Petroleum-degrading enzymes: bioremediation and new prospects.

Anthropogenic forces, such as petroleum spills and the incomplete combustion of fossil fuels, have caused an accumulation of petroleum hydrocarbons in the environment. The accumulation of petroleum and its derivatives now constitutes an important environmental problem. Biocatalysis introduces new ways to improve the development of bioremediation strategies. The recent application of molecular tools to biocatalysis may improve bioprospecting research, enzyme yield recovery, and enzyme specificity, thus increasing cost-benefit ratios. Enzymatic remediation is a valuable alternative as it can be easier to work with than whole organisms, especially in extreme environments. Furthermore, the use of free enzymes avoids the release of exotic or genetically modified organisms (GMO) in the environment.

Increased expression of keratinase and other peptidases by Candida parapsilosis mutants.

Keratinases are enzymes of great importance involved in pathogenic processes of some fungi. They also have a widespread ecological role since they are responsible for the degradation and recycling of keratin. On the one hand, studying them furthers our knowledge of pathogenicity mechanisms, which has important implications for human health, and on the other hand, understanding their ecological role in keratin recycling has biotechnological potential. Here, a wild-type keratinolytic Candida parapsilosis strain isolated from a poultry farm was treated with ethyl methanesulfonate in order to generate mutants with increased keratinase activity. Mutants were then cultured on media with keratin extracted from chicken feathers as the sole source of nitrogen and carbon. Approximately 500 mutants were screened and compared with the described keratinolytic wild type. Three strains, H36, I7 and J5, showed enhanced keratinase activity. The wild-type strain produced 80 U/mL of keratinolytic activity, strain H36 produced 110 U/mL, strain I7, 130 U/mL, and strain J5, 140 U/mL. A 70% increase in enzyme activity was recorded for strain J5. Enzymatic activity was evaluated by zymograms with proteic substrates. A peptidase migrating at 100 kDa was detected with keratin, bovine serum albumin and casein. In addition, a peptidase with a molecular mass of 50 kDa was observed with casein in the wild-type strain and in mutants H36 and J5. Gelatinase activity was detected at 60 kDa. A single band of 35 kDa was found in wild-type C. parapsilosis and in mutants with hemoglobin substrate.

Increased expression of keratinase and other peptidases by Candida parapsilosis mutants

Keratinases are enzymes of great importance involved in pathogenic processes of some fungi. They also have a widespread ecological role since they are responsible for the degradation and recycling of keratin. On the one hand, studying them furthers our knowledge of pathogenicity mechanisms, which has important implications for human health, and on the other hand, understanding their ecological role in keratin recycling has biotechnological potential. Here, a wild-type keratinolytic Candida parapsilosis strain isolated from a poultry farm was treated with ethyl methanesulfonate in order to generate mutants with increased keratinase activity. Mutants were then cultured on media with keratin extracted from chicken feathers as the sole source of nitrogen and carbon. Approximately 500 mutants were screened and compared with the described keratinolytic wild type. Three strains, H36, I7 and J5, showed enhanced keratinase activity. The wild-type strain produced 80 U/mL of keratinolytic activity, strain H36 produced 110 U/mL, strain I7, 130 U/mL, and strain J5, 140 U/mL. A 70 percent increase in enzyme activity was recorded for strain J5. Enzymatic activity was evaluated by zymograms with proteic substrates. A peptidase migrating at 100 kDa was detected with keratin, bovine serum albumin and casein. In addition, a peptidase with a molecular mass of 50 kDa was observed with casein in the wild-type strain and in mutants H36 and J5. Gelatinase activity was detected at 60 kDa. A single band of 35 kDa was found in wild-type C. parapsilosis and in mutants with hemoglobin substrate.

Keratinolytic activity of Bacillus subtilis AMR using human hair.

