José D. Fontana

Acetobacter cellulose pellicle as a temporary skin substitute

A bacterial strain with morphological and biochemical properties close toAcetobacter xylinum has been cultured in nonagitated, inverted sucrose- and yeast water-based medium for the production of thick, smooth, and floating cellulosic pellicles. The cellulose content (>90%, dry weight, depending on the efficiency of water washing) and theβ-d-homopolyglucan nature of these pellicles were assessed by physical, chemical, and enzymatic methods. The apyrogenic bacterial biomass, a minor component of the dried biofilm (BioFill®), is inactivated by ethylene dioxide. Once applied on exudating or bloody tissues, this biofilm displays several advantages as a biological dressing, and hence, it is valuable as a temporary skin substitute in the treatment of skin wounds, such as burns, ulcers, grafts, and as an adjuvant in dermal abrasions.

Recent Developments in Microbial Inulinases Its Production, Properties, and Industrial Applications

Microbial inulinases are an important class of industrial enzymes that have gained much attention recently. Inulinases can be produced by a host of microorganisms, including fungi, yeast, and bacteria. Among them, however, Aspergillus sp. (filamentous fungus) and Kluyveromyces sp. (diploid yeast) are apparently the preferred choices for commercial applications. Among various substrates (carbon source) employed for their production, inulin-containing plant materials offer advantages in comparison to pure substrates. Although submerged fermentation has been universally used as the technique of fermentation, attempts are being made to develop solidstate fermentation technology also. Inulinases catalyze the hydrolysis of inulin to d-fructose (fructose syrup), which has gained an important place in human diets today. In addition, inulinases are finding other newer applications. This article reviews more recent developments, especially those made in the past decade, on microbial inulinases—its production using various microorganisms and substrates. It also describes the characteristics of various forms of inulinases produced as well as their applications.

Production of fumaric acid by fermentation of enzymatic hydrolysates derived from cassava bagasse

Abstract Cassava bagasse is a starch-rich lignocellulosic residue (50% of starch, by weight, on a dry basis) which is discarded daily into rivers. The enzymatic hydrolysate of cassava bagasse was used as the sole carbon source to produce fumaric acid by submerged fermentation using several Rhizopus strains. This work was developed in several steps. Six different sources of nitrogen and six different compositions of the enzymatic hydrolysate were used. An experimental design was carried out to optimize the media cultivation. The strain Rhizopus formosa MUCL 28422 was selected as the best fumaric acid producer, yielding 21.28 g/l in a media containing cassava bagasse as the sole carbon source, KNO 3 as nitrogen source (C/N ratio of 168), 20 g/l of CaCO 3 , 10 μg/l of biotin, 0.04 g/l of ZnSO 4 .7H 2 O, 0.25 g/l of MgSO 4 .7H 2 O, 0.15 g/l of KH 2 PO 4 and 15 ml/l of methanol.

Brazilian Bioethanol Program

Brazil is the largest producer of bioethanol, and sugarcane is the main raw material. Bioethanol, is produced by both batch and continuous processes, and in some cases, flocculating yeast is use. This article analyzes the Bracilian Ethanol Program. for the 1996–1997 havest, Brazil produced 14.16 billion L of ethanol and 13.8 million metrict of sugar, from 286 million metrict of sugarcane. These products were produced by 328 industries inactivity, with 101 autonomousethanol plants producing only ethanol, and 227 sugar mills producing sugar and ethanol. The sugar-ethanol market reaches about 7.5 billion US

Microbial degradation of hemicellulosic materials

/yr, accounting for direct and indirect revenues.

Nature of plant stimulators in the production of Acetobacter xylinum ("tea fungus") biofilm used in skin therapy.

Biodegradation of hemicelluloses requires enzyme activities that remove nonxylose substituents from the xylan backbone in addition to endoxylanases and β-xylosidases. Activities removing o-acetyl, arabinose, cinnamic acid-based esters, and uronic acid substituents occurred inStreptomyces olivochromogenes, Aspergillus niger, andSchizophyllum commune. 4-O-Methylglucuronidase was coinduced with other substituent-hydrolyzing enzymes when appropriate lignocellulosic materials were provided. Fractionation of crude enzymes indicated that the 4-o-methylglucuronidases were polydisperse. The 4-o-methylglucuronidases fromS. commune andA. niger acted on high molecular weight heteroxylans, but those from S.olivochromogenes functioned only with small, endo-β-(1,4)-xylanse-solubilized fragments.

