Comparative growth of trichoderma strains in different nutritional sources, using bioscreen c automated system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Response surface optimization of D(-)-lactic acid production by Lactobacillus SMI8 using corn steep liquor and yeast autolysate as an alternative nitrogen source

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Very high gravity sucrose fermentation by Brazilian industrial yeast strains: effect of nitrogen supplementation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biomass production and secretion of hydrolytic enzymes are influenced by the structural complexity of the nitrogen source in Fusarium oxysporum and Aspergillus nidulans

The structural complexity of the nitrogen sources strongly affects biomass production and secretion of hydrolytic enzymes in filamentous fungi. Fusarium oxysporum and Aspergillus nidulans were grown in media containing glucose or starch, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids), peptides (peptone) and protein (gelatin). In glucose, when the initial pH was adjusted to 5.0, for both microorganisms, higher biomass production occurred upon supplementation with a nitrogen source in the peptide form (peptone and gelatin). With a close to neutrality pH, biomass accumulation was lower only in the presence of the ammonium salt. When grown in starch, biomass accumulation and secretion of hydrolytic enzymes (amylolytic and proteolytic) by Fusarium also depended on the nature of the nitrogen supplement and the pH. When the initial pH was adjusted to 5.0, higher growth and higher amylolytic activities were detected in the media supplemented with peptone, gelatin and casamino acids. However, at pH 7.0, higher biomass accumulation and higher amylolytic activities were observed upon supplementation with peptone or gelatin. Ammonium sulfate and casamino acids induced a lower production of biomass, and a different level of amylolytic enzyme secretion: high in ammonium sulfate and low in casamino acids. Secretion of proteolytic activity was always higher in the media supplemented with peptone and gelatin. Aspergillus, when grown in starch, was not as dependent as Fusarium on the nature of nitrogen source or the pH. The results described in this work indicate that the metabolism of fungi is regulated not only by pH, but also by the level of structural complexity of the nitrogen source in correlation to the carbon source.

Effect of sugar catabolite repression in correlation with the structural complexity of the nitrogen source on yeast growth and fermentation

Biomass and ethanol production by industrial Saccharomyces cerevisiae strains were strongly affected by the structural complexity of the nitrogen source during fermentation in media containing galactose, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Diauxie was observed at low galactose concentrations independent of nitrogen supplementation. At high sugar concentrations altered patterns of galactose utilisation were observed. Biomass accumulation and ethanol production depended on the nature of the nitrogen source and were different for baking and brewing ale and lager strains. Baking yeast showed improved galactose fermentation performance in the medium supplemented with casamino acids. High biomass production was observed with peptone and casamino acids for the ale brewing strain, however high ethanol production was observed only in the presence of casamino acids. Conversely, peptone was the nitrogen supplement that induced higher biomass and ethanol production for the lager brewing strain. Ammonium salts always induced poor yeast performance. The results with galactose differed from those obtained with glucose and maltose which indicated that supplementation with a nitrogen source in the peptide form (peptone) was more positive for yeast metabolism, suggesting that sugar catabolite repression has a central role in yeast performance in a medium containing nitrogen sources with differing levels of structural complexity.

Evaluation of Rice Bran Extract as a Nitrogen Source for Improved Hemicellulosic Ethanol Production from Sugarcane Bagasse by New Xylose-Fermenting Yeast Strains Isolated from Brazilian Forests

Xylose is the main sugar in hemicellulosic hydrolysates and its fermentation into ethanol by microorganisms is influenced by nutritional factors, such as nitrogen source, vitamins and other elements. Rice bran extract (RBE) is an inexpensive nitrogen source primarily consisting of high amount of protein. This study evaluates the potential of RBE as a nitrogen source for the hemicellulosic ethanol production from sugarcane bagasse dilute acid hydrolysate by novel yeast strains Scheffersomyces shehatae (syn. Candida shehatae) CG8-8BY and Spathaspora arborariae UFMG-HM19.1A, isolated from Brazilian forests. Two different media formulations were used for inoculum preparation and production medium, using yeast extract and RBE as nitrogen sources. S. shehatae CG8-8BY showed ethanol production of 17.0 g/l with the ethanol yield (0.33 g/g) and fermentation efficiency (64 %) from medium supplemented with RBE. On the other hand, S. arborariae presented 5.4 g/l of ethanol production with ethanol yield (0.14 g/g) and fermentation efficiency (21 %) in a fermentation medium supplemented with RBE. Appropriate media formulation is an important parameter to increase the productivity of bioconversion process and RBE proved to be an efficient and inexpensive nitrogen source to supplement sugarcane bagasse hemicellulosic hydrolysate for second generation ethanol production. © 2013 Society for Sugar Research & Promotion.

