Herein, we systematically reported the capability of T. harzianum RY44 for decolorization of Mordant orange-1. The fungi strains were isolated from the Universiti Teknologi Malaysia tropical rain forest. For initial screening, the decolorization was conducted using 50 strains of the fungi for 20 days incubation time and the best performance was selected. Then, the decolorization capability and fungal biomass were evaluated using different dye concentrations, namely, 0, 50, 75 and 100 ppm. Effects of the carbon sources (fructose, glucose, and galactose), nitrogen sources (ammonium nitrate, ammonium sulfate and yeast extract), surfactant (tween 80), aromatic compounds (benzoic acid, catechol and salicylic acid), and pH on the decolorization efficiency were examined. This study has found that the employed carbon sources, nitrogen sources, and aromatic compounds strongly enhance the decolorization efficiency. In addition, increasing the surfactant volume and pH generally decreased the decolorization efficiencies from 19.5 to 9.0% and 81.7 to 60.5%, respectively. In the mechanism philosophy, the present work has found that Mordant orange-1 were initially degraded by T. harzianum RY44 to benzoic acid and finally transformed into salicylic acid.
In this study, phyto-synthesis of silver nanoparticles (AgNPs) was achieved using an aqueous leaf extract of Alternanthera tenella. The phytochemical screening results revealed that flavonoids are responsible for the AgNPs formation. The AgNPs were characterised using UV-visible spectrophotometer, field emission scanning microscopy/energy dispersive X-ray, transmission electron microscopy, fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction. The average size of the nanoparticles was found to be ≈48 nm. The EDX results show that strong signals were observed for the silver atoms. The strong band appearing at 1601-1595 cm(-1) correspond to C-C stretching vibration from dienes in FT-IR spectrum indicating the formation of AgNPs. Human breast adenocarcinoma (MCF-7) cells treated with various concentrations of AgNPs showed a dose-dependent increase in cell inhibition. The IC50 value of the AgNPs was calculated to be 42.5 μg mL(-1). The AgNPs showed a significant reduction in the migration of MCF-7 cells.
Polyporus sp. S133 decolorized the Amaranth in 72 h (30 mg L(-1)) under static and shaking conditions. Liquid medium containing glucose has shown the highest decolorization of Amaranth by Polyporus sp. S133. When the effect of increasing inoculum concentration on decolorization of Amaranth was studied, maximum decolorization was observed with 15 % inoculum concentration. Significant increase in the enzyme production of laccase (102.2 U L(-1)) was observed over the period of Amaranth decolorization compared to lignin peroxidase and manganese peroxidase. Germination rate of Sorghum vulgare and Triticum aestivum was less with Amaranth treatment as compared to metabolites obtained after its decolorization. Based on the metabolites detected by GC-MS, it was proposed that Amaranth was bio-transformed into two intermediates, 1-hydroxy-2-naphthoic acid and 1,4-naphthaquinone. Overall findings suggested the ability of Polyporus sp. S133 for the decolorization of azo dye and ensured the ecofriendly degradation of Amaranth.
Recently, the increased demand of fructooligosaccharides (FOS) as a functional food has alarmed researchers to screen and identify new strains capable of producing fructosyltransferase (FTase). FTase is the enzyme that converts the substrate (sucrose) to glucose and fructose. The characterization of complex sugar such as table sugar, brown sugar, molasses, etc. will be carried out and the sugar that contained the highest sucrose concentration will be selected as a substrate. Eight species of macro-fungi will be screened for its ability to produce FTase and only one strain with the highest FTase activity will be selected for further studies. In this work, neural networks (NN) have been chosen to model the process based on their excellent 'resume' in coping with nonlinear process. Bootstrap re-sampling method has been utilized in re-sampling the data in this work. This method has successfully modeled the process as shown in the results.
