Christian Oliveira Reinehr

Simultaneous production of lipases and biosurfactants by submerged and solid-state bioprocesses.

Lipases and biosurfactants are compounds produced by microorganisms generally involved in the metabolization of oil substrates. However, the relationship between the production of lipases and biosurfactants has not been established yet. Therefore, this study aimed to evaluate the correlation between production of lipases and biosurfactants by submerged (SmgB) and solid-state bioprocess (SSB) using Aspergillus spp., which were isolated from a soil contaminated by diesel oil. SSB had the highest production of lipases, with lipolytic activities of 25.22U, while SmgB had 4.52U. The production of biosurfactants was not observed in the SSB. In the SmgB, correlation coefficients of 91% and 87% were obtained between lipolytic activity and oil in water and water in oil emulsifying activities, respectively. A correlation of 84% was obtained between lipolytic activity and reduction of surface tension in the culture medium. The surface tension decreased from 50 to 28mNm(-1) indicating that biosurfactants were produced in the culture medium.

Semicontinuous cultivation of the cyanobacterium Spirulina platensis in a closed photobioreactor

The cultivation of photosynthetic microorganisms such as the cyanobacterium Spirulina platensis has been studied by researchers in many countries because these organisms can produce products with industrial potential. We studied the specific growth rate (µx, day-1) and productivity (Px, in mg/L/day of Spirulina platensis biomass, dry weight basis) of two S. platensis strains (LEB-52 and Paracas) growing in aerated semicontinuous culture in two-liter Erlenmeyer flasks for 90 days (2160 h) at 30°C under 2500 lux of illumination in a 12 h photoperiod. Independent of the S. platensis strain used we found that low biomass concentrations (0.50 g/L) and high renewal rates (50% v/v) resulted in a high specific growth rate (µx = 0.111 day-1) and high productivity (Px = 42.3 mg/L/day). These values are two to four times higher than those obtained in simple batch cultivation and indicate that the semicontinuous cultivation of S. platensis is viable.

Surface response methodology for the optimization of lipase production under submerged fermentation by filamentous fungi

A Plackett–Burman Factorial Design of 16 experiments was conducted to assess the influence of nine factors on the production of lipases by filamentous fungi. The factors investigated were bran type (used as the main carbon source), nitrogen source, nitrogen source concentration, inducer, inducer concentration, fungal strain (Aspergillus niger or Aspergillus flavus were selected as good lipase producers via submerged fermentation), pH and agitation. The concentration of the yeast extract and soybean oil and the pH had a significant effect (p < 0.05) on lipase production and were consecutively studied through a Full Factorial Design 23, with the concentration of yeast extract and pH being significant (p < 0.05). These variables were optimized using a central composite design, obtaining maximum lipolytic activities with the use of 45 g/L of yeast extract and pH 7.15. The statistical model showed a 94.12% correlation with the experimental data.

Production and Characterization of Lipases by Two New Isolates of Aspergillus through Solid-State and Submerged Fermentation

Due to the numerous applications of lipases in industry, there is a need to study their characteristics, because lipases obtained from different sources may present different properties. The aim of this work was to accomplish the partial characterization of lipases obtained through submerged fermentation and solid-state fermentation by two species of Aspergillus. Fungal strains were isolated from a diesel-contaminated soil and selected as good lipases producers. Lipases obtained through submerged fermentation presented optimal activities at 37°C and pH 7.2 and those obtained through solid-state fermentation at 35°C and pH 6.0. The enzymes produced by submerged fermentation were more temperature-stable than those obtained by solid-state fermentation, presenting 72% of residual activity after one hour of exposition at 90°C. Lipases obtained through submerged fermentation had 80% of stability in acidic pH and those obtained through solid-state fermentation had stability greater than 60% in alkaline pH.

Chromium (VI) biosorption and removal of chemical oxygen demand by Spirulina platensis from wastewater-supplemented culture medium

The inappropriate discharge of wastewater containing high concentrations of toxic metals is a serious threat to the environment. Given that the microalga Spirulina platensis has demonstrated a capacity for chromium VI (Cr (VI) biosorption, we assessed the ideal concentration of chromium-containing wastewater required for maximum removal of Cr (VI) and chemical oxygen demand (COD) from the environment by using this microalga. The Paracas and Leb-52 strains of S. platensis, with initial wastewater concentrations of 0%, 12.5%, 25%, and 50%, were cultured in Zarrouk medium diluted to 50% under controlled air, temperature, and lighting conditions. The cultures were maintained for 28 days, and pH, biomass growth, COD, and Cr (VI) were assessed. The wastewater concentration influenced microalgal growth, especially at high concentrations. Removal of 82.19% COD and 60.92% Cr (VI) was obtained, but the COD removal was greater than the Cr (VI) removal in both strains of S. platensis.

Production and purification of amylolytic enzymes for saccharification of microalgal biomass.