WHEAT NITROGEN FERTILIZATION UNDER NO TILL ON THE LOW ALTITUDE BRAZILIAN CERRADO

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fibrolytic enzyme production of Myceliophthora thermophila M.7.7. using inexpensive carbon sources and mineral nutrients

This study investigated the effect of inexpensive carbon and nitrogen sources on enzyme production by Myceliophthora thermophila M.7.7 in solid-state fermentation. Three kinds of lignocellulosic waste (corn straw, sugarcane bagasse and sugarcane straw) and six nitrogen sources (urea, calcium nitrate, analytical ammonium sulphate, yeast extract, agricultural fertilizer NPK 20-05-20 and fertilizing grade ammonium sulphate) were tested. Some physical-chermical parameters of the fermentation, such as temperature, initial pH and moisture content of the substrate on enzyme production, were evoluated. The maximum activities of xylanase (446.9 U/ml) endoglucanase (94.7 U/ml) and beta-glucosidase (2.8 U/ml) were observed in a mixture of corn straw and wheat bran (1:1 w/w) as the carbon source using fertilizer grade ammonium sulphate as the nitrogen source. This production occurred for an incubation period of 96 h, at 40°C, with initial moisture content of 70% and pH 5.0. These results have significant interest since they could be used for the future production of enzymes in a low-cost industrial process.

Chicken fat and inorganic nitrogen source for lipase production by Fusarium sp. (Gibberella fujikuroi complex)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of photobioreactor configuration, nitrogen source and light intensity on the fed-batch cultivation of Arthrospira (Spirulina) platensis. Bioenergetic aspects

Bioenergetic analysis may be applied in order to predict microbial growth yields, based on the Gibbs energy dissipation and mass conservation principles of the overall growth reaction. The bioenergetics of the photoautotrophic growth of the cyanobacterium Arthrospira (Spirulina) platensis was investigated in different bioreactor configurations (tubular photobioreactor and open ponds) using different nitrogen sources (nitrate and urea) and under different light intensity conditions to determine the best growing conditions in terms of Gibbs energy dissipation, number of photons to sustain cell growth and phototrophic energy yields distribution in relation to the ATP and NADPH formation, and release of heat. Although an increase in the light intensity increased the Gibbs energy dissipated for cell growth and maintenance with both nitrogen sources, it did not exert any appreciable influence on the moles of photons absorbed by the system to produce one C-mol biomass. On the other hand, both bioenergetic parameters were higher in cultures with nitrate than with urea, likely because of the higher energy requirements needed to reduce the former nitrogen source to ammonia. They appreciably increased also when open ponds were substituted by the tubular photobioreactor, where a more efficient light distribution ensured a remarkably higher cell mass concentration. The estimated percentages of the energy absorbed by the cell showed that, compared with nitrate, the use of urea as nitrogen source allowed the system to address higher energy fractions to ATP production and light fixation by the photosynthetic apparatus, as well as a lower fraction released as heat. The best energy yields values on Gibbs energy necessary for cell growth and maintenance were achieved in up to 4-5 days of cultivation, indicating that it would be the optimum range to maintain cell growth. Thanks to this better bioenergetic situation, urea appears to be a quite promising low-cost, alternative nitrogen source for Arthrospira platensis cultures in photobioreactors. (C) 2011 Elsevier Ltd. All rights reserved.

