis. Their features depend on the synthetic route as well as their role play in different environmental applications. The stability and performance of these BTC-based MOFs have been tested bearing in mind Congo Red (CR) removal, humidity adsorption and iodine capture and release. HKUST-1 and MIL-100(Fe) samples could offer a remarkable role in the adsorption of CR from aqueous solutions. However, the lability of HKUST-1 in water is revealed as a drawback for its reutilization in both static and agitation conditions. The former contrasts to the stability under ambient moisture. MIL-100(Fe) shows promising properties in both CR adsorption in aqueous solutions and humidity adsorption. Nonetheless, the performance largely depends on the synthesis conditions. Although CR removal is based on surface interaction, there is a relation between the adsorpted quantity and the specific surface area. The size and nature of iodine allows the diffusion in the pores of both HKUST-1 and MIL-100(Fe) MOFs. This way, the uptake of iodine is driving by the porosity and surface area of samples rather than their inherent nature. As a rule, the results of this work indicate that not only is it important the specific nature of the MOF chosen for a given application but also the way in which it has been synthesized and the conditions in which they are used. MIL-100(Fe)-R is revealed as the best suitable candidate to be used as a sorbent for CR in aqueous solutions, moisture and I2 gas.

Identification of Secondary Metabolites by UHPLC-ESI-HRMS/MS in Antifungal Strain Trichoderma harzianum (LBAT-53).

Trichoderma spp. are filamentous fungi generally observed in nature, which are widely marketed as biocontrol agents. The secondary metabolites produced have obtained special attention since they possess attractive chemical structures with a broad spectrum of biological activities. In Cuba, the species of Trichoderma have been commercially applied for the control of several phytopathogens to protect agricultural crops, but few studies have been carried out to detect and characterize the production of metabolites with biological activity. The strain Trichoderma harzianum LBAT-53 was subjected to an antifungal in vitro assay against Fusarium oxysporum f.sp. cubense by dual culture and volatile metabolite assays and fermented in PDB under constant agitation conditions. The ethyl acetate crude extract was obtained by liquid-liquid extraction. The fungal extract was investigated for the composition of secondary metabolites through chemical screening and ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in negative ionization mode. As a result, LBAT-53 showed antagonistic activity in vitro (Class 2) against the pathogen evaluated in direct confrontation (76.9% of inhibition in 10 days) and by volatile metabolites (<40% in 7 days). Furthermore, seven low-molecular-weight phenolic compounds, including chrysophanol, phomarin, endocrocin, and trichophenol A, among others, were identified using UHPLC-ESI-MS/MS. This study is the first work on the characterization of secondary metabolites produced by the commercially applied strain LBAT-53, which is a promising source of bioactive compounds. These results provide a better understanding of the metabolism of this fungus, which is widely used in Cuba as biopesticides in agriculture pest control.

Optimization of the enzymatic clarification process of glucose syrups derived from agro-industrial residues

In this work, the application of pectinase enzymes to clarify glucose syrups produced from corn fiber was studied. The enzymatic activity and kinetic parameters of the pectinase enzyme used were quantified. A specific activity of 5,528 U/mg protein, a maximum rate of 19151 U/mL, and a Michaelis-Menten constant of 1,656 mg/mL were obtained. The syrup was prepared by hydrolyzing corn fiber at 50°C and 180 rpm, and a central composite design was performed for the clarification step to find the optimal conditions of enzyme-substrate ratio and agitation. The syrup was heated to a temperature of 50°C, and an enzyme substrate ratio between 2.5 to 4.5 U/mL of syrup and agitation, varying between 215 to 285 rpm, was applied. The conditions to maximize the clarification of corn fiber syrup were determined to be an enzyme substrate ratio of 3.716 U/mL syrup and agitation of 267 rpm. These conditions were validated by taking the syrup from clarity of 65.8% to 88.1%, demonstrating that the methodology used presents advantages in the syrup clarification process. A physicochemical characterization of the corn fiber used to prepare the syrups was carried out, which presented a content of 12.90%, 23.33%, 13.4%, and 0.36% of cellulose, hemicellulose, lignin and pectin, respectively.

