Production and characterization of Gluconacetobacter xylinus bacterial cellulose using cashew apple juice and soybean molasses.

Bacterial cellulose (BC) has been largely used in biomedical and technological fields. The use of agro-industrial byproducts as alternative source of carbon and nitrogen in culture media reduces the BC cost production, adds value to the byproducts and minimizes the environmental impact. In this study, the use of cashew apple juice and soybean molasses were evaluated to produce BC by Gluconacetobacter xylinus in comparison to the usual Hestrin and Schramm medium (HS). BC produced in static cultivation was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The BC production (4.50 g L-1) obtained from the medium using cashew apple juice as carbon source (20 g L-1) with soybean molasses as nitrogen source (10 g L-1) was superior than HS medium (4.03 g L-1). Morphological analysis showed that bacterial celluloses produced with agro-industrial byproducts combined were similar to those found for the pellicle obtained from HS medium.

Lignin peroxidase from Streptomyces viridosporus T7A: enzyme concentration using ultrafiltration.

It is well known that lignin degradation is a key step in the natural process of biomass decay whereby oxidative enzymes such as laccases and high redox potential ligninolytic peroxidases and oxidases play a central role. More recently, the importance of these enzymes has increased because of their prospective industrial use for the degradation of the biomass lignin to increase the accessibility of the cellulose and hemicellulose moieties to be used as renewable material for the production of fuels and chemicals. These biocatalysts also present potential application on environmental biocatalysis for the degradation of xenobiotics and recalcitrant pollutants. However, the cost for these enzymes production, separation, and concentration must be low to permit its industrial use. This work studied the concentration of lignin peroxidase (LiP), produced by Streptomyces viridosporus T7A, by ultrafiltration, in a laboratory-stirred cell, loaded with polysulfone (PS) or cellulose acetate (CA) membranes with molecular weight cutoffs (MWCO) of 10, 20, and 50 KDa. Experiments were carried out at 25 degrees C and pH 7.0 in accordance to the enzyme stability profile. The best process conditions and enzyme yield were obtained using a PS membrane with 10 KDa MWCO, whereby it was observed a tenfold LiP activity increase, reaching 1,000 U/L and 90% enzyme activity upholding.

Effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A.

The effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A was studied in a bench-scale bioreactor using a previously optimized growth medium (0.65% yeast extract and 0.1% corn oil, pH 7.0) at 37 degrees C and natural pH. Airflow rates of 0.3, 1.0, and 1.5 vvm and a fixed agitation of 200 rpm were initially studied followed by 1.0 vvm and 200, 300, 400, and 500 rpm. The use of 1.0 vvm and 400 rpm increased enzyme concentration 1.8-fold (100-180 U/L) and process productivity 4.8-fold (1.4-6.7 U/[L h]) in comparison with the use of 200 rpm and 0.3 vvm. The inexpensive corn oil, used as carbon source, besides its antifoam properties, proved to be nonrepressive for enzyme production.

Corn oil favours protease production by Streptomyces viridosporus T7A

Besides of being largely used for antibiotic production, streptomyces have also been pointed out as good producers of enzymes with industrial interest such as protease. In this work, the effect of corn oil on protease production by S. virisdoporus T7A was investigated as part of a wide project for microbial protease production. Culture media contained 0.65(per cent) yeast as nitrogen source, corn oil or corn oil combined with 0.65(per cent) glucose as carbone source, plus mineral salts. In both cases, corn oil used in three differents concentrations, 0.1, 0.5 and 1(per cent) (p/V). All experiments were carried out in agitated flasks at 37§C for 105 hours. Higher protease activty (52 U/L) was obtained in medium containing 0.65(per cent) glucose and 1.0(per cent) corn oil as carbon sources. Protease activity responded positively to the increase in the medium C/N ratio, i.e., to the increment in oil concentration. Our results also suggested that corn oil favours enzyme stability during the fermentation.