Maria Antonia Pedrine Colabone Celligoi

Influence of carbon source and the fermentation process on levan production by Zymomonas mobilis analyzed by the surface response method.

3) was used to analyze the effects of the type and concentration of the substrate, as well as the batch and fed batch processes. A complete second factorial design (2 2 ) was used to observe the importance of sugar cane juice. The results indicated that the batch process improved the levan production reaching 40.14 g/L. The addition of sugar cane juice was not statistically significant for levan formation, however sugar cane juice stimulated biomass, sorbitol and ethanol production. The best medium for levan production was 150 g/L sucrose in batch.

Effect of raffinose and ultrasound pulses on invertase release by free and immobilized Saccharomyces cerevisiae in loofa (Luffa cylindrica) sponge

ABSTRACT This study investigated the effect of raffinose and ultrasound pulses on invertase release from free S. cerevisiae and S. cerevisiae immobilized in Luffa cylindrica . The free cell culture was submitted to 2% raffinose pulse and irradiated for 2 minutes at 0.12 and 0.46 h -1 dilution rates. The immobilized cell culture was submitted to raffinose pulse and irradiated for 1, 2 and 4 minutes, at 0.10 h -1 dilution rate. In immobilized cells, the raffinose pulse increased the invertase activity from 5.38 to 7.27 U/mg. Ultrasound application in free cell culture at the 0.12 h -1 dilution rate gave the best results. The activity varied from 25.08 to 29.38 U/mg while the increase in immobilized cells was from 5.22 to 9.70 U/mg when sonicated for two minutes. These results showed that ultrasound application in continuous culture could have great potential for application in biotechnological techniques. Key words: Immobilization, invertase, Luffa cylindrica, raffinose, Saccharomyces cerevisiae , ultrasound

Sugar cane juice fermentation by Zymomonas mobilis CP4 subjected to inhibition by ethanol and high initial concentration of substrate

Sugar cane juice fermentation by Z. mobilis CP4 subject to stress by ethanol and high concentration of sucrose was investigated. Supplementation with saponifiable portion of soybean oil deodourising destillate (SOD) at 5; 10 and 15 mL/L.The ethanol production resulted values of 15.91; 16.99 and 15.63 g/L respectively. Values of Yp/s 0.35; 0.36 and 0.37 were achieved, which represented 20.69; 24.14 and 27.59% respectively higher when unsupplemented medium fermentation was carried out.

Edible films based on cassava starch and fructooligosaccharides produced by Bacillus subtilis natto CCT 7712

The objectives of this work were to produce fructooligosaccharides (FOSs) by using the microorganism Bacillus subtilis natto CCT 7712 and to employ these FOSs as a functional ingredient in cassava starch edible films, which were characterized according to their microstructure, mechanical and barrier properties. The produced FOSs could be easily dissolved, resulting in homogeneous filmogenic solutions, which were easily manipulated to obtain films by casting. FOSs were added in different concentrations (0, 1, 5 and 10g/100g solids), and glycerol was used as a plasticizer (20g/100g solids). All formulations resulted in films that had a good appearance and were easily removable from the plates without bubbles or cracks. The FOSs exerted a plasticizing effect on the starch films and decreased their glass transition temperature. The addition of FOSs resulted in higher solubility and elongation and a decreased water vapor permeability of the films. FOSs were shown to be a promising ingredient for use in edible starch films.

Synthesis of sorbitol by Zymomonas mobilis under high osmotic pressure

The bacterium Zymomonas mobilis presents potential for sorbitol production when grown in culture medium with high sugar concentration. Sorbitol is produced and accumulated in the periplasma of the bacterium to protect the cells from the harmful effects of high osmotic pressure that results from the action of invertase on sucrose. The conversion of sucrose into glucose and fructose increases the osmolarity of the medium. However, an excessive increase in the osmotic pressure may decrease the sorbitol production. In this work Saccharomyces cerevisiae invertase was added two media containing sucrose 200 and 300 g.L-1. Sorbitol production in sucrose at 200 g.L-1 was 42.35 and 38.42 g.L-1, with and without the invertase treatment, respectively. In the culture medium with 300 g.L-1 sucrose, production reached 60.4 g.L-1 and with invertase treatment was 19.14 g.L-1. These results indicated that the excessive rise in osmotic pressure led to a significant decrease in sorbitol production by the Zymomonas mobilis bacterium in the sucrose medium treated with invertase.

Influence of Ultrasound on Sorbitol Release by Zymomonas mobilis Grown on High Sucrose Concentration

A bacteria Zymomonas mobilis produtora de etanol, produz tambem varios subprodutos quando crescida em meio de sacarose, entre esses o sorbitol. O sorbitol e produzido pela enzima glicose-frutose oxidorredutase (GFOR) presente no periplasma da bacteria, a funcao fisiologica da enzima e estabelecer a regulacao do equilibrio osmotico, quando a celula e crescida em meio com altas concentracoes de acucares. A enzima produz sorbitol e este e acumulado, como um soluto compativel a alta concentracao de acucar fora da celula. Este trabalho investigou efeito da aplicacao de ultra-som de baixa intensidade na liberacao de sorbitol de celulas de Zymomonas mobilis crescida em meio com sacarose a 200 g/L ate 48 h de fermentacao. A melhor producao de sorbitol foi de 36,09 g/L em 36 h de cultivo. A irradiacao ultra-sonica nao alterou os valores de sorbitol detectados e o ultra-som levou ao rompimento das celulas apos 20 min de tratamento.

