Assessment of Feather Hydrolysate from Thermophilic Actinomycetes for Soil Amendment and Biological control Application, Int

ABSTRACT: Protein-rich hydrolysate from feather waste was obtained using a mixed culture of selected thermophilic actinomycete strains, and was tested for possible application as soil amendment and biological control agent. For this purpose, a 4 months laboratory experiment was carried out using two types of urban soils (Sofia, Bulgaria): native park soil and anthropogenic soil. The effect of the obtained hydrolysate on some soil parameters (pH, some enzyme activities and microbial activity), seed germination and ryegrass growth, and activity against some plant pathogenic fungi was studied. The results demonstrated that soil enrichment with the organic solution in low concentrations exerted a positive effect on soil urease and microbial activity, seed germination and ryegrass growth, and this trend was better expressed in the anthropogenic soils. Feather hydrolysate showed good activity against plant pathogenic fungi Fusarium solani, Fusarium oxysporum, Mucor sp. and Aspergillus niger. Produced antifungal compounds were isolated and partially characterized as amphiphilic peptides. To the best of our knowledge, antifungal peptides produced by Thermoactinomyces sp. have not been reported. Therefore, the feather hydrolysate obtained by means of the mixed culture of Thermoactinomyces strains has potential to be used as alternative organic amendment for restoration of contaminated soils and for accelerating ryegrass growth. It could successfully used also for as biocontrol agent applicable to crop plant soil

Rhamnolipids: diversity of structures, microbial origins and roles

Rhamnolipids are glycolipidic biosurfactants produced by various bacterial species. They were initially found as exoproducts of the opportunistic pathogen Pseudomonas aeruginosa and described as a mixture of four congeners: α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-Rha-C10-C10), α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoate (Rha-Rha-C10), as well as their mono-rhamnolipid congeners Rha-C10-C10 and Rha-C10. The development of more sensitive analytical techniques has lead to the further discovery of a wide diversity of rhamnolipid congeners and homologues (about 60) that are produced at different concentrations by various Pseudomonas species and by bacteria belonging to other families, classes, or even phyla. For example, various Burkholderia species have been shown to produce rhamnolipids that have longer alkyl chains than those produced by P. aeruginosa. In P. aeruginosa, three genes, carried on two distinct operons, code for the enzymes responsible for the final steps of rhamnolipid synthesis: one operon carries the rhlAB genes and the other rhlC. Genes highly similar to rhlA, rhlB, and rhlC have also been found in various Burkholderia species but grouped within one putative operon, and they have been shown to be required for rhamnolipid production as well. The exact physiological function of these secondary metabolites is still unclear. Most identified activities are derived from the surface activity, wetting ability, detergency, and other amphipathic-related properties of these molecules. Indeed, rhamnolipids promote the uptake and biodegradation of poorly soluble substrates, act as immune modulators and virulence factors, have antimicrobial activities, and are involved in surface motility and in bacterial biofilm development

Potential therapeutic applications of microbial surface-activecompounds

Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies

Synthesis and Characterization of a New PAMAM Metallodendrimer for Antimicrobial Modification of Cotton Fabric

The synthesis and spectral characterization of a new PAMAM metallodendrimer modified with four 4-hexylamino-1,8-naphthalimide units was described. The chemical structure of metallodendrimer has been analyzed with Fourier transform infrared spectroscopy, electronic, nuclear magnetic resonance spectroscopy, and scanning electron microscopy (SEM) analysis. The antimicrobial activity of PAMAM dendrimer and its Zn complex [Zn(D)(NO)] was investigated in agar medium and in meat-peptone broth against several pathogenic bacteria and yeasts. The antimicrobial screening showed good inhibition activity of the compounds better expressed against the test Gram-positive bacteria and yeasts. The antimicrobial efficacy of cotton fabrics treated with each of the dendrimers was evaluated, and their anti-adhesive and biofilm inhibiting potential was analyzed by SEM. The complex [Zn(D)(NO)] showed stronger antimicrobial and biofilm inhibiting abilities than those of the ligand. The cytotoxicity effect of the dendrimers was also investigated in vitro in model HEp-2 cell line.The authors acknowledge Grant No H09/03-2016, Fund “Scientific Research”, Ministry of Education and Science of Bulgaria. IG and PB also acknowledge COST CA15114 “Anti-MIcrobial Coating Innovations to prevent infectious diseases (AMICI)Peer Reviewe

Synthesis and spectroscopic properties of a new fluorescent acridine hyperbranched polymer: Applications to acid sensing and as antimicrobial agent

The synthesis of a hyperbranched polyesteramide functionalized with 6 acridine groups (P1000-ACRID) is described, and its photophysical properties compared with its low molecular weight reference compound (ACRIDyne). The hyperbranched polymer does not show aggregation of the acridine groups neither in solution nor in solid polymer matrices. The behavior of both chromophores as fluorescent acid sensors has been studied in solution and in solid polymer films, showing an increase in their fluorescence emission. The stoichiometry of the protonation reaction has been calculated, showing that ACRYDyne is able to protonate twice both in solution and in solid polymer matrices, whereas P1000-ACRID only protonates once. The sensing sensitivity of the compounds is consistent with this. The antimicrobial activity of the hyperbranched polymer has been tested against five bacteria (Gram positive and Gram negative) and two yeasts, showing high antimicrobial activity. The biocompatibility of low- and high-molecular weight compounds has been studied towards two mammalian cell lines (C2C12 and Swiss3T3), and the hyperbranched polymer shows higher biocompatibility than its low-molecular weight reference compound. P1000-ACRID allows enough cellular viability when used in its biofunctional concentration range.Financial support provided by the Ministerio de Economía y Competitividad (MINECO) through the Projects MAT 2009-09671, MAT 2012-31709 and MAT2013-42957-R is acknowledged. IG and EVT acknowledge Grant№H09/03-2016, Fund “Scientific Research”, Ministry of Education and Science of Bulgaria. DA acknowledges Consejería de Economía, Empleo y Hacienda (CAM) through PEJ15/BIO/AI-0511. PB and IG acknowledge COST Action CA15114 “Anti-MIcrobial Coating Innovations to prevent infectious diseases” (AMICI).Peer Reviewe