Biosurfactants are chemical molecules produced by the microorganisms with potential for application in various industrial and environmental sectors. The production parameters and the physicochemical properties of a biosurfactant synthesized by Bacillus pumilus using different concentrations of vinasse and waste frying oil as alternative carbon sources were analyzed. The microorganism was able to grow and produce a biosurfactant using both the residues. The surface tension was reduced up to 45 mN/m and the maximum production of crude biosurfactant was 27.7 and 5.7 g/l for vinasse and waste frying oil, respectively, in concentration of 5%. The critical micelle concentration (CMC) results of 1.5 and 0.2 g/l showed the efficiency of the biosurfactant produced on both the substrates. The results showed that the alternative substrates could be used for the production of an efficient biosurfactant by B. pumilus. These properties have potential for industrial and environmental applications.

The aim of this work was to study the nutritional requirements of Zymomonas mobilis CCT 4494 for levan production in three chemically defined media. During the optimization of the fermentative process for the production of the exopolysaccharide, different concentrations of glucose, fructose and sucrose as carbon source and yeast extract as vitamin source were tested. Variations of incubation temperature and initial pH of the medium were observed. The results showed that medium containing 20.0% sucrose and 0.5% yeast extract, with initial pH of 7.0, incubated at 30°C gave a 43.0% yield of the biopolymer.

A bacterium isolated from soil contaminated by hydrocarbon was studied and, by biochemical tests and analysis of PCR, the presence of Bacillus pumilus was identified. The production of biosurfactant was optimized, test of oil degradation and antimicrobial activity determination. The results showed that pH 5.0 and 7.0, 72 h of fermentation, sucrose and sugar cane juice (2%) had best yields. The bacterium is able to degrade crude oil and displays bacteriostatic and fungistatic activity. From the analysis of proximate composition of biosurfactant found the presence of biopolymer formed by a lipopolysaccharide-protein complex.

Alginate is a biopolymer used for a variety of industrial applications, for example, in the textiles, cosmetics, foods, agricultural and biotechnological industries. This biopolymer is traditionally extracted from some brown seaweeds (Phaeophyceae) and can be produced by bacteria isolated from soil, as Azotobacter vinelandii, like capsular polysaccharide using glucose, sucrose, among others as carbon sources. The main difference between the alginate of seaweed and the bacterial ones, is the biggest degree of acetylation of this last one, with great influence in the gel force. These chemical characteristics and production of bacterial alginate are presented in this work.

Seis bactérias produtoras de polissacarídeos isoladas de amostras do solo (3B, 4B, 7B, 21B, 18E e 21D) pertencentes aos gêneros Pseudomonas e Arthrobacter, foram testadas quanto ao rendimento da produção de polissacarídeos em dois caldos de cultura: um com glicose e outro com sacarose, nas concentrações de 1, 2, 3, 4 e 5%. O rendimento foi calculado medindo-se a viscosidade dos caldos, através da equação de Poiseuille. Também foi verificado o efeito da temperatura de incubação (25, 30 e 35ºC) e o do pH (5, 6, 7 e 8) dos meios de cultura. Os resultados obtidos mostraram que concentrações da fonte de carbono até 2% apresentaram os maiores rendimentos do polissacarídeo. Glicose e sacarose estimularam a produção de polissacarídeos de forma similar. Quando o pH inicial do caldo de fermentação aumentou de 5,0 para 7,0 ocorreu um aumento da produção do polissacarídeo. Entretanto, valores mais altos (pH=8,0) causaram uma diminuição na formação do produto. Com relação à temperatura, 30ºC foi considerada ótima, pois temperaturas maiores ou menores do que esta exerceram um efeito negativo na produção do polissacarídeo.

Six polysaccharide-producing bacteria, isolated from soil samples and identified as Pseudomonas and Arthrobacter (Strains 3B, 4B, 7B, 21B, 18E and 21D), were tested for the yield of polysaccharides produced during growth in two culture media: one containing glucose and the other sucrose (1, 2, 3, 4 and 5%). The yield was quantified measuring the viscosity of the broth, using the Poiscuille equation. The effect of temperature and pH of the culture media was investigated. The largest polysaccharide yield was obtained when the concentration of the carbon source was lower than 2%. Glucose and sucrose stimulated the polysaccharide production in a similar way. When the initial pH of the fermentation broth was increased from 5.0 up to 7.0, there was an increase in polysaccharide production. However, higher values (pH=8.0) caused a decrease in polysaccharide production. With regard to temperature, 30ºC was shown to be optimum, since higher or lower temperatures had a negative effect on saccharide production.