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Temperature increase may influence competition among phytoplankton species, potentially intensifying cyanobacteria blooms that can be favored by direct and indirect effects of temperature. In this study, we aimed to clarify how cyanobacteria can be favored by the direct effects of increased temperature compared to diatoms and chlorophytes. Strains of the most representative species of a eutrophic coastal lagoon (Microcystis aeruginosa, Planktothrix agardhii, Desmodesmus communis, and Cyclotella meneghiniana) were used to test the hypothesis that cyanobacteria would be favored by the direct effect of temperature increase. First, we evaluated the effect of temperature increase on growth in monocultures (batch and chemostats) at 25 and 30 °C and after in mixed cultures (chemostats). In batch monocultures, the cyanobacteria showed higher growth rates in 30 °C than in 25 °C. However, in continuous culture experiments (chemostats), growth rates of M. aeruginosa and P. agardhii were not affected by temperature, but the strains showed higher biovolume in steady-state with the temperature increase. In continuous mixed cultures, M. aeruginosa was always dominant and C. meneghiniana was excluded, regardless of temperature tested. D. communis was able to coexist with lower biomass. This study shows that rising temperatures can be detrimental to diatoms, even for a tropical strain. Although some studies indicate that the dominance of cyanobacteria in warmer climates may be due to the indirect effect of warming that will promote physical conditions in the environment more favorable to cyanobacteria, the outcomes of mixed cultures demonstrate that the direct effect of temperature can also favor the dominance of cyanobacteria.

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Background: Inulinases have been extracted and characterized from inulin-storing tissues; however, production of microbial inulinases have recently draw much attention as they offer several industrial advantages. Many microorganisms, including filamentous fungi, yeast and bacteria have been claimed as inulinase producers. These hydrolases are usually inducible and their exo-acting forms may hydrolyze fructose polymers (inulin) and oligosaccharides such as sucrose and raffinose. Fungal inulinase extracts are often produced as stable mixture of highly active fructanhydrolases. From a practical prospective, the best known inulinases to date are those produced by species of Penicillium, Aspergillus and Kluyveromyces. Results: The production of extracellular inulinase by A. kawachii in liquid cultures, using either inulin or yacon derived materials as CES as well as inulinase inducers, is reported. In addition, a partial characterization of the enzyme activity is included. Conclusions: Yacon derived products, particularly yacon juice, added to the culture medium proved to be a good CES for fungal growth as well as an inducer of enzyme synthesis. Partial characterization of the enzyme revealed that it is quite stable in a wide range of pH and temperature. In addition, characterization of the reaction products revealed that this enzyme corresponds to an exo-type. These facts are promising considering its potential application in inulin hydrolysis for the production of high fructose syrups.

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Se estudió la actividad fermentativa de Hanseniaspora uvarum RIVE 6-2-2 con el objetivo de evaluar su importancia en los procesos de producción de bebidas fermentadas. La cepa se cultivó en frascos Erlenmeyer conteniendo jugo de manzana esterilizado y sin aroma, y se determinaron los compuestos químicos de importancia sensorial producidos durante la fermentación en cultivo agitado (200 min-1) y estático (sin agitación). Los resultados mostraron que la cepa fue capaz de producir etanol hasta 4,02±0,1v/v% en cultivo estático a 28 °C. La agitación del medio de cultivo incrementó la producción de alcoholes superiores (hasta 488,2 mg/L) y ácido acético (468,0±10,2 mg/L) comparado al cultivo estático, mientras que por el contrario, la producción de etil acetato y glicerol (189,0±12,0 mg/L y 3,2±0,3 g/L) resultó ser mayor que en cultivo agitado (142,0±8,0 mg/L y 2,3±0,25 g/L) respectivamente. Cultivos bacth realizados adicionalmente reportaron una tasa de crecimiento (μ) de 0,05 h-1 y producción de pequeñas cantidades de compuestos típicamente encontrados en la fermentación alcohólica. Los mejores resultados, en términos de calidad organoléptica (aroma, sabor y olor), se obtuvieron en la fermentación en cultivo estático. El control de la aireación del medio de fermentación es una herramienta importante para controlar la síntesis de compuestos de importancia sensorial en la producción de bebidas fermentadas.

The fermentation activity of Hanseniaspora uvarum RIVE 6-2-2 was studied with the purpose of evaluating its importance in the production process of fermented beverages. The strain was cultured in Erlenmeyer flasks, which contained sterilized and odorless apple juice, and the chemical compounds of sensorial importance produced during fermentation in shaken (200 min-1), and static (without shaking) cultures at 28 ºC were determined. The results showed that the strains were capable of producing ethanol up to 4.20±0.1v/v% in static cultures at 28 ºC. Shaking of the culture medium increased the superior alcohol production (up to 488.2 mg/L) and acetic acid (468.0± 10.2 mg/L), when compared with the static culture; on the other hand, the production of ethyl acetate and glycerol (189.0±12.0 mg/L and 3.2±0.3 g/L) was higher in static than in shaken cultures (142.0±8.0 mg/L and 2.3±0.25 g/L), respectively. Additional batch cultures reported a growth rate (µ) of 0.05 h-1 and production of small amounts of compounds typically found in alcoholic fermentation. The best results, in terms of organoleptic qualities (aroma, taste and smell), were found in the static culture fermentation. The aeration control of the fermentation medium is an important tool for controlling the synthesis of sensorial importance compounds in the production of fermented beverages.

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Aiming at the industrial production of serogroup C meningococcal vaccine, different experimental protocols were tested to cultivate Neisseria meningitidis C and to investigate the related organic acid release. Correlations were established between specific rates of acetic acid and lactic acid accumulation and specific growth rate, during cultivations carried out on the Frantz medium in a 13 l bioreactor at 35°C, 0.5 atm, 400 rpm and air flowrate of 2 l min-1. A first set of nine batch runs was carried out: (1) with control of dissolved oxygen (O2) at 10% of its saturation point, (2) with control of pH at 6.5, and (3) without any control, respectively. Additional fed-batch or partial fed-batch cultivations were performed without dissolved O2 control, varying glucose concentration from 1.0 to 3.0 g l -1, nine of which without pH control and other two with pH control at 6.5. No significant organic acid level was detected with dissolved O 2 control, whereas acetic acid formation appeared to depend on biomass growth either in the absence of any pH and dissolved O2 control or when the pH was kept at 6.5. Under these last conditions, lactic acid was released as well, but it did not seem to be associated to biomass growth. A survey of possible metabolic causes of this behavior suggested that N. meningitidis may employ different metabolic pathways for the carbon source uptake depending on the cultivation conditions.

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