Intensification of Rindera graeca transgenic roots proliferation and deoxyshikonin secretion in wave-agitated disposable bioreactor

For millennia, plants have been a source of natural medicines used by humankind. In vitro cultures of plant organs, e.g., transgenic roots, provide a suitable environment for maintaining plant biomass and continuously producing plant-derived bioproducts. The in vitro cultures of plant biomass can be efficiently scaled up using disposable bioreactors with wave-type agitation conditions. The study aimed to investigate the influence of wave-type agitation conditions supported by the WAVE 25 bioreactor on biomass proliferation and secondary metabolite production offered by the in vitro system of Rindera graeca transgenic root culture. Two morphologically different pellets of R. graeca biomass have been observed: highly ramified for cultures performed at ReL < 4000 and compacted for cultures performed at ReL > 5200. The growth of transgenic root biomass cultured in the WAVE 25 bioreactor at ReL = 1325 was over two times higher than for cultures performed in small-scale systems of oscillatory shaken Erlenmeyer flasks.

A novel simultaneous short-course nitrification, denitrification and fermentation process: bio-enhanced phenol degradation and denitrification in a single reactor.

The feasibility of a simultaneous nitrification, denitrification and fermentation process (SNDF) under electric stirrer agitation conditions was verified in a single reactor. Enhanced activated sludge for phenol degradation and denitrification in pharmaceutical phenol-containing wastewater under low dissolved oxygen conditions, additional inoculation with Comamonas sp. BGH and optimisation of co-metabolites were investigated. At a hydraulic residence time (HRT) of 28h, 15mg/L of substrate as strain BGH co-metabolised substrate degraded 650 ± 50mg/L phenol almost completely and was accompanied by an incremental increase in the quantity of strain BGH. Strain BGH showed enhanced phenol degradation. Under trisodium citrate co-metabolism, strain BGH combined with activated sludge treated phenol wastewater and degraded NO2--N from 50 ± 5 to 0mg/L in only 7h. The removal efficiency of this group for phenol, chemical oxygen demand (COD) and TN was 99.67%, 90.25% and 98.71%, respectively, at an HRT of 32h. The bioaugmentation effect not only promotes the degradation of pollutants, but also increases the abundance of dominant bacteria in activated sludge. Illumina MiSeq sequencing research showed that strain BGH promoted the growth of dominant genera (Acidaminobacter, Raineyella, Pseudarcobacter) and increased their relative abundance in the activated sludge system. These genera are resistant to toxicity and organic matter degradation. This paper provides some reference for the activated sludge to degrade high phenol pharmaceutical wastewater under the action of biological enhancement.

The role of shear forces in primary and secondary nucleation of amyloid fibrils

Shear forces affect self-assembly processes ranging from crystallization to fiber formation. Here, the effect of mild agitation on amyloid fibril formation was explored for four peptides and investigated in detail for A[Formula: see text]42, which is associated with Alzheimer's disease. To gain mechanistic insights into the effect of mild agitation, nonseeded and seeded aggregation reactions were set up at various peptide concentrations with and without an inhibitor. First, an effect on fibril fragmentation was excluded by comparing the monomer-concentration dependence of aggregation kinetics under idle and agitated conditions. Second, using a secondary nucleation inhibitor, Brichos, the agitation effect on primary nucleation was decoupled from secondary nucleation. Third, an effect on secondary nucleation was established in the absence of inhibitor. Fourth, an effect on elongation was excluded by comparing the seeding potency of fibrils formed under idle or agitated conditions. We find that both primary and secondary nucleation steps are accelerated by gentle agitation. The increased shear forces facilitate both the detachment of newly formed aggregates from catalytic surfaces and the rate at which molecules are transported in the bulk solution to encounter nucleation sites on the fibril and other surfaces. Ultrastructural evidence obtained with cryogenic transmission electron microscopy and free-flow electrophoresis in microfluidics devices imply that agitation speeds up the detachment of nucleated species from the fibril surface. Our findings shed light on the aggregation mechanism and the role of detachment for efficient secondary nucleation. The results inform on how to modulate the relative importance of different microscopic steps in drug discovery and investigations.

Use of Hansensiaspora uvarum and managing growth conditions increase polysaccharides and antioxidants content in yeast autolysates for winemaking

Yeast derivatives are winemaking additives generally obtained from Saccharomyces spp., commonly used as fermentation and wine quality enhancers. Even though they are widely used, the production process - from initial biomass to their final composition, is not standardized and often not specific for winemaking purposes. In the present study, biomass production was performed by applying different temperatures and agitation conditions, to assess their effect on the chemical composition of the resulting derivatives, using S. cerevisiae and H. uvarum as starting microorganisms. The application of shaking mostly affected the chemical composition of yeast derivatives, resulting in the highest mean concentration of amino acids (146 mg/g in S. cerevisiae), polysaccharides (370 mg/g in H. uvarum), and glutathione (about 85 μmol/g in S. cerevisiae). Derivatives obtained from H. uvarum were characterized by a non-negligible amount of glutathione (35.6 μmol/g - 53.1 μmol/g) and cysteine (12.7 μmol/g - 26.2 μmol/g), regardless of the growth conditions previously applied; only for this strain, reducing proteins linked to cell wall residues were detected. The results obtained suggest that the chemical composition of yeast derivatives may be managed during biomass production, also using specific strains, thus possibly obtaining products naturally rich in compounds of enological interest.