Levan from Bacillus subtilis Natto: its effects in normal and in streptozotocin-diabetic rats

Levan is an exopolysaccharide of fructose primarily linked by β-(2→6) glycosidic bonds with some β-(2→1) branched chains. Due to its chemical properties, levan has possible applications in both the food and pharmaceutical industries. Bacillus subtilis is a promising industrial levan producer, as it ferments sucrose and has a high levan-formation capacity. A new strain of B. subtilis was recently isolated from Japanese food natto, and it has produced levan in large quantities. For future pharmaceutical applications, this study aimed to investigate the effects of levan produced by B. subtilis Natto, mainly as potential hypoglycemic agent, (previously optimized with a molecular weight equal to 72.37 and 4,146 kDa) in Wistar male rats with diabetes induced by streptozotocin and non-diabetic rats and to monitor their plasma cholesterol and triacylglycerol levels. After 15 days of experimentation, the animals were sacrificed, and their blood samples were analyzed. The results, compared using analysis of variance, demonstrated that for this type of levan, a hypoglycemic effect was not observed, as there was no improvement of diabetes symptoms during the experiment. However, levan did not affect any studied parameters in normal rats, indicating that the exopolysaccharide can be used for other purposes.

Optimization of the production of α-L-rhamnosidase by Aspergillus niger in solid state fermentation using agro-industrial residues.

ABSTRACT The enzyme α-L-rhamnosidase specifically cleaves terminal rhamnose residues from awide variety of natural products. This property endows this enzyme with importantbiotechnological potential as L-rhamnosidase could be employed in a variety ofapplications, including removing bitterness from citrus fruit juices, improving the aroma ofwines and converting clinically important steroids. This work optimized α-L-rhamnosidasesolid-state fermentation production from Aspergillus niger 426 using statistical methods.Firstly, a statistical mixture-design with three components to determine the best ratio ofnutrients for enzyme production was carried out. The optimal conditions consisted ofgrowing the fungi in media containing 0.14 g of cane sugar bagasse, 1.25 g of soybeanhulls and 3.05 g of rice straw; these conditions achieved a maximum α-L-rhamnosidaseactivity of 1.92 U / mL. Next, a 3² Box-Behnken design to optimize culture moisture levelsand nutrient solution pH values for enzyme production was carried out. α-L-rhamnosidaseactivity increased to 3.02 U / mL when medium moisture was 75.5% and pH value of4.0.Original Research Article

Effects of different nitrogen sources on the production of Hyaluronic acid by Streptococcus

Hyaluronic acid (HA) is a linear polysaccharide with high molecular weight composed of disaccharide units of D-glucuronic acid (GlcUA) and N-acetylglucosamine (GlcNAc). HA is naturally present in vertebrate organisms, as well as in bacteria. HA can be obtained commercially through three routes: human umbilical cords, rooster combs, and strains of group C Streptococcus .T his is an atural polysaccharide with extensive range of applications in the medical, pharmaceutical and cosmetics. Due to the viscoelastic and hydrophilic, the HA products and derivatives present high aggregated value ranging from US

Effect of carbon source on lipase production by Aeromonas sp. isolated from dairy effluent

2000 to 60000 Kg -1 , depending on their applications. The most frequently used bacteria in the industrial production of HA are Lancefield group A and C streptococci. These bacteria are nutritionally fastidious microorganisms which require complex nutrients due to their limited ability to synthesize specific aminoacids and B-vitamins. Additionally, there is the nutritional requirement with respect to organic nitrogen, which also supplies a large portion of carbon for their cellular biosynthesis. Recent studies seek alternatives to allow the cost of production of HA using agricultural derivatives and industrial waste. In this context, the objective of this study was to evaluate the effect of nitrogen sources yeast extract, soy protein, whey protein and corn steep liquor in the production of HA. Fermentations were carried out in 125 mL erlenmeyer flasks containing 25 mL culture medium. The culture medium comprised in ( gL -1 ): glucose, 30; nitrogen source (yeast extract, soy protein, whey protein or corn steep liquor), 30; K2HPO4 ,2 .5, NaCl, 2,0 and MgSO4 ,1 .5. The inoculum was 10% (v/v) and the fermentations occurred at 100 rpm, 37°C and pH 8.0 for 24 hours. The fermented medium was centrifuged and the cell free supernatant was treated with ethanol for the precipitation of HA which quantified using a colorimetric reagent Carbazole. The concentration of lactic acid, acetic acid and formic acid were also analyzed in a system of high performance liquid chromatography with IR detector, column Aminex HPX 87H at 60°C and a solution of H2SO4 0.005 mol L -1 as the mobile phase a flow rate of 0.7 mL min -1 . The results performed in triplicate were compared by the Tukey test at 5% probability level (p < 0.05). The highest production of HA, 0.534 g L -1 was obtained when using yeast extract as nitrogen source. Subsequently, experiments which resulted in a better yield of the polymer are those containing soybean protein (0.192 g.L -1 ) and whey protein ( 0.063 g.L -1 ). In medium containing corn steep liquor, no microbial growth or production of HA ocurred. The decreased production of HA was directly followed by a reduction of the production of lactic acid and acetic acid.