A novel small antifungal peptide from Bacillus strain B-TL2 isolated from tobacco stems

Biocontrol Methods in Avoidance and Downsizing of Mycotoxin Contamination of Food Crops

By increasing the resistance of seeds against abiotic and biotic stress, the possibility of cereal mold contamination and hence the occurrence of secondary mold metabolites mycotoxins decreases. The use of biological methods of seed treatment represents a complementary strategy, which can be implemented as an environmental-friendlier approach to increase the agricultural sustainability. Whereas the use of resistant cultivars helps to reduce mold growth and mycotoxin contamination at the very beginning of the production chain, biological detoxification of cereals provides additional weapons against fungal pathogens in the later stage. Most efficient techniques can be selected and combined on an industrial scale to reduce losses and boost crop yields and agriculture sustainability, increasing at the same time food and feed safety. This paper strives to emphasize the possibility of implementation of biocontrol methods in the production of resistant seeds and the prevention and reduction in cereal mycotoxin contamination.

Recent Updates on Antifungal Peptides

The current trend of increment in the frequency of antifungal resistance has brought research into an era where new antifungal compounds with novel mechanisms of action are required. Natural antimicrobial peptides, which are ubiquitous components of innate immunity, represent their candidature for novel antifungal peptides. Various antifungal peptides have been isolated from different species ranging from small marine organisms to insects and from various other living species. Based on these peptides, various mimetics of antifungal peptides have also been synthesized using non-natural amino acids. Utilization of these antifungal peptides is somehow limited due to their toxic and unstable nature. This review discusses recent updates and future directions of antifungal peptides, for taking them to the shelf from the bench.

Antagonistic Activities of Novel Peptides from Bacillus amyloliquefaciens PT14 against Fusarium solani and Fusarium oxysporum

Bacillus species have recently drawn attention due to their potential use in the biological control of fungal diseases. This paper reports on the antifungal activity of novel peptides isolated from Bacillus amyloliquefaciens PT14. Reverse-phase high-performance liquid chromatography revealed that B. amyloliquefaciens PT14 produces five peptides (PT14-1, -2, -3, -4a, and -4b) that exhibit antifungal activity but are inactive against bacterial strains. In particular, PT14-3 and PT14-4a showed broad-spectrum antifungal activity against Fusarium solani and Fusarium oxysporum. The PT14-4a N-terminal amino acid sequence was identified through Edman degradation, and a BLAST homology analysis showed it not to be identical to any other protein or peptide. PT14-4a displayed strong fungicidal activity with minimal inhibitory concentrations of 3.12 mg/L (F. solani) and 6.25 mg/L (F. oxysporum), inducing severe morphological deformation in the conidia and hyphae. On the other hand, PT14-4a had no detectable hemolytic activity. This suggests PT14-4a has the potential to serve as an antifungal agent in clinical therapeutic and crop-protection applications.

Antiangiogenic activity of the lipophilic antimicrobial peptides from an endophytic bacterial strain isolated from red pepper leaf

The induction of angiogenesis is a crucial step in tumor progression, and therefore, efficient inhibition of angiogenesis is considered a powerful strategy for the treatment of cancer. In the present study, we report that the lipophilic antimicrobial peptides from EML-CAP3, a new endophytic bacterial strain isolated from red pepper leaf (Capsicum annuum L.), exhibit potent antiangiogenic activity both in vitro and in vivo. The newly obtained antimicrobial peptides effectively inhibited the proliferation of human umbilical vein endothelial cells at subtoxic doses. Furthermore, the peptides suppressed the in vitro characteristics of angiogenesis such as endothelial cell invasion and tube formation stimulated by vascular endothelial growth factor, as well as neovascularization of the chorioallantoic membrane of growing chick embryos in vivo without showing cytotoxicity. Notably, the angiostatic peptides blocked tumor cell-induced angiogenesis by suppressing the expression levels of hypoxia-inducible factor-1α and its target gene, vascular endothelial growth factor (VEGF). To our knowledge, our findings demonstrate for the first time that the antimicrobial peptides from EML-CAP3 possess antiangiogenic potential and may thus be used for the treatment of hypervascularized tumors.

The potential hazards of Aspergillus sp. in foods and feeds, and the role of biological treatment: a review

The contamination of food and feed by Aspergillus has become a global issue with a significant worldwide economic impact. The growth of Aspergillus is unfavourable to the development of food and feed industries, where the problems happen mostly due to the presence of mycotoxins, which is a toxic metabolite secreted by most Aspergillus groups. Moreover, fungi can produce spores that cause diseases, such as allergies and asthma, especially to human beings. High temperature, high moisture, retarded crops, and poor food storage conditions encourage the growth of mold, as well as the development of mycotoxins. A variety of chemical, biological, and physical strategies have been developed to control the production of mycotoxins. A biological approach, using a mixed culture comprised of Saccharomyces cerevisiae and Lactobacillus rhamnosus resulted in the inhibition of the growth of fungi when inoculated into fermented food. The results reveal that the mixed culture has a higher potential (37.08%) to inhibit the growth of Aspergillus flavus (producer of Aflatoxin) compared to either single culture, L. rhamnosus NRRL B-442 and S. cerevisiae, which inhibit the growth by 63.07% and 64.24%, respectively.