A conventional reactor in microbial electrochemical technology (MET) consists of anode and cathode compartments divided by a separator, which is usually a proton exchange membrane (PEM), such as Nafion 117. In this study, a novel porous clay earthenware (NCE) was fabricated as the separator to replace the highly cost PEM. The fabrication of NCEs is with raw clay powder and starch powder that acts as a pore-forming agent at different starch powder contents (10 vol%, 20 vol%, and 30 vol%), ball-milled before hydraulically pressed to form green ceramic pellets and sintered up to 1200 °C. The highest power density of 2250 ± 21 mW/m2 (6.0 A/m2), the internal resistance of 75 ± 24 Ω and coulombic efficiency (CE) of 44 ± 21% were produced for MFC-NCE from 30 vol% starch powder content under batch mode operation. The MFC-PEM combination produced the lowest power density, CE and the highest internal resistance up to 1350 ± 17 mW/m2 (3.0 A/m2), 23 ± 15% and 326 ± 13 Ω, respectively.
This paper demonstrates Pseudomonas cepacia lipase catalyzed hydrolysis of p-nitrophenyl palmitate under irradiation of light with wavelengths of 250-750 nm. The reaction follows Michaelis-Menten Kinetics and the light irradiation increases the overall rate of hydrolysis. Using Lineweaver-Burk plot K M and V max values for the reaction in presence of light are found to be 39.07 and 66.67 mM/min/g, respectively; while for the same reaction under dark condition, the values are 7.08 and 10.21 mM/min/g. The linear form of enzyme dependent rate of reaction confirms that no mass-transfer limitations are present and the reaction is a kinetically controlled enzymatic reaction.
Immobilized Candida rugosa lipase was used for the synthesis of citronellyl laurate from citronellol and lauric acid. Screening of different types of support (Amberlite MB-1 and Celite) for immobilization of lipase and solvent (n-hexane, n-heptane, and iso-octane) and optimization of reaction conditions, such as catalyst loading, effect of substrates molar ratio and temperature, have been studied. The maximum enzyme activity was obtained at 310 K. The immobilized C. rugosa lipase onto Amberlite MB-1 support was found to be the best support with a conversion of 89% of citronellyl laurate ester in iso-octane compared to Celite 545. Deactivation of C. rugosa lipase at 313, 318 and 323 K were observed. Ordered bi bi mechanism with dead end complex of lauric acid was found to fit the initial rate data and the kinetic parameters were obtained by non-linear regression analysis.
The ability of immobilized cell cultures of Aspergillus niger FETL FT3 to produce extracellular tannase was investigated. The production of enzyme was increased by entrapping the fungus in scouring mesh cubes compared to free cells. Using optimized parameters of six scouring mesh cubes and inoculum size of 1 × 10(6) spores/mL, the tannase production of 3.98 U/mL was obtained from the immobilized cells compared to free cells (2.81 U/mL). It was about 41.64% increment. The immobilized cultures exhibited significant tannase production stability of two repeated runs.
Acidophiles are a group of microorganisms that thrive in acidic environments where pH level is far below the neutral value 7.0. They belong to a larger family called extremophiles, which is a group that thrives in various extreme environmental conditions which are normally inhospitable to other organisms. Several human activities such as mining, construction and other industrial processes release highly acidic effluents and wastes into the environment. Those acidic wastes and wastewaters contain different types of pollutants such as heavy metals, radioactive, and organic, whose have adverse effects on human being as well as on other living organisms. To protect the whole ecosystem, those pollutants containing effluents or wastes must be clean properly before releasing into environment. Physicochemical cleanup processes under extremely acidic conditions are not always successful due to high cost and release of toxic byproducts. While in case of biological methods, except acidophiles, no other microorganisms cannot survive in highly acidic conditions. Therefore, acidophiles can be a good choice for remediation of different types of contaminants present in acidic conditions. In this review article, various roles of acidophilic microorganisms responsible for removing heavy metals and radioactive pollutants from acidic environments were discussed. Bioremediation of various acidic organic pollutants by using acidophiles was also studied. Overall, this review could be helpful to extend our knowledge as well as to do further relevant novel studies in the field of acidic pollutants remediation by applying acidophilic microorganisms.