Efficient cadmium removal from industrial wastewater generated from smelter using chemical precipitation and oxidation assistance.

The effective treatment of cadmium (Cd) in smelting wastewater is of great industrial importance. This study investigates the efficient removal of Cd from real industrial smelting wastewater via chemical precipitation using a series of experiments. In particular, the effects of different precipitants, agitation conditions, and the addition of NaOCl on Cd removal and pH variation are investigated. CaO (3.75 g/L), NaOH (3.50 g/L), and Ca(OH)2 (3.75 g/L) are found to be effective in elevating the wastewater pH and achieving high Cd removal rates (>99.9%), while the use of NaOH as a precipitant maintains a high Cd removal rate even at low agitation intensities. The properties of the produced sludge and supernatant are also determined using moisture content, particle size, and sludge leaching analyses due to the importance of economic and environmental sustainability in filtration, dewatering, and waste disposal processes. In addition, the addition of 2% NaOCl is tested, revealing that it can improve the Cd removal efficiency of Ca(OH)2, thus potentially reducing processing costs and enhancing the environmental benefits. Overall, these findings offer valuable insights into the removal of Cd from smelting wastewater, with potential implications for both environmental sustainability and economic viability. PRACTITIONER POINTS: CaO, NaOH, and Ca(OH)2 effectively remove Cd (>99.9%) from smelting wastewater. The use of NaOH leads to high Cd removal rates even at low agitation speeds. Adding 2% NaOCl can reduce the Ca(OH)2 dose for more economical Cd removal.

Effect of addition of γ-poly glutamic acid on bacterial nanocellulose production under agitated culture conditions.

Bacterial nanocellulose (BNC), a natural polymer material, gained significant popularity among researchers and industry. It has great potential in areas, such as textile manufacturing, fiber-based paper, and packaging products, food industry, biomedical materials, and advanced functional bionanocomposites. The main current fermentation methods for BNC involved static culture, as the agitated culture methods had lower raw material conversion rates and resulted in non-uniform product formation. Currently, studies have shown that the production of BNC can be enhanced by incorporating specific additives into the culture medium. These additives included organic acids or polysaccharides. γ-Polyglutamic acid (γ-PGA), known for its high polymerization, excellent biodegradability, and environmental friendliness, has found extensive application in various industries including daily chemicals, medicine, food, and agriculture. In this particular study, 0.15g/L of γ-PGA was incorporated as a medium additive to cultivate BNC under agitated culture conditions of 120rpm and 30℃. The BNC production increased remarkably by 209% in the medium with 0.15g/L γ-PGA and initial pH of 5.0 compared to that in the standard medium, and BNC production increased by 7.3% in the medium with 0.06g/L γ-PGA. The addition of γ-PGA as a medium additive resulted in significant improvements in BNC production. Similarly, at initial pH levels of 4.0 and 6.0, the BNC production also increased by 39.3% and 102.3%, respectively. To assess the characteristics of the BNC products, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used. The average diameter of BNC fibers, which was prepared from the medium adding 0.15g/L γ-PGA, was twice thicker than that of BNC fibers prepared from the control culture medium. That might be because that polyglutamic acid relieved the BNC synthesis from the shear stress from the agitation. This experiment held great significance as it explored the use of a novel medium additive, γ-PGA, to improve the production and the glucose conversion rate in BNC fermentation. And the BNC fibers became thicker, with better thermal stability, higher crystallinity, and higher degree of polymerization (DPv). These findings lay a solid foundation for future large-scale fermentation production of BNC using bioreactors.

Optimized submerged batch fermentation for metabolic switching in Streptomyces yanglinensis 3-10 providing platform for reveromycin A and B biosynthesis, engineering, and production.

