Aim: To improve biosurfactant production economics by the utilization of potential low-cost materials.
Methods and Results:In an attempt to utilize cost-effective carbon sources in the fermentative production of biosurfactants, various pure and waste frying oils were screened by a standard biosurfactant producing strain. Considering the regional significance, easy availability and the economical advantages, waste frying coconut oil was selected as the substrate for further studies. On isolation of more competent strains that could use waste frying coconut oil efficiently as a carbon source, six bacterial strains were isolated on cetyltrimethyl ammonium bromide-methylene blue agar plate, from a soil sample collected from the premises of a coconut oil mill. Among these, Pseudomonas aeruginosa D was selected as the potential producer of rhamnolipid. Spectrophotometric method, TLC, methylene blue active substance assay, drop collapse technique, surface tension measurement by Du Nouy ring method and emulsifying test confirmed the rhamnolipid producing ability of the selected strain and various process parameters were optimized for the production of maximum amount of biosurfactant. Rhamnolipid components purified and separated by ethyl acetate extraction, preparative silica gel column chromatography, HPLC and TLC were characterized by fast atom bombardment mass spectrometry as a mixture of dirhamnolipids and monorhamnolipids. The rhamnolipid homologues detected were
The fermentative production of rhamnolipid biosurfactant from Pseudomonas aeruginosa MTCC 2297 was carried out by submerged fermentation using various cost-effective waste materials such as orange peelings, carrot peel waste, lime peelings, coconut oil cake, and banana waste. The orange peel was found to be the best substrate generating 9.18 g/l of rhamnolipid biosurfactant with a surface tension reduction up to 31.3 mN/m. The production was growth independent, and optimum conditions were standardized. The emulsifying activity was highest against kerosene (73.3%). Rhamnolipid components were purified and separated by ethyl acetate extraction, preparative silica gel column chromatography, high-performance liquid chromatography and thin-layer chromatography. The major rhamnolipid components were characterized, by fast atom bombardment mass spectrometry, as a mixture of dirhamnolipids and monorhamnolipids.
b-Glucosidases (b-D-glucoside glucohydrolase, 3.2.1.21) are a group of enzymes mainly involved in the hydrolysis of b-glycosidic bonds connecting carbohydrate residues in different classes of b-D glycosides. During cellulose degradation they convert cellobiose and cellooligosaccharides produced by the endo and exoglucanases to glucose. Most of the microbial b-glucosidases are inhibited by glucose. This limits their application in commercial scale cellulose degradation ventures. Solid state fermentation production of a highly glucose tolerant b-glucosidase by a novel isolate of Paecilomyces was optimized using a two step statistical experiment design. In the first step which employed a Plackett-Burman design, the effects of parameters such as moisture, temperature, pH, inoculum concentration, incubation time and different concentrations of (NH 4 ) 2 SO 4 , KH 2 PO 4 , NaCl, peptone and cellobiose were evaluated. The parameters with significant influence on the process were selected and fine tuned in the second step using a Box-Behnken design. The model obtained was validated and a peptone concentration of 2 g/ l, inoculum concentration of 1.2 9 10 6 spores/ml and an incubation period of 96 h were found to be optimum for the maximum production of the enzyme. The optimization resulted in a doubling of the enzyme production by the fungus.
Purpose
This paper aims to present experimental and numerical analyses of fused filament fabrication (FFF) printed parts and show how mechanical characteristics of printed ABS-MG94 (acrylonitrile butadiene styrene) are influenced by the void volume fraction, cooling rate and residual thermal stresses.
Design/methodology/approach
Printed specimens were experimentally tested to evaluate the mechanical properties for different printing speeds, and micrographs were taken. A thermo-mechanical finite element model, able to simulate the FFF process, was developed to calculate the temperature fields in time, cooling rate and residual thermal stresses. Finally, the experimental mechanical properties and the microstructure distribution could be explained by the temperature fields in time, cooling rate and residual thermal stresses.
Findings
Micrographs revealed the increase of void volume fraction with the printing speed. The variations on voids were associated to the temperature fields in time: when the temperatures remained high for longer periods, less voids were generated. The Young's Modulus of the deposited filament varied according to the cooling rate: it decreased when the cooling rate increased. The influence of the residual thermal stresses and void volume fraction on the printed parts failure was also investigated: in the worst scenarios evaluated, the void volume fraction reduced the strength in 9 per cent, while the residual thermal stresses reduced it in 3.8 per cent.
Originality/value
This work explains how the temperature fields can affect the void volume fraction, Young's Modulus and failure of printed parts. Experimental and numerical results are shown. The presented research can be used to choose printing parameters to achieve desired mechanical properties of FFF printed parts.
Alcaligenes sp. d(2) isolated from soil was earlier reported as a potent phenol-degrading organism. In the Fourier transform/infrared spectroscopic analysis of the biodegraded sample, the aromatic stretching was missing and the spectrum gave evidence for the presence of polyhydroxybutyric acid along with its depolymerized products. In the gas chromatogram of the biodegraded sample, the peak of phenol at 14.997 min was absent and there were many peaks after 20 min. The organism could carry out 100% degradation of phenol in 32 h and could progressively result in early accumulation of polyhydroxybutyrate (PHB) intracellularly from 8 h onwards. The various conditions optimized for the maximum accumulation of intracellular PHB were pH 7.0, incubation time 24 h, phenol concentration 15 mg/100 ml, and ammonium sulfate concentration 25 mg/100 ml.
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