Biology subjects

Silva Junior, P. I.

Publications and source records attributed to Silva Junior, P. I..

5 recordsLinked to original sources

bioRxiv2022

TsTX-kappa beta (Ts8), a neurotoxin from the venom of the scorpion Tityus serrulatus: antimicrobial and hemolytic activity.

Increase of infections caused by microorganisms resistant to conventional antibiotics is a health problem in Brazil and worldwide. The search for new molecules capable of inhibiting the growth of pathogens is a challenge for researchers, who find in venoms a rich source of biomolecules, including antimicrobial peptides (AMPs). The Brazilian scorpion, Tityus serrulatus, is one of the species that cause serious accidents; its venom is rich in neurotoxins that have been well characterized, highlighting their activities on channels (especially sodium and potassium). In this study we identifified and characterized one AMPs in T. serrulatus venom. After milking, the venom was fractioned by high performance liquid chromatography and the fractions were tested by liquid growth inhibition assay, the minimum inhibitory concentration (MIC) against Escherichia coli, Micrococcus luteus, Candida albicans and Aspergillus niger. The fraction identified with antimicrobial activity was analyzed by electrophoresis and mass spectrometry and this AMP (with molecular mass 6.882 kDa) has a similar amino acid sequence to TsTX-{kappa} beta, a neurotoxin that acts on ion channels. The TsTX-{kappa} beta in this study was identified by de novo sequencing. This peptide showed activity against all microorganisms tested. At high concentrations, this peptide, showed hemolytic activity against human erythrocytes. This is a new function described for this peptide, the identification of antimicrobial activity in a neurotoxin already known. Key ContributionMultifunction: antimicrobial and hemolytic activity associated to TsTX-{kappa} beta, a neurotoxin that acts on potassium channels.

microbiology↗

bioRxiv2022

How a tarantula can help treat infections: Avicularia juruensis theraphotoxins that also act as antimicrobials.

Short abstractConsidering that there are still many species little-studied, this work aimed to analyze the venom of the spider Avicularia juruensis searching for antimicrobial peptides. Using reverse-phase high-performance liquid chromatography, microbial growth inhibition assay, transcriptomics, and proteomics approaches we identified three antimicrobial peptides: Avilin, Juruin_2, and Juruenine. All of them showed similarities with neurotoxins that act on ion channels and, probably, they have the ICK motif. The study of animal venoms is of great importance to carry out the characterization of unknown components and that may have a biotechnological application, in special venoms from spiders that are from less studied families. Spiders are the most successful group of venomous animals, comprising more than 50,350 species distributed in all terrestrial habitats. One strategy that facility their broad distribution is the production of elaborate venoms, which are composed of inorganic salts, organic molecules with low molecular mass, free amino acids, small polypeptides, linear peptides, nucleotides, disulfide-rich peptides, enzymes, and high molecular mass proteins. Considering that there are still many species little-studied, this work aimed to analyze the venom of the mygalomorph spider Avicularia juruensis searching for new antimicrobial peptides. Using reverse-phase high-performance liquid chromatography, microbial growth inhibition assay, transcriptomics, and proteomics approaches we identified three antimicrobial peptides that were named Avilin, Juruin_2, and Juruenine. All of them showed similarities with neurotoxins that act on ion channels and, probably, they have the ICK motif in their structure. The ICK fold seems to be conserved in several venomous animal lineages and presents elevated functional diversity, as well as gives stability to the toxins. The study of animal venoms is of great importance to carry out the characterization of unknown components and that may have a biotechnological application (like the antimicrobial peptides), in special venoms from spiders that are from less studied families.

microbiology↗

bioRxiv2022

Doderlin: Isolation and Characterization of a Broad-Spectrum Antimicrobial Peptide from Lactobacillus acidophilus