AIMS: To determine the ability of a novel Bacillus subtilis AMR isolated from poultry waste to hydrolyse human hair producing peptidases including keratinases and hair keratin peptides. METHODS AND RESULTS: The Bacillus subtilis AMR was identified using biochemical tests and by analysis of 16S rDNA sequence. The isolate was grown in medium containing human hair as the sole source of carbon and nitrogen. The supplementation of hair medium (HM) with 0.01% yeast extract increased the keratinolytic activity 4.2-fold. B. subtilis AMR presented high keratinase production on the 8th day of fermentation in hair medium (HM) supplemented with 0.01% yeast extract (HMY) at pH 8.0. Keratinase yield was not correlated with increase in biomass. Zymography showed keratin-degrading peptidases migrating at c. 54, 80 and 100 kDa and gelatin-degrading bands at c. 80, 70 63, 54 32 and 15 kDa. Keratinases were optimally active at 50 degrees C and pH 9.0 and was fully inhibited by the serine proteinase inhibitor (PMSF). Scanning electron microscopy showed complete degradation of the hair cuticle after exposure to B. subtilis AMR grown in HMY. MALDI-TOF analysis of culture supernatant containing peptides produced during enzymatic hydrolysis of hair by B. subtilis AMR revealed fragments in a range of 800-2600 Da. CONCLUSIONS: This study showed that B. subtilis AMR was able to hydrolyse human hair producing serine peptidases with keratinase and gelatinase activity as well as hair keratin peptides. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the production and partial characterization of keratinases by a B. subtilis strain grown in a medium containing human hair. These data suggest that peptides obtained from enzymatic hair hydrolysis may be useful for future applications on pharmaceutical and cosmetic formulations.

Proteolytic expression in Blastocrithidia culicis: influence of the endosymbiont and similarities with virulence factors of pathogenic trypanosomatids.

Blastocrithidia culicis is an insect trypanosomatid that presents bacterial endosymbionts. The cell-associated and secreted proteinases of the endosymbiont-bearing and aposymbiotic strains were compared through the incorporation of proteinaceous substrates into sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Few qualitative changes could be detected in the proteolytic zymograms in the 2 strains studied when gelatin, casein, haemoglobin or bovine serum albumin (BSA) were tested. However, the level of proteolytic activities was significantly higher in the aposymbiotic strain. Some of the B. culicis proteins reacted in Western blots with antibodies raised against gp63, a zinc-metalloproteinase, and cruzipain, a cysteinyl-proteinase, which are virulence factors of the human pathogenic trypanosomatids, Leishmania spp. and Trypanosoma cruzi, respectively. The anti-cross-reacting determinant (CRD) antibody recognized 2 polypeptides (50 and 58 kDa) in the spent culture media and in the supernatant from glycosylphosphatidylinositol-phospholipase C (GPI-PLC)-treated cells, suggesting that these proteins are GPI-anchored to the plasma membrane. In addition, the anti-gp63 reacted with the 50 kDa protein. The identification of protein homologues in trypanosomatids with distinct life-cycles may help to determine the importance of proteinases in trypanosomatids.

Differential expression of proteolytic enzymes in endosymbiont-harboring Crithidia species.

Crithidia oncopelti, Crithidia deanei and Crithidia desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Gelatin-SDS-PAGE analysis was used to characterize cell-associated and extracellular proteinases in these organisms. Our survey indicates that the proteolytic profiles of C. deanei and C. desouzai are identical; that C. oncopelti displays a distinct zymogram; and that species naturally lacking endosymbionts have a more complex extracellular proteolytic activity, which illustrates the heterogeneity of this genus. This is the first report on the presence of cysteine proteinases in the culture supernatant of monoxenic trypanosomatids, and by the use of wild and aposymbiotic strains from C. deanei we also demonstrated that the prokaryote endosymbiont somehow alters quantitatively the expression of extracellular proteinases in this trypanosomatid.

Crithidia guilhermei: purification and partial characterization of a 62-kDa extracellular metalloproteinase.

An extracellular metalloproteinase from Crithidia guilhermei, a monoxenic trypanosomatid of insects, was purified 11-fold by ammonium sulfate precipitation, gel filtration on a Shinpack Diol-150 column, and anion-exchange chromatography in a MONO Q column, both using the HPLC system. The proteinase appeared as a single band with an apparent molecular mass of 62 kDa in SDS-PAGE, under reducing conditions, and was optimally active at 37 degrees C and pH 6.0. The enzyme showed 62% residual activity at 50 degrees C for 30 min. The proteinase was completely inhibited by 1, 10-phenanthroline, indicating that the enzyme belongs to the metalloproteinase class. This is the first report of the purification of an extracellular metalloproteinase from the Crithidia species. The possible role of this enzyme in the digestive tract of the insect host is discussed.

Surface component characterization as taxonomic tools for Phytomonas spp identification.