The effects of structure and concentration of surfactants on the biodegradation of fluoranthene, a three rings polycyclic aromatic hydrocarbon in the aqueous phase, as well as their effects on the biodegradation and enzyme activity were investigated. The toxicity ranking of studied surfactants is: non-ionic Tween 80 4,500 mg/L) was showed by Tween 80 (10 mg/L) culture, manifesting that the non-ionic surfactant present in the culture were beneficial to the fungal growth. Laccase showed the highest enzymes activity in all surfactants culture. Non-ionic Tween 80 showed a significant result for laccase activity (1,902 U/L) in the Armillaria sp. F022 culture. The increased enzymes cumulative activity may stem directly from the rising fluoranthene biodegradability as addition of appropriate surfactants. The biotransformation of fluoranthene was greatly improved by Tween 80, and totally fluoranthene degradation was obtained as Tween 80 was 10 mg/L. Two fluoranthene metabolites were isolated from the culture medium and analyzed by a thin layer chromatography, UV visible spectrometer and gas chromatography-mass spectrometry (GC-MS). The oxidation of fluoranthene is initiated by oxygenation at the C-2,3 positions resulting 9-fluorenone. At the end of experiment, one metabolite was detected in the culture extract and identified as phthalic acid. Evidently, Armillaria sp. F022 seems efficient, high effective and deserves further application on the enhanced bioremediation technologies for the treatment of fluoranthene-contaminated soil.
Armillaria sp. F022 is a white-rot fungus isolated from a tropical rain forest in Indonesia that is capable of utilizing pyrene as a source of carbon and energy. Enzymes production during the degradation process by Armillaria sp. F022 was certainly related to the increase in biomass. In the first week after incubation, the growth rate rapidly increased, but enzyme production decreased. After 7 days of incubation, rapid growth was observed, whereas, the enzymes were produced only after a good amount of biomass was generated. About 63 % of pyrene underwent biodegradation when incubated with this fungus in a liquid medium on a rotary shaker (120 rpm, 25 °C) for 30 days; during this period, pyrene was transformed to five stable metabolic products. These metabolites were extracted in ethyl acetate, isolated by column chromatography, and then identified using thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). 1-Hydroxypyrene was directly identified by GC-MS, while 4-phenanthroic acid, 1-hydroxy-2-naphthoic acid, phthalic acid, and protocatechuic acid were identified to be present in their derivatized forms (methylated forms and silylated forms). Protocatechuic acid was the end product of pyrene degradation by Armillaria sp. F022. Dynamic profiles of two key enzymes, namely laccase and 1,2-dioxygenase, were revealed during the degradation process, and the results indicated the presence of a complicated mechanism in the regulation of pyrene-degrading enzymes. In conclusion, Armillaria sp. F022 is a white-rot fungus with potential for application in the degradation of polycyclic aromatic hydrocarbons such as pyrene in the environment.
Oil palm fronds are the most abundant lignocellulosic biomass in Malaysia. In this study, fronds were tested as the potential renewable biomass for ethanol production. The soaking in aqueous ammonia pretreatment was applied, and the fermentability of pretreated fronds was evaluated using simultaneous saccharification and fermentation. The optimal pretreatment conditions were 7 % (w/w) ammonia, 80 °C, 20 h of pretreatment, and 1:12 S/L ratio, where the enzymatic digestibility was 41.4 % with cellulase of 60 FPU/g-glucan. When increasing the cellulase loading in the hydrolysis of pretreated fronds, the enzymatic digestibility increased until the enzyme loading reached 60 FPU/g-glucan. With 3 % glucan loading in the SSF of pretreated fronds, the ethanol concentration and yield based on the theoretical maximum after 12 and 48 h of the SSF were 7.5 and 9.7 g/L and 43.8 and 56.8 %, respectively. The ethanol productivities found at 12 and 24 h from pretreated fronds were 0.62 and 0.36 g/L/h, respectively.