Polar characterization of antifungal peptides from APD2 Database

The increase in the number of pathogens due to fungi that are tolerant to therapies does not grow at the same speed than the advance on new antifungal drugs. In this sense, it is imperative to find anti-fungi peptides that are not detrimental to mammalian cells and have an effective toxicity to fungi. In this work, we use a method called polarity index, to identify anti-fungi peptides with an efficiency of 70 %. This method already published, initially identified selective antibacterial peptides from APD2 Database, and was characterized by developing a comprehensive analysis of the polar dynamics of a peptide from its linear sequence. Discriminating tests showed that in addition to being efficient in this identification, it was also good at rejecting other classifications of peptides found in that same database.

Purification and characterization of a novel antifungal protein secreted by Penicillium chrysogenum from an Arctic sediment

A fungal strain, Penicillium chrysogenum A096, was isolated from an Arctic sediment sample. Its culture supernatant inhibited mycelial growth of some plant pathogenic fungi. After saturation of P. chrysogenum A096 culture supernatant with ammonium sulfate and ion exchange chromatography, a novel antifungal protein (Pc-Arctin) was purified and identified by matrix assisted laser desorption ionization-time of flight-time of flight-mass spectrometry (MALDI-TOF-TOF-MS). The gene encoding for Pc-Arctin consisting of 195 nucleotides was cloned from P. chrysogenum A096 to confirm the mass spectrometry result. Pc-Arctin displays antifungal activity against Paecilomyces variotii, Alternaria longipes, and Trichoderma viride at minimum inhibitory concentrations (MIC) of 24, 48, and 192 ng/disc, respectively. Pc-Arctin was most sensitive to proteinase K and then to trypsin but insensitive to papain. Pc-Arctin possesses high thermostability and cannot be antagonized by common surfactants, except for sodium dodecyl sulfate (SDS). Divalent ions, such as Mn(2+), Mg(2+), and Zn(2+), inhibited the antifungal activity of Pc-Arctin. Hemagglutination assays showed that Pc-Arctin had no hemagglutinating or hemolytic activity against red blood cells (RBC) from rabbits, rats, and guinea pigs. Therefore, Pc-Arctin from Arctic P. chrysogenum may represent a novel antifungal protein with potential for application in controlling plant pathogenic fungal infection.

Tostadin, a novel antibacterial peptide from an antagonistic microorganism Brevibacillus brevis XDH

A novel small antibacterial peptide was obtained from the liquid culture of Brevibacillus brevis XDH, which is a broad-spectrum antagonistic bacterium isolated from the soil of Mountain Tai, China. This peptide was purified from the fermentation medium of strain XDH via ammonium sulfate precipitation, cation exchange chromatography, and reversed-phase high-performance liquid chromatography (HPLC), successively. The structure of the active linear peptide was elucidated using mass spectra (MS) and nuclear magnetic resonance (NMR) analyses that consisted of nine amino acids. This peptide was easily soluble in water, thermally stable and strongly inhibited the growth of Escherichia coli and Staphylococcus aureus in vitro. The present data support the identification of a novel antibacterial peptide, which was named Tostadin.

Purification and characterization of a novel antimicrobial peptide from Brevibacillus laterosporus strain A60

A novel antimicrobial peptide, with molecular mass of 1602.0469Da, produced by Brevibacillus laterosporus strain A60 was isolated and purified from the soil of mango plants. The purification procedure consisted of ammonium sulfate precipitation, cation exchange chromatography on an HiTrap SP HP column, thin layer chromatography and High Performance Liquid Chromatography (HPLC) on C18 reversed-phase column. After the four isolation procedures, one peptide with antimicrobial activity was obtained and named BL-A60. The determination of the complete amino acid sequences of this peptide showed that it contains eleven amino acid residues, L-Y-K-L-V-K-V-V-L-N-M, and a choline connected to the N-terminal and a tenuazonic acid modified of the C-terminal. This peptide shows relatively low identification to other antimicrobial peptides from bacteria. Purified BL-A60 showed high pH and thermal stability and a strong inhibition of different stages of the life cycle of Phytophthora capsici, including mycelial growth, sporangia formation and cystospore germination, with EC(50) values of 7.89, 0.60 and 21.96 μg ml(-1), respectively.

Peptide antibiotics: an alternative and effective antimicrobial strategy to circumvent fungal infections

Mycosis, caused by both filamentous fungi and pathogenic yeasts is a major concern nowadays especially in the immunocompromised patient population. The emergence of pathogenic fungi resistant to current therapies in the last few decades has intensified the search for new antifungals like cationic peptides, which are the key components of innate defense mechanism. The review provides an inventory of different peptides from a diverse array of organisms from bacteria to mammals with proven antifungal activity, their therapeutic options and also about those which are in various stages of preclinical development. Literature, on the total and semi-synthetic variants of the parent peptides that exhibit an improved antifungal activity is also reviewed.

First isolation of a novel thermostable antifungal peptide secreted by Aspergillus clavatus

A novel antifungal peptide produced by an indigenous fungal strain (VR) of Aspergillus clavatus was purified. The antifungal peptide was enriched in the supernatant after heat treatment at 70 degrees C. The thermostable character was exploited in the first purification step, as purified peptide was obtained after ultrafiltration and reverse phase-HPLC on C18 column application. The purified peptide named "AcAFP" for A. clavatus antifungal peptide, has molecular mass of 5773Da determined by MALDI-ToF spectrometry. The N-terminal sequence showed a notable identity to the limited family of antifungal peptides produced by ascomycetes fungi. The AcAFP activity remains intact even after heat treatment at 100 degrees C for 1h confirming its thermostability. It exhibits a strong inhibitory activity against mycelial growth of several serious human and plant pathogenic fungi: Fusariuym oxysporum, Fusarium solani, Aspergillus niger, Botrytis cinerea, Alternaria solani, whereas AcAFP did not affect yeast and bacterial growth.