The cultivation system requires that the approach providing biomass for all types of metabolic analysis is of excellent quality and reliability. This study was conducted to enhance the efficiency and yield of antifungal substance (AFS) production in Streptomyces yanglinensis 3-10 by optimizing operation conditions of aeration, agitation, carbon source, and incubation time in a fermenter. Dissolved oxygen (DO) and pH were found to play significant roles in AFS production. The optimum pH for the production of AFS in S. yanglinensis 3-10 was found to be 6.5. As the AFS synthesis is generally thought to be an aerobic process, DO plays a significant role. The synthesis of bioactive compounds can vary depending on how DO affects growth rate. This study validates that the high growth rate and antifungal activity required a minimum DO concentration of approximately 20% saturation. The DO supply in a fermenter can be raised once agitation and aeration have been adjusted. Consequently, DO can stimulate the development of bacteria and enzyme production. A large shearing effect could result from the extreme agitation, harming the cell and deactivating its products. The highest inhibition zone diameter (IZD) was obtained with 3% starch, making starch a more efficient carbon source than glucose. Temperature is another important factor affecting AFS production. The needed fermentation time would increase and AFS production would be reduced by the too-low operating temperature. Furthermore, large-scale fermenters are challenging to manage at temperatures that are far below from room temperature. According to this research, 28°C is the ideal temperature for the fermentation of S. yanglinensis 3-10. The current study deals with the optimization of submerged batch fermentation involving the modification of operation conditions to effectively enhance the efficiency and yield of AFS production in S. yanglinensis 3-10.

Coconut fibre for the synthesis of microfibrillated cellulose: Thermal analysis experimental characterization

AbstractFibrillated cellulose at nano‐ and microscales was obtained from green coconut fibre. The biomass was subjected to mechanical treatment (comminution and sieving of the fibres) and chemical treatment (washed with water, treated with sodium hydroxide, bleached with sodium chlorite, and subjected to acid hydrolysis). Finally, purification steps included centrifugation, dialysis, and ultrasound. The product obtained by acid hydrolysis, the crude fibre, and the intermediate‐treated samples were examined by scanning electron microscopy (SEM) and characterized by chemical analysis and thermogravimetry (TGA/DTG). The chemical characterization for crude coconut fibre demonstrated 27.99% ± 1.98% for cellulose, 14.11% ± 4.44% for hemicellulose, 25.15% ± 0.04% for lignin, and 19.34% ± 0.02% for ashes. The applied pretreatment used to remove hemicellulose and lignin from the crude coconut fibre permitted obtaining high levels of cellulose, such as 94.94% ± 5.46% for the hardest condition, with NaOH 11% (w/v)/NaClO2. Then, acid hydrolysis was used to obtain the micro‐scale cellulose structures with 50% H2SO4 at 45°C for 90 min in an agitated condition (100 rpm). Following pretreatment with 2% and 11% NaOH/NaClO2, respectively, microfibrillated cellulose was verified at levels of 0.9% and 0.75% by thermogravimetric analysis, while the commercial sample had a verification level of 1.89%. The produced micro cellulose was fibrillated with a diameter equal to 149.39 ± 40.63 nm and a length of 1764.07 ± 1109.18 nm, as determined by SEM.

Method for predicting the size of Ni1/3Mn1/3Co1/3(OH)2 particles precipitated in a stirred-tank semi-batch crystallizer using CFD and particle agglomeration models

NixMnyCoz(OH)2 is widely used as a precursor for the cathode active material LiNixMnyCozO2 in lithium ion batteries, and the precursor size, which determines the size of the active cathode material, affects the characteristics of lithium-ion batteries. This paper proposes a method for predicting the particle size of Ni1/3Mn1/3Co1/3(OH)2 precipitated by semi-batch reaction crystallization. The distribution of supersaturated components formed in the reactor varies with the reactor scale, feed conditions of the raw material solution, and agitation conditions. Therefore, the method presented in this paper considers the effects of these conditions on particle growth. First, to identify the turbulent dispersion and concentration distribution of the supersaturated components formed in the reaction crystallizer, a computational fluid dynamics (CFD) model was constructed consisting of the governing equations of hydrodynamics and the mass balance equations of the supersaturated components considering the production by neutralization and consumption by precipitation. Next, a model of agglomeration was constructed that focused on the balance of the binding and breaking up energies for the particle pairs. The binding energy was quantified based on the bridging between particle pairs by surface deposition. The breaking up-energy was quantified based on the hydrodynamic forces when the agglomerate passes through the impeller. These models were fitted using experimental results for the final average size of the Ni1/3Mn1/3Co1/3(OH)2 secondary aggregate, which was precipitated in a small-scale stirred-tank type semi-batch reaction crystallizer. The models predicted the experimental results of the final average size in a large-scale crystallizer, with the feeding conditions of the raw material solution and stirring conditions as experimental parameters, within ±20%. The models may be used to analyze semi-batch reaction crystallization systems of NixMnyCoz(OH)2 of any composition by adjusting the model parameters according to the procedure developed in this study.

