Purification, molecular properties and specificity of a thermoactive and thermostable proteinase from Pyrococcus abyssi, strain st 549, hyperthermophilic archaea from deep-sea hydrothermal ecosystem

Inactivation of lectins from castor cake by alternative chemical compounds

Enabling the use of castor cake in animal feeding is an excellent alternative strategy to reduce feed costs. The cake is a by-product derived from the extraction of the castor oil by the biodiesel industry whose chemical composition is satisfactory despite the presence of antinutritional factors like toxic lectins, which require detoxification before it can be used as a dietary ingredient. The aim of the present study was to evaluate alternative chemical sources in the degradation and inactivation of ricin and Ricinus communis agglutinin (RCA), two lectins from castor cake. Ten chemical compounds were evaluated: sodium hydroxide, monodicalcium phosphate, dicalcium phosphate, calcium oxide, calcium hydroxide, calcitic limestone, magnesian limestone, urea, potassium chloride, and sodium chloride. Gel electrophoresis indicated 100% lectin degradation only in the cakes treated with 90 g sodium hydroxide and 2500 mL water per kg of cake. The hemagglutination assay was crucial to providing innocuousness to the treated cakes, with total absence of hemagglutinating activity observed in the castor cakes treated with 60 or 90 g sodium hydroxide in water volumes equal to or higher than 1500 mL/kg of castor cake and in the cakes treated with 90 g calcium oxide with 2500 or 3000 mL water/kg castor cake. Thus, though depending on the concentration of the chemical compound and on the volume of water per kilogram of treated cake, sodium hydroxide and calcium oxide showed to be promising chemical products for degradation and complete inactivation of the lectins present in castor cake to allow its use as an ingredient in animal diets.

A new pepstatin-insensitive thermopsin-like protease overproduced in peptide-rich cultures of Sulfolobus solfataricus

In this study, we gain insight into the extracellular proteolytic system of Sulfolobus solfataricus grown on proteinaceous substrates, providing further evidence that acidic proteases were specifically produced in response to peptide-rich media. The main proteolytic component was the previously isolated SsMTP (Sulfolobus solfataricus multi-domain thermopsin-like protease), while the less abundant (named SsMTP-1) one was purified, characterized and identified as the sso1175 gene-product. The protein revealed a multi-domain organization shared with the cognate SsMTP with a catalytic domain followed by several tandemly-repeated motifs. Moreover, both enzymes were found spread across the Crenarchaeota phylum and belonging to the thermopsin family, although segregated into diverse phylogenetic clusters. SsMTP-1 showed a 75-kDa molecular mass and was stable in the temperature range 50–90 °C, with optimal activity at 70 °C and pH 2.0. Serine, metallo and aspartic protease inhibitors did not affect the enzyme activity, designating SsMTP-1 as a new member of the pepstatin-insensitive aspartic protease family. The peptide-bond-specificity of SsMTP-1 in the cleavage of the oxidized insulin B chain was uncommon amongst thermopsins, suggesting that it could play a distinct, but cooperative role in the protein degradation machinery. Interestingly, predictions of the transmembrane protein topology of SsMTP and SsMTP-1 strongly suggest a possible contribution in signal-transduction pathways.

Canola Cake as a Potential Substrate for Proteolytic Enzymes Production by a Selected Strain of Aspergillus oryzae: Selection of Process Conditions and Product Characterization

Oil cakes have excellent nutritional value and offer considerable potential for use in biotechnological processes that employ solid-state fermentation (SSF) for the production of high value products. This work evaluates the feasibility of using canola cake as a substrate for protease production by a selected strain of Aspergillus oryzae cultivated under SSF. The influences of the following process parameters were considered: initial substrate moisture content, incubation temperature, inoculum size, and pH of the buffer used for protease extraction and activity analysis. Maximum protease activity was obtained after cultivating Aspergillus oryzae CCBP 001 at 20°C, using an inoculum size of 10(7) spores/g in canola cake medium moistened with 40 mL of water to 100 g of cake. Cultivation and extraction under selected conditions increased protease activity 5.8-fold, compared to the initial conditions. Zymogram analysis of the enzymatic extract showed that the protease molecular weights varied between 31 and 200 kDa. The concentrated protease extract induced clotting of casein in 5 min. The results demonstrate the potential application of canola cake for protease production under SSF and contribute to the technological advances needed to increase the efficiency of processes designed to add value to agroindustrial wastes.