The genus Phytomonas arbitrarily includes all protozoa of the family Trypanosomatidae isolated from plants, but its differentiation is a complex task. The phase separation technique using Triton X-114 was used to analyze hydrophobic and hydrophilic surface proteins in ten strains of Phytomonas isolated from various fruits. The iodination of surface proteins by the Iodo-Gen method was also used for Phytomonas isolates from tomatoes, corn and annatto, Herpetomonas samuelpessoai and Crithidia fasciculata. The distribution of protein-bound radioactivity in acrylamide gels was determined by autoradiograms and showed the presence of protein bands of 36-68 kDa in all strains of Phytomonas: there were two major bands at 88 kDa and 94 kDa, with minor bands at 36 kDa and 142 kDa in H. samuelpessoai; and there were three bands at 74, 86 and 94 kDa, with minor bands at 23 kDa and 105 kDa in C. fasciculata. The results demonstrated that samples of plant parasites can be clearly differentiated from H. samuelpessoai and C. fasciculata. These plant parasites were also submitted to polysaccharide analysis by gas-liquid chromatography of the corresponding alditol acetate. Arabinose, galactose, glucose and mannose, were the major monosaccharides found, while fucose, rhamnose and xylose were found in smaller amounts. The results of all these methods indicated that, after extension to a wider range of trypanosomatid strains, they may be useful in Phytomonas taxonomy.

Extracellular serine-proteinases isolated from Streptomyces alboniger: partial characterization and effect of aprotinin on cellular structure.

Streptomyces alboniger ATCC 12461 grown in brain heart infusion (BHI) medium produced two extracellular serine-proteinases, denoted SP I and SP II, which were purified by ammonium sulfate precipitation and aprotinin-agarose affinity chromatography. SP I was purified 88,9-fold and SP II 66,7- fold, with 33.4% and 10.4% yield, respectively. The optimum pH for the proteinases activity, using a-N-p-tosyl-L-arginine-methyl ester (TAME) as substrate, was 9-10 and the optimum temperature was 37 degrees C. The proteolytic activity of SP I and SP II was inhibited by aprotinin and SP I was partially inhibited by leupeptin, both serine-proteinase inhibitors. S. alboniger growth in BHI-liquid medium decreased when 5 mg/ml, 10 mg/ml of aprotinin was used, being completely inhibited with 20 mg/ml and 40 mg/ml. At the ultrastructural level, aprotinin-treated S. alboniger cells showed swelling of the bacterial body and condensation of the genetic material, probably related to the inhibition of its growth.

Purification and partial characterization of an extracellular serine-proteinase of Streptomyces cyaneus isolated from Brazilian cerrado soil.

Streptomyces cyaneus, a micro-organism isolated from Brazilian cerrado soil, produces an extracellular proteinase (SCP), which was purified 22-fold to homogeneity from culture supernatant fluid, using a single aprotinin-agarose affinity chromatography step. It is produced at a level corresponding to approximately 15% of total protein, but its physiological function has yet to be determined. The molecular mass of this S. cyaneus proteinase was estimated to be 120 kDa by gel filtration high performance liquid chromatography, and it migrates by SDS-PAGE as a single band of 30 kDa. It was optimally active at 25 degrees C and pH 9.0, and was fully inhibited by the serine-proteinase inhibitors PMSF and TPCK. A Km value of 1. 86 x 10-5 mmol l-1, and Vmax of 2.0 x 10-2 mmol l-1 (Abs247 nm microg-1 min-1), were calculated for alpha-N-p-tosyl-L-arginine-methyl ester (TAME) as substrate.

Structural studies on the polar glycoinositol phospholipids of Trypanosoma (Schizotrypanum) dionisii from bats.

The polar glycoinositol phospholipids (GIPLs) of a Trypanosoma species that belongs to the Schizotrypanum subgenus were purified by reversed-phase and normal-phase liquid chromatography and analysed by negative-ion mode electrospray-mass spectrometry (ES-MS). The phosphatidylinositol moieties were released by nitrous acid deamination and identified as ceramide- and alkylacylglycerol-containing species. The structures of the GIPLs were determined using chemical treatments, sequential exoglycosidase digestions and positive-ion mode ES-MS-MS. All of the GIPLs were based on the same Man alpha1-2Man alpha1-2Man alpha1-6Man alpha1-4(NH2-CH2CH2-HPO3-)GlcN-PI core with single terminal Galf residue substitutions either on the terminal nonreducing Man or on the second alphaMan residue from the inositol and with either ethanolamine phosphate or 2-aminoethylphosphonate on the third alphaMan residue from the inositol. The T. (S.) dionisii GIPLs are compared with those of T. (S.) cruzi, a closely related species of the Schizotrypanum subgenus.

Trypanosoma cruzi-cardiomyocytes: new contributions regarding a better understanding of this interaction.