Isolation and identification of Actinomycetes with antifungal activity from karts ecosystem in Maros-Pangkep, Indonesia

Abstract. Rante H, Manggau MA, Alam G, Pakki E, Erviani AE, Hafidah N, Abidin HL, Ali A. 2024. Isolation and identification of Actinomycetes with antifungal activity from karts ecosystem in Maros-Pangkep, Indonesia. Biodiversitas 25: 458-464. Actinomycetes have yielded various biologically active secondary compounds with intriguing properties like antimicrobial, antiviral, and anticancer effects. This research aimed to isolate, identify, and screen the antifungi from soil environmental samples collected from the karst ecosystem in Maros-Pangkep, Indonesia. The active isolate is then fermented for the production of secondary metabolites. The fermentation process uses an M1 medium under agitated conditions at 150 rpm for 12 days. The isolate Actinomycetes were identified based on sequence gen 16S rRNA. Screening of antifungal activity was carried out against Candida albicans ATCC 10231 and Aspergillus niger ATCC 16404 by antagonistic test. The diffusion method was applied using the paper disc to assess the antifungal activity. The result revealed that 8 isolates were purified from the soil samples collected. From the 8 isolates of Actinomycetes obtained, two Actinomycetes exhibited antifungal activities in the screening methods, namely isolates with code B11 and B 17. The crude extract of isolate B11 was active against C. albicans and A. niger at concentrations of 2 mg/paper disc, 1.5 mg/paper disc, and 0.75 mg/paper disc. Furthermore, isolate B17 was found to be only active against C. albicans. The phylogenetic analysis of the 16S rRNA gene sequences indicated that B11 showed the highest similarity to Streptomyces tuirus strain NBRC 15617.

Impact of agitation and non-agitation on microbiota and reactor performance in anaerobic digestion

Optimizing process conditions in anaerobic digestion could enhance the utilization of organic matter for renewable energy generation. Thus, initial upset substrates with elevated volatile fatty acids were investigated under agitation and non-agitation conditions for optimal bioreactor performance. There were two continuous agitation scenarios for the liquid-state (40 and 100 rpm) with a non-agitated scenario. Similarly, a non-agitated and 40 rpm scenario for the solid-state. The result indicated that the non-agitated liquid-state reactor had the highest methane yield (193 L/kgVS) and lowest retention (51 days) despite delayed microbial adaptation. Of the prominent microbes, the relative abundance of Firmicutes and Archaea_unclassified negatively correlated with VFA at 100 rpm. Contrarily at 40 rpm, Firmicutes correlated positively with VFA, an indication that Firmicutes could withstand acid production at agitation speed ≤40 rpm suggesting that agitation associated with VFA might reduce microbial diversity in an initial upset liquid-state bioreactor. Thus, upset influent could be utilized for energy generation with a non-agitated liquid-state bioreactor.

Growth Performance of a Newly Isolated and Culturable Thraustochytrid Strain from Sea Squirt Colonies

The world’s oceans and seas host &gt;100 known strains of thraustochytrids, a common group of marine eukaryotic unicellular protists, residing in diverse marine habitats, with many others to be isolated and cultivated. The thraustochytrids have become of considerable industrial interest due to health benefits gained from their high percentages of valuable bioactive compounds, revealing the needs for the isolation of new potential strains. Employing a recently developed isolation methodology (use of cell culture medium), we assess initial culture conditions and growth paces of newly isolated thraustochytrid cells (thraustochytrid sp. BSH), originated from the colonial tunicate Botryllus schlosseri, residing on Helgoland Island, Germany. Cells were cultivated under static versus agitated conditions, along with two inoculation sizes (0.5 × 106 and 1 × 106 cells/dish) and in three vessel types (35 mm Petri dishes and T25 and T75 flasks; containing 3, 5 and 15 mL medium, respectively). Cultures were observed under regular microscopy, confocal microscopy and H&amp;E staining. While cells in all conditions grew fast, results revealed the superiority of agitated cultivation in T75 flasks inoculated with 0.5 × 106 cells/dish (6.41 ± 1.91-fold increase/week). Further, 18S rDNA revealed high similarities (99.5–99.8) of strain BSH to two thraustochytrid strains from Monterey, California (USA), B. schlosseri colonies, elucidating a new understanding of these animals-protists associations.