Purification and characterization of a salt-activated and organic solvent-stable heterotrimer proteinase from Virgibacillus sp. SK33 isolated from Thai fish sauce

A NaCl-activated proteinase produced by Virgibacillus sp. SK33 was purified to homogeneity using phenyl-Sepharose and Sephadex G-75 with a yield of 12% and purification of 2.6-fold. A single protein was detected at approximately 32 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, three subunits with molecular weights of 27,858, 33,918, and 35,368 Da were obtained from MALDI-TOF mass spectra, implying that the enzyme was a heterotrimer. The isoelectric point of the proteinase was 5.4. Optimum catalytic activity was at 55 degrees C and pH 7.5. The enzyme showed serine characteristics as it was completely inhibited by phenylmethanesulfonyl fluoride. The purified proteinase showed broad specificity toward oxidized insulin B including Gln4, Cys7, Glu13, Ala14, Leu15,17, Tyr16,26, Arg22, Phe24,25, and Lys29. Dominant cleavage sites of the enzyme were Tyr16-Leu17 and Phe25-Tyr26, indicating that it preferably hydrolyzed aromatic amino acids located on the P1 site. Among various substrates studied, the enzyme hydrolyzed anchovy protein to the greatest extent at 4 M NaCl. Activity increased with either CaCl2 or NaCl concentration with the maximum 2-fold increase at either 50 mM CaCl2 or 4 M NaCl. The enzyme was also highly stable up to 500 mM CaCl2 or 4 M NaCl. The proteinase showed high stability in various organic solvents (25%, v/v) including dimethylsulfoxide, methanol, acetonitrile, and ethanol. Results of peptide mass fingerprint and de novo peptide sequencing showed that the purified proteinase is a novel proteinase. The proteinase from Virgibacillus sp. SK33 could have a potential application in high ionic strength environments and aqueous-organic solvent systems.

Biodiversity of thermophilic prokaryotes with hydrolytic activities in hot springs of Uzon Caldera, Kamchatka (Russia)

Samples of water from the hot springs of Uzon Caldera with temperatures from 68 to 87 degrees C and pHs of 4.1 to 7.0, supplemented with proteinaceous (albumin, casein, or alpha- or beta-keratin) or carbohydrate (cellulose, carboxymethyl cellulose, chitin, or agarose) biological polymers, were filled with thermal water and incubated at the same sites, with the contents of the tubes freely accessible to the hydrothermal fluid. As a result, several enrichment cultures growing in situ on different polymeric substrates were obtained. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments obtained after PCR with Bacteria-specific primers showed that the bacterial communities developing on carbohydrates included the genera Caldicellulosiruptor and Dictyoglomus and that those developing on proteins contained members of the Thermotogales order. DGGE analysis performed after PCR with Archaea- and Crenarchaeota-specific primers showed that archaea related to uncultured environmental clones, particularly those of the Crenarchaeota phylum, were present in both carbohydrate- and protein-degrading communities. Five isolates obtained from in situ enrichments or corresponding natural samples of water and sediments represented the bacterial genera Dictyoglomus and Caldanaerobacter as well as new archaea of the Crenarchaeota phylum. Thus, in situ enrichment and consequent isolation showed the diversity of thermophilic prokaryotes competing for biopolymers in microbial communities of terrestrial hot springs.

New short peptaibols from a marine Trichoderma strain

The production of peptaibols by a marine-related Trichoderma longibrachiatum strain was studied using electrospray ionisation multiple-stage ion trap mass spectrometry (ESI-MSn-IT) and gas chromatography/electron impact mass spectrometry (GC/EI-MS). Two major groups of peptaibols were identified, those with long sequences (20 amino acids) and others with short sequences (11 amino acids). This paper describes the methodology used to establish the sequences of short peptaibols in a mixture without previous individual separation. Nine peptaibols were identified. Among them, eight are new, namely as trichobrachin A I-IV (Aib9-Pro10 sequence) and as trichobrachin B I-IV (Val9-Pro10 sequence). Original Pro6-Val7 and Val9-Pro10 sequences have to be noted.