The present paper summarizes new approaches regarding the progress done to the understanding of the interaction of Trypanosoma cruzi-cardiomyocytes. Mannose receptors localized at the surface of heart muscle cell are involved in binding and uptake of the parasite. One of the most striking events in the parasite-heart muscle cells interaction is the disruption of the actin cytoskeleton. We have investigated the regulation of the actin mRNA during the cytopathology induced in myocardial cells by the parasite. T. cruzi invasion increases calcium resting levels in cardiomyocytes. We have previously shown that Ca2+ ATPase of the sarcoplasmic reticulum (SERCA) is involved in the invasion of T. cruzi in cardiomyocytes. Treating the cells with thapsigargin, a drug that binds to all SERCA ATPases and causes depletion of intracellular calcium stores, we found a 75% inhibition in the T. cruzi-cardiomyocytes invasion.

Heart muscle cells share common neutral glycosphingolipids with Trypanosoma cruzi.

Neutral glycosphingolipids were isolated from mouse heart muscle cells and their structures were analyzed. The molecular compositions of these glycosphingolipids were examined using column chromatography, HPTLC, GC-MS and fast atom bombardment-mass spectrometry (FAB-MS). Monohexosylceramides are a mixture of glucosyl- and galactosylceramides in a ratio of 1:1, sphingosine as the long chain base and as fatty acyl groups mainly C16, C18 saturated and C22 and C24 hydroxy fatty acids. Dihexosylceramide, identified as lactosylceramide contains C18 sphingosine and C18, C20 and C22 were the major fatty acids. No evidence for the occurrence of hydroxylated fatty acids in this glycolipid could be obtained from the GC-MS data. Our results clearly demonstrated that Trypanosoma cruzi and heart muscle cells have similar glycosphingolipid structures. In addition, heart muscle cells neutral glycosphingolipids have been shown to be immunoreactive. Antibodies reactive with each of the immunogenic glycolipids from heart cells or T. cruzi epimastigotes were present in the sera of human patients with Chagas disease as detected by ELISA. These cross-reactive antigens could be involved in the Chagasic autoimmunity.

Monohexosylceramides of Trypanosoma dionisii.

A detailed knowledge of the primary structure of neutral glycosphingolipids isolated and purified from Trypanosoma dionisii has been elucidated using a combination of techniques--as column chromatography, HPTLC and GC-MS together with fast atom bombardment spectrometry. The ceramide monohexoside fraction (CMH) contained both glucosyl- and galactosylceramides in a ratio of 1:1, sphingosine and as fatty acyl groups mainly C-24 saturated and 2-hydroxy fatty acids. A close similarity between Trypanosoma cruzi and T. dionisii monohexosylceramides was reported.

Detection of extracellular proteases from microorganisms on agar plates.

We present herein an improved assay for detecting the presence of extracellular proteases from microorganisms on agar plates. Using different substrates (gelatin, BSA, hemoglobin) incorporated into the agar and varying the culture medium composition, we were able to detect proteolytic activities from Pseudomonas aeruginosa, Micrococcus luteus and Serratia marcescens as well as the influence that these components displayed in the expression of these enzymes. For all microorganisms tested we found that in agar-BHI or yeast extract medium containing gelatin the sensitivity of proteinase detection was considerably greater than in BSA-agar or hemoglobin-agar. However, when BSA or hemoglobin were added to the culture medium, there was an increase in growth along with a marked reduction in the amount of proteinase production. In the case of M. luteus the incorporation of glycerol in BHI or yeast extract gelatin-agar induced protease liberation. Our results indicate that the technique described here is of value for detecting extracellular proteases directly in the culture medium, by means of a qualitative assay, simple, inexpensive, straight forward method to assess the presence of the proteolytic activity of a given microorganism colony with great freedom in substrate selection.

Ubiquity of cysteine- and metalloproteinase activities in a wide range of trypanosomatids.

We have analysed the proteinase profiles of 11 species from 7 different genera of trypanosomatids by in situ detection of enzyme activities on SDS-PAGE gels containing co-polymerized gelatin as substrate, and the use of specific proteinase inhibitors. Our survey indicates that while cysteine- and metalloproteinases are distributed ubiquitously among trypanosomatids, there are marked differences between the enzyme profiles from the monogenetic (Crithidia, Herpetomonas, Leptomonas) and digenetic (Trypanosoma, Endotrypanum, Phytomonas, Leishmania) species. The detected metalloproteinase activities, ranging in size from 50-100 kDa, partitioned into the detergent-phase after Triton X-114 extraction, while most of cysteine proteinases, of three distinct molecular mass ranges (30-50 kDa, 80-100 kDa and 116-205 kDa), partitioned into the aqueous phase. Thus, within this group of organisms, the metalloproteinase activities seem to be predominantly membrane-associated proteins. We also show that the plant parasites of the genus Phytomonas exhibit a distinctive cysteine proteinase profile that might be exploited further as a criterion for taxonomy of the genus.