Carbon- and nitrogen-quality signaling to translation are mediated by distinct GATA-type transcription factors

The target of rapamycin (Tor) proteins sense nutrients and control transcription and translation relevant to cell growth. Treating cells with the immunosuppressant rapamycin leads to the intracellular formation of an Fpr1p-rapamycin-Tor ternary complex that in turn leads to translational down-regulation. A more rapid effect is a rich transcriptional response resembling that when cells are shifted from high- to low-quality carbon or nitrogen sources. This transcriptional response is partly mediated by the nutrient-sensitive transcription factors GLN3 and NIL1 (also named GAT1). Here, we show that these GATA-type transcription factors control transcriptional responses that mediate translation by several means. Four observations highlight upstream roles of GATA-type transcription factors in translation. In their absence, processes caused by rapamycin or poor nutrients are diminished: translation repression, eIF4G protein loss, transcriptional down-regulation of proteins involved in translation, and RNA polymerase I/III activity repression. The Tor proteins preferentially use Gln3p or Nil1p to down-regulate translation in response to low-quality nitrogen or carbon, respectively. Functional consideration of the genes regulated by Gln3p or Nil1p reveals the logic of this differential regulation. Besides integrating control of transcription and translation, these transcription factors constitute branches downstream of the multichannel Tor proteins that can be selectively modulated in response to distinct (carbon- and nitrogen-based) nutrient signals from the environment.

TnrA, a transcription factor required for global nitrogen regulation in Bacillus subtilis.

Expression of the Bacillus subtilis nrgAB operon is derepressed during nitrogen-limited growth. We have identified a gene, tnrA, that is required for the activation of nrgAB expression under these growth conditions. Analysis of the DNA sequence of the tnrA gene revealed that it encodes a protein with sequence similarity to GlnR, the repressor of the B. subtilis glutamine synthetase operon. The tnrA mutant has a pleiotropic phenotype. Compared with wild-type cells, the tnrA mutant is impaired in its ability to utilize allantoin, gamma-aminobutyrate, isoleucine, nitrate, urea, and valine as nitrogen sources. During nitrogen-limited growth, transcription of the nrgAB, nasB, gabP, and ure genes is significantly reduced in the tnrA mutant compared with the levels seen in wild-type cells. In contrast, the level of glnRA expression is 4-fold higher in the, tnrA mutant than in wild-type cells during nitrogen restriction. The phenotype of the tnrA mutant indicates that a global nitrogen regulatory system is present in B. subtilis and that this system is distinct from the Ntr regulatory system found in enteric bacteria.

Nitrogen metabolism in haloarchaea

The nitrogen cycle (N-cycle), principally supported by prokaryotes, involves different redox reactions mainly focused on assimilatory purposes or respiratory processes for energy conservation. As the N-cycle has important environmental implications, this biogeochemical cycle has become a major research topic during the last few years. However, although N-cycle metabolic pathways have been studied extensively in Bacteria or Eukarya, relatively little is known in the Archaea. Halophilic Archaea are the predominant microorganisms in hot and hypersaline environments such as salted lakes, hot springs or salted ponds. Consequently, the denitrifying haloarchaea that sustain the nitrogen cycle under these conditions have emerged as an important target for research aimed at understanding microbial life in these extreme environments. The haloarchaeon Haloferax mediterranei was isolated 20 years ago from Santa Pola salted ponds (Alicante, Spain). It was described as a denitrifier and it is also able to grow using NO3-, NO2- or NH4+ as inorganic nitrogen sources. This review summarizes the advances that have been made in understanding the N-cycle in halophilic archaea using Hfx mediterranei as a haloarchaeal model. The results obtained show that this microorganism could be very attractive for bioremediation applications in those areas where high salt, nitrate and nitrite concentrations are found in ground waters and soils.

Transcriptional profiles of Haloferax mediterranei based on nitrogen availability

The haloarchaeon Haloferax mediterranei is able to grow in the presence of different inorganic and organic nitrogen sources by means of the assimilatory pathway under aerobic conditions. In order to identify genes of potential importance in nitrogen metabolism and its regulation in the halophilic microorganism, we have analysed its global gene expression in three culture media with different nitrogen sources: (a) cells were grown stationary and exponentially in ammonium, (b) cells were grown exponentially in nitrate, and (c) cells were shifted to nitrogen starvation conditions. The main differences in the transcriptional profiles have been identified between the cultures with ammonium as nitrogen source and the cultures with nitrate or nitrogen starvation, supporting previous results which indicate the absence of ammonium as the factor responsible for the expression of genes involved in nitrate assimilation pathway. The results have also permitted the identification of transcriptional regulators and changes in metabolic pathways related to the catabolism and anabolism of amino acids or nucleotides. The microarray data was validated by real-time quantitative PCR on 4 selected genes involved in nitrogen metabolism. This work represents the first transcriptional profiles study related to nitrogen assimilation metabolism in extreme halophilic microorganisms using microarray technology.