Lactobacillus acidophilus are Gram-positive bacteria distributed in diverse environments, and as being a component of the normal microbiota of gastrointestinal and urogenital tract, being relevant to humans. Classified as lactic acid bacteria, due to the pro-duction of lactic acid, Lactobacillus can also produce antimicrobial peptides (AMPs), which is a compound synthesized by all forms of life aiming for protecting themselves from threats and to increase their competitivity to survive in a specific environment. AMPs are molecules capable of inhibiting the growth of microorganisms and, due to the indiscriminate use of conventional antibiotics and the emergence of multi-resistant bacteria, they have become an alternative, not only for treating multi-resistant infections, but also for probiotic product confection and food conservation. Considering the rampant rise of resistance, the present study aimed to isolate and characterize antimicrobial peptides from Lactobacillus acidophilus extracts. Samples were obtained from Lactobacillus acid extract supernatant which was pre-fractionated on disposable cartridges, followed by a high-performance liquid chromatography (HPLC). The collected fractions were evaluated in a liquid growth inhibition assay where eight fractions antimicrobial activity were obtained. One of them was selected for further characterization by mass spectrometry (MS), due to its antimicrobial activity against Candida albicans and conclusive results in mass spectrometry analysis. This molecule was identified as a peptide having a molecular mass of 1788.01 Da, peptide sequence NEPTHLLKAFSKAGFQ, and named Doderlin. Interestingly, antimicrobial molecules isolated from L. acidophilus have already been described previously, but few reports in the literature describe an AMP effective against C. albicans as reported here. The results obtained suggest that this newly discovered molecule have a biological property with potential to be applied in pharmaceutical and food companies in the fight against contamination and/or for treating infections caused by microorganisms. IMPORTANCEDoderlin, this newly discovered molecule have a biological property with potential to be applied in pharmaceutical and food companies in the fight against contamination and/or for treating infections caused by microorganisms.

microbiology↗

bioRxiv2021

Ovipin: a chicken eggs antibiotic agent

The intensive and indiscriminate use of antibiotic has increased cases of microorganisms resistance and becoming a worldwide public health problem. In the last years, from natural sources such as hens egg, have received special attention in the discovery of new bioactive compounds. This study aims to identify and characterize a new peptide from chicken egg of Gallus gallus domesticus. The chicken egg was subjected the extraction acid, the supernatant was prefractionated in Sep- Pak column and fractionated peptide by reverse-phase high-performance liquid chromatography (RP-HPLC). The antimicrobial activity of the fractions were evaluated through liquid growth inhibition assays. The molecular weight and amino acid sequence was determined by mass spectrometry (MS/MS), the characaterization performed by bioinformatics analysis with Peaks(R) tool and comparision with the NCBI and UniProt-SwisProt database. The physicochemical parameters of the samples were evaluated with online programs. One fraction named Ovipin peptide, showed antimicrobial activity against Gram-positive bacteria (Micrococcus luteus - MIC 1.94 {micro}M) and Filamentous fungus (Aspergillus niger - MIC 31.01 {micro}M). The minimum inhibitory concentration against Cryptococcus neoformans VNI (WM 148) Yeast was 15.51 {micro}M, this microorganism an opportunistic yeast and mainly binds in immunosuppressed or immunocompromissed people. Ovipin is a hydrophoic peptide and not cause significant hemolytic effect against human erythrocytes. Ovipin primary sequence is YVSPVAIVKGLNIPL and a molecular weight of 1,581.94 Da. Ovipin shows 100% and 93.3%, respectively, sequence similarity with the fragments Apolipoprotein B of Gallus gallus and Apolipoprotein B of five others species of Aves. Our data suggest that Ovipin peptide could be a potential therapeutic candidate to be used an alternative against infections developed by resistant microorganisms, mainly in the fight against Cryptococcus neoformans opportunistic yeast.

microbiology↗

bioRxiv2021

Limacus flavus yellow slug: bioactive molecules in the mucus

BackgroundSnails and slugs were used as a treatment for many health problems therefore ancient times. Since the antimicrobial resistance became a major global thread, antimicrobial peptides have been considered as a potential source for development of new drugs, especially for drug-resistant bacteria. Nowadays reports confirm that the mucous secretions have antimicrobial, antiviral and antifungal properties. MethodsThe present study has the objective to characterize and evaluate antimicrobial peptides of Limacus flavus mucus. The mucus was obtained by thermal shock and submitted to RP-HPLC. Fractions were used to perform the antimicrobial activity and hemolytic assays, electrophoresis (SDS-Page Gel) and submitted to mass spectrometry (LC-MS / MS). Identification and characterization was performed by PeaksX+ software. The physicochemical parameters were evaluated with bioinformatics tools, which predicted water solubility, iso-electric point, charge net and its primary structure. ResultsThree fractions were isolated from the mucus of L. flavus and presented antifungal and antibacterial activity. The mucus showed greater inhibition for filamentous fungi (Aspergillus niger), yeast (Cryptococcus neoformans), Gram positive bacteria (Bacillus subtilis, Micrococcus luteus) and Gram negative bacteria (Enterobacter cloacae). These fractions also did not show hemolytic activity for human blood cells (erythrocytes). Fractions sequences were identified and presents Mw <3kDa, WLGH, DLQW, YLRW, respectively. ConclusionThis study revealed three antimicrobial peptides of L. flavus mucus with a wide range of antimicrobial activity and its physic-chemical characterization.

microbiology↗