Bioproduction of carotenoids: The comparative use of raw sugarcane juice and depolymerized bagasse by Phaffia rhodozyma

Caffeine and related xanthines were identified as potent stimulators for the bacterial cellulose production in A. xylinum. These compounds are present in several plants whose infusions are useful as culture-medium supplements for this acetobacterium.The proposed target for these native purine-like inhibitory substances is the novel diguanyl nucleotide phosphodiesterase(s) that participate(s) in the bacterial cellulogenic complex.A better understanding of this feature of A. xylinum physiology may facilitate the preparation of bacterial cellulose pellicles, which are applied as a biotechnological tool in the treatment of skin burns and other dermal injuries.

A factorial approach for a sugarcane juice-based low cost culture medium: increasing the astaxanthin production by the red yeast Phaffia rhodozyma

Brown sugar, raw sugarcane juice, and enzymatic hydrolyzates from amilaceous or ligno(hemi)cellulosic sources like cane bagasse turned out to be a minimal but satisfactory culture medium for the production of astaxanthin in Phaffia rhodozyma. The condition for this was a small supplementation (1 g/l) of a nitrogen source. Urea resulted in a preferential yeast biomass increase as compared to soya meal and tannery shavings, the major beneficial effect of which was in the pigment content of the yeast cells.

Acetobacter Cellulosic Biofilms Search for New Modulators of Cellulogenesis and Native Membrane Treatments

Abstract A sugarcane juice-based low cost culture medium was previously explored to produce the carotenoid pigment astaxanthin in liquid culture by the red yeast Phaffia rhodozyma (1300 μg astaxanthin/g of dry yeast and 6500 μg/l whole culture medium). Two peculiar limitations in Phaffia are growth temperature (<26 °C) and lack of sugar osmotolerance. Two advantages are the wide biochemical ability for the assimilation and metabolization of disaccharides and the prompt utilization of simple nitrogen sources. For instance, the sucrolytic/ureolytic enzymatic activities deserves exploration. In order to improve the culture medium composition and the conditions of fermentation for highly oxygenated carotenoids (e.g., astaxanthin) a study was carried out with a factorial design in two steps. As a first step, the production of astaxanthin was studied as a function of the nutrient concentration levels and their interactions. The production increase (μg/l) obtained was 23.0% but at the expense of 16.0% pigment content decrease (μg/g). In the second step, the variables pH and agitation level (OTR, oxygen transfer rate) were optimized and then, both goals were attained: the increase of pigment content (418 μg astaxanthin/g of yeast) as well as the absolute pigment production enhancement (1987 μg/l).

Screening of Bothrops snake venoms for L-amino acid oxidase activity

Since natural substances like pseudoxanthins exert a positive effect on the cellulogenic ability ofAcetobacter xylinum when producing cellulosic pellicles suitable for skin burn therapy, new defined and complex modulators were sought. Ca2+ and Mg2+ (4 mM) were strongly stimulatory. Na+ had no effect and K+ was inhibitory. Ammonium dihydrogen phosphate (0.12 g/L) ensured the same nitrogen supply as the same concentration of yeast extract as measured by cellomembrane dry wt./yield albeit higher yeast extract supplies produced thicker membranes. Corn steep liquor (CSL) was also progressively beneficial from 0.125 to 0.5 mL/L, and this yield could be further improved by the combination of CSL with a tea infusion (source of caffeine). Uridine (precursor for UDP-Glc, sugar donor in cellulose biosynthesis), guanine, guanosine, and its butirylated derivatives (precursors for the positive modulator of cellulose synthetase, di-cGMP) resulted in only moderate stimulation. Sodium phytate and betaine were also slightly stimulatory. The fibrilar product from a newAcetobacter isolate (Ax-M) was characterized as cellulose by comparison with the solid-state13C-NMR of algal cellulose. Its X-ray diffractogram was a confirmatory analysis. After incorporation of tamarind xyloglucan to previously air-dried cellulosic pellicles, diffractometry displayed only slight differences. Mercerized (5M NaOH) fresh cellulosic biofilms underwent drastic size reduction (3.5-fold), turning compact nut still flexible if maintained wet.