Marine enzymes

Marine enzyme biotechnology can offer novel biocatalysts with properties like high salt tolerance, hyperthermostability, barophilicity, cold adaptivity, and ease in large-scale cultivation. This review deals with the research and development work done on the occurrence, molecular biology, and bioprocessing of marine enzymes during the last decade. Exotic locations have been accessed for the search of novel enzymes. Scientists have isolated proteases and carbohydrases from deep sea hydrothermal vents. Cold active metabolic enzymes from psychrophilic marine microorganisms have received considerable research attention. Marine symbiont microorganisms growing in association with animals and plants were shown to produce enzymes of commercial interest. Microorganisms isolated from sediment and seawater have been the most widely studied, proteases, carbohydrases, and peroxidases being noteworthy. Enzymes from marine animals and plants were primarily studied for their metabolic roles, though proteases and peroxidases have found industrial applications. Novel techniques in molecular biology applied to assess the diversity of chitinases, nitrate, nitrite, ammonia-metabolizing, and pollutant-degrading enzymes are discussed. Genes encoding chitinases, proteases, and carbohydrases from microbial and animal sources have been cloned and characterized. Research on the bioprocessing of marine-derived enzymes, however, has been scanty, focusing mainly on the application of solid-state fermentation to the production of enzymes from microbial sources.

Proteolysis in hyperthermophilic microorganisms

Proteases are found in every cell, where they recognize and break down unneeded or abnormal polypeptides or peptide-based nutrients within or outside the cell. Genome sequence data can be used to compare proteolytic enzyme inventories of different organisms as they relate to physiological needs for protein modification and hydrolysis. In this review, we exploit genome sequence data to compare hyperthermophilic microorganisms from the euryarchaeotal genus Pyrococcus, the crenarchaeote Sulfolobus solfataricus, and the bacterium Thermotoga maritima. An overview of the proteases in these organisms is given based on those proteases that have been characterized and on putative proteases that have been identified from genomic sequences, but have yet to be characterized. The analysis revealed both similarities and differences in the mechanisms utilized for proteolysis by each of these hyperthermophiles and indicated how these mechanisms relate to proteolysis in less thermophilic cells and organisms.

An integrated analysis of the genome of the hyperthermophilic archaeon Pyrococcus abyssi

The hyperthermophilic euryarchaeon Pyrococcus abyssi and the related species Pyrococcus furiosus and Pyrococcus horikoshii, whose genomes have been completely sequenced, are presently used as model organisms in different laboratories to study archaeal DNA replication and gene expression and to develop genetic tools for hyperthermophiles. We have performed an extensive re-annotation of the genome of P. abyssi to obtain an integrated view of its phylogeny, molecular biology and physiology. Many new functions are predicted for both informational and operational proteins. Moreover, several candidate genes have been identified that might encode missing links in key metabolic pathways, some of which have unique biochemical features. The great majority of Pyrococcus proteins are typical archaeal proteins and their phylogenetic pattern agrees with its position near the root of the archaeal tree. However, proteins probably from bacterial origin, including some from mesophilic bacteria, are also present in the P. abyssi genome.

Physiology and continuous culture of the hyperthermophilic deep-sea vent archaeon Pyrococcus abyssi ST549

The deep-sea vent archaeon Pyrococcus abyssi strain ST549 was grown in batch cultures in closed bottles and by continuous culture in a gas-lift bioreactor, both in the presence and in the absence of elemental sulfur. Growth on carbohydrates, proteinaceous substrates and amino acids was investigated. The disaccharides maltose and cellobiose were shown not to be able to enhance growth suggesting that P. abyssi ST549 is unable to use them as carbon sources. By contrast, proteinaceous substrates such as peptone and brain heart infusion were shown to be very good substrates for the growth of P. abyssi ST549 and allowed growth at high steady-state cell densities in continuous culture. Growth on brain heart infusion was shown to require additional nutrients when sulfur was not present in the culture medium. Growth on amino acids only took place in the presence of sulfur. These results indicate that sulfur plays an important role in the metabolism and energetics of P. abyssi ST549.