Use of glycoconjugates for trypanosomatid taxonomy.

Glycoconjugates from five trypanosomatid genera--Crithidia, Herpetomonas, Endotrypanum, Leishmania, and Trypanosoma--were extracted with Triton X-114 and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by periodic acid-Schiff staining. Most of the glycoconjugates were detected in the hydrophobic phase, indicating the presence of anchored glycoconjugates. All the trypanosomatids expressed a glycoconjugate with a low molecular weight (below 20 kDa) in this phase. In each species, however, a characteristic and specific pattern of glycoconjugates was also observed in both phases. In the hydrophobic phase: 14-29 kDa glycoconjugates in C. guilhermei; 24-70 kDa in C. fasciculata, C. luciliae, E. schaudinni, and T. cruzi Y and G strains; 45-66 kDa in C. oncopelti and H. samuelpessoai; above 36 kDa in T. dionisii; 20-24 kDa, 36-45 kDa, and 70 kDa in L. tarentolae and T. mega. In the hydrophilic phase, typical glycoproteins were observed in some trypanosomatids: 60 kDa in T. mega and T. cruzi Y strain; 70 kDa in H. samuelpessoai; 66 kDa in C. oncopelti; 20-70 kDa in C. luciliae. These findings suggest that Triton X-114-extracted glycoconjugates could be useful markers for trypanosomatid taxonomy.

Characterization of proteinases in trypanosomatids.

Proteinases are important factors in the pathogenicity of many parasitic diseases. In this study, the proteolytic activities of 10 trypanosomatids from five different genera (Crithidia, Phytomonas, Endotrypanum, Trypanosoma and Leishmania) were determined by SDS-PAGE containing copolymerized gelatin as substrate. In almost all species we could detect two proteolytic classes, cysteine- and metalloproteinases, based on the inhibition of their activities by E-64 and 1,10-phenanthroline, respectively. In all cases, the metalloproteinase activities did not change over a broad pH range (from 5.5 to 10). E. schaudinni, T. mega, T. dionisii, C. luciliae, C. fasciculata, C. oncopelti and C. guilhermei expressed one or two metalloproteinases of 45-66 kDa, whereas in P. serpens and P. hyssopifolia a double band of this endopeptidase was detected at 94 kDa. In contrast, no metalloproteinase activity was observed in L. tarentolae. The optimal pH for the cysteine-proteinase activities was acidic (about 5.5). In E. schaudinni, T. mega and in Crithidia sp., these proteinases had an apparent molecular weight of 66-94 kDa, while L. tarentolae expressed a broad band from 29 to 45 kDa. In Phytomonas sp., this class of endopeptidase showed a unique feature, in that major cysteine-proteinases were found at 29-66 kDa, but multiple, low-activity bands were detected from 116 to 200 kDa. The most striking characteristic, however, was the very intense cysteine-proteinase activity expressed by T. dionisii (29-66 kDa). We conclude that these differences in the proteolytic profiles could be useful markers to characterize and compare trypanosomatids.

Glycolipid and protein profiles in trypanosomatids.

A comparative study of glycolipid and protein composition in Trypanosoma cruzi and non-pathogenic trypanosomatids was carried out using Triton X-114 extraction. Protein profiles were analysed by polyacrylamide gel electrophoresis in sodium dodecyl sulphate (SDS-PAGE), and glycolipids were detected using high-performance thin-layer chromatography (HPTLC). Hydrophilic protein profiles were similar in non-pathogenic protozoa. Endotrypanum schaudinni, Crithidia luciliae and T. mega showed five characteristic protein bands ranging between 30 and 66 kDa. In the hydrophobic phase, a band of 50 kDa was present only in T. mega. Strain-specific protein distribution was detected in T. cruzi clone Dm28c and T. cruzi G and Y strains; clone Dm28c had five typical hydrophilic proteins at between 24 and 45 kDa, the G strain had two bands at 45 kDa in the hydrophilic phase and the Y strain had a major protein band at 24 kDa in both phases. T. dionisii and T. cruzi clone Dm28c showed a characteristic distribution of three hydrophilic proteins of approx. 45 kDa. Qualitative analysis of glycolipid composition showed that the T. cruzi strains and Dm28c clone and T. dionisii had four orcinol-positive spots, whereas in the other non-pathogenic trypanosomatids only three glycolipids were detected.