Free and immobilized cultures of Spirulina maxima for swine waste treatment

We have analyzed the behavior of spirulina maxima at increasing concentration of ammonium nitrogen present in swine waste when it is either growing in suspension or immobilized in polymeric supports. We compared the response of spirulina maxima growth to different concentrations of aeration stabilized swine waste (total phosphorus, ammonium nitrogen) as a way to determine the treatment efficiency of both systems. At a dilution of 50 % of swine waste, the suspended system reached the best results for biomass concentration and nutrient removal. In the immobilized system, at dilutions of 25 and 50 % of swine waste, more than 90 % ammonium nitrogen removal was obtained, and the optimal cell concentration for immobilization was 2 g/l (wet basis).     

Ultracytochemical localization of dihydroorotate dehydrogenase in mitochondria and vacuoles ofSaccharomyces cerevisiae

The coenzyme-independent dihydroorotate dehydrogenase (EC 1.3.3.1) linking the pyrimidine biosynthetic pathway to the respiratory chain, was ultracytochemically localized by the tetrazolium method in derepressed exponential-phase cultures ofSaccharomyces cerevisiae. Biochemical analysis showed a considerable variation of this enzyme activity in inverse proportion to the aeration of the yeast cultures. The assay also showed that after prefixation of yeast cells with 1% glutaraldehyde at 0°C for 20 min, approximately one-half of the enzyme activity was preserved. The cytochemical reaction mixture contained dihydroorotate (2 mmol/L), thiocarbamyl nitroblue tetrazolium (0.44 mmol/L), phenazine methosulfate (0.16 mmol/L) and KCN (1.7 mmol/L) in Tris-HCl buffer (100 mmol/L) of pH 8.0. The osmicated formazan deposits featured envelopes of mitochondria and of nuclei and were prominent in the mitochondrial inclusions and in the vacuolar membranes. The latter sites of dihydroorotate dehydrogenase activity represent biosynthetic activity in yeast vacuoles, still generally assumed to function as yeast lysosomes and storage organelles. In the light of the generally observed invasions of juvenile yeast vacuoles into mitochondria, the enzymic sites observed in mitochondrial inclusion were considered as evidence of the interactions of yeast vacuoles and mitochondria. Transfer of vacuolar membranes with dihydroorotate dehydrogenase activity into mitochondrial matrix is suggested.     

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,...     

Short communication: Effect of water activity on cell growth and phenol oxidase production by Streptomyces cyaneus var. viridochromogenes in surface culture

In surface cultures of Streptomyces cyaneus var. viridochromogenes, NaCl depressed water activity (a _w) without supporting growth. Reducing a _w from 0.987 to 0.951 led to 3- and 4-fold increases in intracellular and extracellular phenol oxidase activities, respectively.     

Evaluation of coupling conditions for the incorporation of Nα-Fmoc-Tyr(PO3H2)-OH in solid-phase peptide synthesis

Summary In order to minimise the formation of the pyrophosphate derivative of the target peptide when side-chain-unprotected phopshotyrosine is used in solid-phase peptide synthesis, this building block can be incorporated using benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate/1-hydroxybenzotriazole/N-methylmorpholine (1:1:2.3) in the presence of a chaotropic salt (0.4 M LiCl in N-methyl-2-pyrrolidinone).Abbreviations BOP benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate - DIEA diisopropylethylamine - Fmoc 9-fluorenylmethoxycarbony - HATU N-[(dimethylamino)1H-1,2,3-triazolo[4,5-b]pyridin-1-ylmethylene]-N-methylmethan-aminium hexafluorophosphate N-oxide - HOBt 1-hydroxybenzotriazole - HPLC high-performance liquid chromatography - MALDI-TOF matrix-assisted laser-desorption ionization time-of-flight mass spectrometry - NMM N-methylmorpholine - NMP N-methyl-2-pyrrolidinone - Pmc 2,2,5,7,8-pentamethyl-chroman-6-sulfonyl - ® solid support - TFA trifluoroacetic acid - TPTU 2-(2-pyridon-1-yl)-1,1,3,3-tetramethyluroniumfluoroborate. Abbreviations used for amino acids follow the recommendations of the IUPAC-IUB Commission of Biochemical Nomenclature [Eur. J. Biochem., 138 (1984) 9]     

Factors controlling somatic embryogenesis

Histological and ultrastructural, molecular and elemental distribution changes were investigated during the induction of direct somatic embryogenesis using theCamellia japonica leaf culture system. In this culture system, direct somatic embryogenesis is induced in a controlled way in a specific leaf region (leaf blade) within a leaf. Embryogenic and non-embryogenic leaf regions have characteristic energy-dispersive X-ray spectra already before induction. According to these results electron probe X-ray microanalysis (EPMA) can be a tool for early diagnosis of embryogenic competence. Histological studies showed that severe fluctuations in the number of calcium oxalate crystals and in starch accumulation occur after induction but only in induced tissues. Changes in the cell wall composition of competent cells occur shortly after the induction treatment. The induction of morphogenesis is linked to the appearance of callose covering the surface cells of induced leaves and calluses. A 2^nd deposition of material (cutin) is necessary for normal somatic embryogenesis to occur. The involvement of lipid transfer proteins in the appearance of cutin in the embryogenic regions of the explant is suggested.     

Ultrastructural aspects of wheat straw degradation by Phanerochaete chrysosporium and Trametes versicolor

The ultrastructural patterns characterizing wheat straw degradation by the ligninolytic fungi Phanerochaete chrysosporium and Trametes versicolor were studied. During fungal attack, the less lignified tissues were degraded first, whereas the xylematic and sclerenchymatic fibers underwent a delayed attack. In straw samples degraded by T. versicolor, partial delignification, defibrillation and swelling of cell walls, often causing separation between primary and secondary walls, were observed. By contrast, the formation of erosions and fissures, with minor lignin removal, characterized the attack to the cell wall by P. chrysosporium. At an advanced stage of decay, KMnO₄ staining demonstrated abundant electron-dense material around hyphae and in the proximity of the cell-wall surface. In the case of P. chrysosporium, spherical black bodies were found in the erosions and fissures produced during fungal attack.     

Simple and non-radioactive method for determination of sialyltransferase activity

A new, non-radioactive and cheap colorimetric method for determination of activity of sialyltransferases of various specifities using natural substrates based on 2-thiobarbituric acid assay is presented. The assay was tested with three different sialyltransferases (a-2,3 and a-2,6) and compared with the radioactive assay.