Anaerobic co-digestion (co-AD) of agro-industrial waste, namely, palm oil mill effluent (POME) and sugarcane vinasse (Vn), with water hyacinth (WH) as co-substrate was carried out in two separate Anaerobic Suspended Growth Closed Bioreactors (ASGCBs) under thermophilic (55 °C) conditions. The highest chemical oxygen demand (COD) and soluble COD reduction in co-AD of POME-WH (78.61%, 78.86%) is slightly higher than co-AD of Vn-WH (75.75%, 78.24%). However, VFA reduction in co-AD of POME-WH (96.41%) is higher compared to co-AD of Vn-WH (85.94%). Subsequently, biogas production peaked at 13438 mL/day values and 16122 mL/day for co-AD of POME-WH and Vn-WH, respectively. However, the methane content was higher in the co-AD of POME-WH (72.04%) than in the co-AD of Vn-WH (69.86%). Growth yield (YG), maximum specific substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) are higher in co-AD of POME-WH, as supported by the higher mixed liquor volatile suspended solids (MLVSS) and COD reduction efficiency compared to co-AD of Vn-WH. However, methane yield ([Formula: see text]) reported in the co-AD of POME-WH and Vn-WH are 0.2748 and 0.3112 L CH4/g CODreduction, respectively, which suggests that WH is a more suitable co-substrate for Vn compared to POME.
Conventionally, microalgal lipid extraction uses volatile organic compounds as an extraction solvent. However, these solvents are harmful to human and environmental health. Therefore, this study evaluated the feasibility of alternative green solvents, namely, ethanol, dimethyl carbonate (DMC), cyclopentyl methyl ether (CPME), and 2-methyltetrahydrofuran (2-MeTHF) in lipid extraction from Chlorella sp. via ultrasound-assisted extraction (UAE). This study indicated that extraction parameters, such as ethanol-to-2-MeTHF ratio, solvent-to-biomass ratio, temperature, and time, significantly affected the crude lipid yield (P
Organic solid waste composting is a complex process that involves many coupled physical, chemical and biological mechanisms. To understand this complexity and to ease in planning, design and management of the composting plant, mathematical model for simulation is usually applied. The aim of this paper is to develop a mathematical model of organic substrate degradation and its performance evaluation in solid waste windrow composting system. The present model is a biomass-dependent model, considering biological growth processes under the limitation of moisture, oxygen and substrate contents, and temperature. The main output of this model is substrate content which was divided into two categories: slowly and rapidly degradable substrates. To validate the model, it was applied to a laboratory scale windrow composting of a mixture of wood chips and dog food. The wastes were filled into a cylindrical reactor of 6 cm diameter and 1 m height. The simulation program was run for 3 weeks with 1 s stepwise. The simulated results were in reasonably good agreement with the experimental results. The MC and temperature of model simulation were found to be matched with those of experiment, but limited for rapidly degradable substrates. Under anaerobic zone, the degradation of rapidly degradable substrate needs to be incorporated into the model to achieve full simulation of a long period static pile composting. This model is a useful tool to estimate the changes of substrate content during composting period, and acts as a basic model for further development of a sophisticated model.
Polycyclic aromatic hydrocarbon is a toxic recalcitrant environmental pollutant and its removal from the environment is very essential. In this study, a novel S1 strain isolated from the tropical rain forest was identified as Candida species based on 18S rRNA. The pyrene biodegradation was performed by Candida sp. S1. Pyrene was 35% degraded in 15 days. The percentage of pyrene biodegradation increased up to 75% with 24 g L-1of sodium chloride and decreased along with increasing salinity. Under the acidic condition, the biodegradation was increased up to 60% at pH 5. It was also found that the increasing glucose concentration of more than 10 g L-1had no significant effect on pyrene biodegradation, while agitation proved to have greater influence. There was a positive relationship between biomass growth and biodegradation rate of pyrene. One pyrene metabolite was identified from the extract solution and analyzed by a thin-layer chromatography, UV-visible absorption and gas chromatography-mass spectrometry. The metabolite found in the pyrene degradation was benzoic acid. Suitable conditions must be found to promote a successful microbial augmentation in liquid culture.