The aim of this study was the production of amylolytic enzymes by solid state or submerged fermentations (SSF or SF, respectively), followed by purification using chemical process or microfiltration and immobilization of purified enzymes in a polyurethane support. The free and immobilized enzymes obtained were used to evaluate enzymatic hydrolysis of the polysaccharides of Spirulina. Microfiltration of the crude extracts resulted in an increase in their specific activity and thermal stability at 40°C and 50°C for 24h, as compared to extracts obtained by SSF and SF. Immobilization of polyurethane purified enzyme produced yields of 332% and 205% for the enzymes obtained by SF and SSF, respectively. Free or immobilized enzymes favor the generation of fermentable sugar, being the application of the purified and immobilized enzymes in the hydrolysis of microalgal polysaccharides considered a promising alternative towards development of the bioethanol production process from microalgal biomass.

Biorremediação de solos contaminados com resíduos oleosos através de bioaumentação e atenuação natural

The potential for soil contamination by oil spills is growing, due to heavy industrialization and economic development of countries. Due to this fact, the bioremediation has become an alternative to remediate areas through the use of biological agents. Two microorganisms, isolated from a lipid-rich effluent, were used in the bioaugmentation of soils contaminated with diesel oil, lubricating oil and soybean oil. Natural attenuation tests were conducted as controls. The removal of diesel fuel at the time of 21 d were of 18.5%, 7.30% and 11.38%, respectively, for the bioaugmentation with isolated I1 and I2 and natural attenuation. The removal of lubricating oil were 41.6%, 14.16% and 6.91% respectively for the DOI: 10.5433/1679-0375.2012v33n1p73 1 Acadêmicas do Curso de Engenharia Ambiental, Universidade de Passo Fundo; maitcarla@gmail.com, 2 Acadêmicas do Curso de Engenharia Ambiental, Universidade de Passo Fundo; deia_derossi@hotmail.com 3 Mestrando do Programa de Pós-Graduação em Engenharia, Universidade de Passo Fundo; clineidalmagro@gmail.com 4 Docente do Curso de Engenharia Ambiental, Universidade de Passo Fundo; reinehr@upf.br 5 Docente do Programa de Pós-Graduação em Engenharia, Universidade de Passo Fundo; *lmcolla@upf.br

Selection of lipase-producing microorganisms through submerged fermentation.

Lipases are enzymes used in various industrial sectors such as food, pharmaceutical and chemical synthesis industries. The selection of microorganisms isolated from soil or wastewater is an alternative to the discovery of new species with high enzymes productivity and with different catalytic activities. In this study, the selection of lipolytic fungi was carried out by submerged fermentation. A total of 27 fungi were used, of which 20 were isolated from dairy effluent and 7 from soil contaminated with diesel oil. The largest producers were the fungi Penicillium E-3 with maximum lipolytic activity of 2.81 U, Trichoderma E-19 and Aspergillus O-8 with maximum activities of 2.34 and 2.03 U where U is the amount of enzyme that releases 1 μmol of fatty acid per min per mL of enzyme extract. The fungi had maximum lipolytic activities on the 4th day of fermentation.

Potential of Live Spirulina platensis on Biosorption of Hexavalent Chromium and Its Conversion to Trivalent Chromium

Microalga biomass has been described worldwide according their capacity to realize biosorption of toxic metals. Chromium is one of the most toxic metals that could contaminate superficial and underground water. Considering the importance of Spirulina biomass in production of supplements for humans and for animal feed we assessed the biosorption of hexavalent chromium by living Spirulina platensis and its capacity to convert hexavalent chromium to trivalent chromium, less toxic, through its metabolism during growth. The active biomass was grown in Zarrouk medium diluted to 50% with distilled water, keeping the experiments under controlled conditions of aeration, temperature of 30°C and lighting of 1,800 lux. Hexavalent chromium was added using a potassium dichromate solution in fed-batch mode with the aim of evaluate the effect of several additions contaminant in the kinetic parameters of the culture. Cell growth was affected by the presence of chromium added at the beginning of cultures, and the best growth rates were obtained at lower metal concentrations in the medium. The biomass removed until 65.2% of hexavalent chromium added to the media, being 90.4% converted into trivalent chromium in the media and 9.6% retained in the biomass as trivalent chromium (0.931 mg.g−1).

Spirulina platensis biomass composition is influenced by the light availability and harvest phase in raceway ponds

ABSTRACT The behavior of cyanobacteria and its potential use for biofuel production in scale-up conditions is a topic of growing importance. The aim of our work is to study the effects of illumination, stirring, and different growth phases on the cultivation of the cyanobacteria Spirulina platensis in 10 L raceways. The cultivations were carried out in a greenhouse under measured, but not controlled, illumination and in agitated raceways with stirring speeds varying from 0.1 to 0.4 m s−1, using culture media with nutrient depletion. At the end of the stationary phase (SP) and decline of culture, the biomass was harvested and used to determine the chemical composition. The stirring rate and the growing phase influenced the carbohydrate concentration. In both phases of cultivation, compared to high-speed stirring, stirring at lower speeds produced fewer carbohydrates in the culture. Biomass grown until the end of the SP with a stirring speed of 0.35 m s−1 had a carbohydrate content of 72%, which is very high compared to that reported in the literature. GRAPHICAL ABSTRACT