An effective biosurfactant producer and extremophiles bacteria, Bacillus cereus KH1, was isolated from textile effluent and the biosurfactant was produced using molasses as the sole carbon source. Growth parameters such as pH, temperature, salinity and concentration of molasses were optimised for decolourising the textile effluent with 24-h incubation. The biosurfactant property of B. cereus KH1 was evaluated based on haemolytic activity, oil displacement technique, drop-collapsing test and emulsification index. The results of the produced biosurfactant showed a positive reaction in haemolytic activity, oil displacement technique, drop-collapsing test and exhibiting a 67% emulsification index. The cell-free broth was stable in 40 °C pH 7, 7% salinity and 7% molasses. Thin-Layer Chromatography and Fourier Transform Infrared Spectroscopy analysis revealed that the biosurfactant was a lipopeptide with a yield 2.98 g L-1. These findings proved the synergistic action of B. cereus KH1 with lipopeptide biosurfactant may accelerated the decolourisation efficiency to 87%.
Anode biofilm is a crucial component in microbial fuel cells (MFCs) for electrogenesis. Better knowledge about the biofilm development process on electrode surface is believed to improve MFC performance. In this study, double-chamber microbial fuel cell was operated with diluted POME (initial COD = 1,000 mg L(-1)) and polyacrylonitrile carbon felt was used as electrode. The maximum power density, COD removal efficiency and Coulombic efficiency were found as 22 mW m(-2), 70 and 24 %, respectively. FTIR and TGA analysis confirmed the formation of biofilm on the electrode surface during MFC operation. The impact of anode biofilm on anodic polarization resistance was investigated using electrochemical impedance spectroscopy (EIS) and microbial community changes during MFC operation using denaturing gradient gel electrophoresis (DGGE). The EIS-simulated results showed the reduction of charge transfer resistance (R ct) by 16.9 % after 14 days of operation of the cell, which confirms that the development of the microbial biofilm on the anode decreases the R ct and therefore improves power generation. DGGE analysis showed the variation in the biofilm composition during the biofilm growth until it forms an initial stable microbial community, thereafter the change in the diversity would be less. The power density showed was directly dependent on the biofilm development and increased significantly during the initial biofilm development period. Furthermore, DGGE patterns obtained from 7th and 14th day suggest the presence of less diversity and probable functional redundancy within the anodic communities possibly responsible for the stable MFC performance in changing environmental conditions.
This study aimed to enhance the crystallizability of bio-based succinic acid for its efficient recovery while maintaining the end product at the highest purity. Immobilization of Actinobacillus succinogenes was initially evaluated based on three different carriers: volcanic glass, clay pebbles, and silica particles. The adsorption capacity of metabolites with a low concentration (10 g/L) and a high concentration (40 g/L) was investigated. It was demonstrated that clay pebbles adsorbed the least succinic acid (
Continuous bio-production of succinic acid was reported in homogeneous solid dispersion (HSD) system utilizing porous coconut shell activated carbon (CSAC) as immobilization carrier. The aim of the present work was to implement the HSD system to increase the area of cell immobilization and the rate of succinic-acid production from the lignocellulosic medium. The ratio of the two enzymes (cellulase-to-hemicellulase) was initially optimized to break down the lignocellulose into its free monomers, wherein the best ratio was determined as 4:1. Succinic-acid production was evaluated in the HSD system by varying the substrate loading and dilution rate. The results showed that high productivities of succinic acid were obtained when 60 g/L glucose was fed over a dilution rates ranging from 0.03 to 0.4/h. The titer of succinic acid decreased gradually with higher dilution rate, whereas the residual substrate concentration increased with it. Critical dilution rate was determined to be 0.4/h at which the best productivity of succinic acid of 6.58 g/L h and its yield of 0.66 g/g were achieved using oil palm fronds (OPF) hydrolysate. This work lends evidence to the use of CSAC and lignocellulosic hydrolysate to further exploit the potential economies of scale.