Characterisation of Streptomycin resistant mutants of biocontrol Bacillus strains

A good antibiotic-producing Bacillus subtilis and an elevated extracellular enzyme-secreting Bacillus amyloliquefaciens biocontrol strain were investigated. The B. subtilis strain produces non-ribosomal oligopeptides: iturin, surfactin and fengycin. These cyclic lipopeptides have antifungal and antibacterial effects. The B. amyloliquefaciens strain secrets many extracellular enzymes (proteases, chitinases, cellulases and lipases); these have great significance in the antagonism. Kurosawa and co-workers reported elevated protease and P-amylase secretion from streptomycin-resistant B. subtilis mutants. We isolated twenty spontaneous streptomycin resistant mutants from our B. subtilis strain and four spontaneous streptomycin resistant mutants from the B. amyloliquefaciens strain. We investigated the extracellular enzyme and antibiotic production of the mutants. Some of the mutants showed elevated enzyme and antibiotic secretion. The rpsL gene in theses spontaneous streptomycin resistant mutants, were sequenced and point mutations were detected in it, so very likely the changes of the structure of the rpsL protein is responsible in some cases for the elevated enzyme and depsipeptide production

Isolation and characterization of phanerochaete strains suitable for bioremediation purposes

The most unsettled problem of organic farmlands are related to the following two groups of pollutants: POP (Persistent Organic Pollutant) and PAH (Polycyclic Aromatic Hydrocarbon) compounds. These are recognized as being directly toxic to biota even at low concentration; furthermore, they accumulate in organisms. The white rot fungus Phanerochaete chrysosporium has a potential for bioremediation of soils polluted by xenobiotic compounds. Our aim was to isolate of P. chrysosporium strains, which can efficiently degrade POP and PAH compounds by their enzyme systems. A new selective medium, containing rose bengal, dichloran and carbendazim was used to isolate P. chrysosporium from soil. We isolated one P. sordida and five P. chrysosporium strains from Hungarian environmental samples. In soil microcosm experiments the investigated Phanerochaete strains were able to degrade distinct herbicides and parabens in soils of different origin (agricultural field soil, garden soil and sandy soil)

Characterization of novel surfactin isoforms and the effects of different cultivation parameters on their production by bacillus subtilis

Surfactin is a lipopeptide-type biosurfactant produced mainly by the gram-positive microorganism Bacillus subtilis. It consists of a peptide loop of seven amino acids and a hydrophobic fatty acid chain (C12 – C16). Surfactins are proved to exhibit various biological activities, such as anti-tumor, anti-viral and anti-inflammatory effects. According to these properties, different therapeutic and environmental applications of surfactins are considered. The chemical composition of surfactins could be varied in the length of the fatty acid chain and in the sequence of the amino acids of the peptide chain generating a wide spectrum of different homologues and isomers. The chemical composition of these isoforms could be elucidated via mass spectrometry by the analysis of MSn fragmentation pattern. Furthermore, depending on the cultivation conditions, the production of surfactins are affected resulting in various rates of the different isoforms produced. In this work a mixture of surfactins were extracted from the strain Bacillus subtilis (SZMC 6179J) and were examined by HPLC-ESI-IT-MS technique. To increase the separation of the components with higher masses a gradient elution was applied using a nonpolar solvent system, which led to their proper elution and characterization of their structures. Both the length of the linked fatty acids and the peptide sequences were also investigated during the MS2 spectra analyses of the sodiated precursor ions. The results led to the discovery of a novel, recently unknown group of surfactin forms possessing glutamic acid in as the fifth amino acid residue instead of the aspartic acid described previously at this position. To examine the effects of the culture media on the surfactin production, it was modified with various carbon sources and metal ions. It was reaffirmed that altering the cultivation parameters could enable the improved production of certain surfactin variants, which could serve possibility for their further preparative purification and structural elucidation. The research was supported through the New National Excellence Program of the Ministry of Human Capacities

Isolation and characterization of phanerochaete strains suitable for bioremediation purposes

The most unsettled problem of organic farmlands are related to the following two groups of pollutants: POP (Persistent Organic Pollutant) and PAH (Polycyclic Aromatic Hydrocarbon) compounds. These are recognized as being directly toxic to biota even at low concentration; furthermore, they accumulate in organisms. The white rot fungus Phanerochaete chrysosporium has a potential for bioremediation of soils polluted by xenobiotic compounds. Our aim was to isolate of P. chrysosporium strains, which can efficiently degrade POP and PAH compounds by their enzyme systems. A new selective medium, containing rose bengal, dichloran and carbendazim was used to isolate P. chrysosporium from soil. We isolated one P. sordida and five P. chrysosporium strains from Hungarian environmental samples. In soil microcosm experiments the investigated Phanerochaete strains were able to degrade distinct herbicides and parabens in soils of different origin (agricultural field soil, garden soil and sandy soil)

Degradation of phenol derivatives by a phanerochaete chrysosporium strain

The white rot fungus Phanerochaete chrysosporium has significant pollutant-degrading capabilities with its oxidoreductases. The lignin-degrading enzyme system of this fungus also allows the breakdown of different organic pollutants (xenobiotics). The most significant enzymes in these processes are the lignin peroxidase and the manganese peroxidase. In this study, Phanerochaete chrysosporium strains were isolated from various Hungarian habitats. It was revealed, that one of these strains (Pha78) seems to be very promising for such remediation purposes. The degradation of different phenol derivatives by this isolate was investigated both in lignin peroxidase and manganese peroxidase inductive media. The starting concentrations of phenol derivative compounds were 20 mg l -1 . The amounts of the phenolic compounds in the media were measured by the colorimetric aminoantipyrine method. The tested Phanerochaete strain was able to degrade different phenol derivatives efficiently, especially in manganese peroxidase-inductive medium

A Composite Bioinoculant Based on the Combined Application of Beneficial Bacteria and Fungi

A composite soil bioinoculant containing beneficial bacteria and fungi was developed for biocontrol of plant pathogens, phosphorous mobilization, stem degradation, humification, and nitrogen fixation. A Trichoderma asperellum isolate with outstanding in vitro antagonistic abilities toward a series of plant pathogenic fungi was included as a potential biocontrol component. The selected strain was also shown to promote growth and increase photosynthetic activity of tomato plants. For phosphorous mobilization and stem degradation, a Trichoderma atrobrunneum strain was selected, which produced cellulose-degrading enzymes even in the absence of stem residues, while this ability increased 10–15-fold in the presence of ground maize stem. The strain was also shown to produce large amounts of enzymes liberating organically bound phosphorous, as well as cellulase and xylanase activities in solid-state fermentation on various plant residues. A Streptomyces albus strain with excellent peroxidase-producing abilities was selected as a potential humus-producing component, while an Azotobacter vinelandii strain with the potential to provide excess nitrogen for crops was included for nitrogen fixation. The assembled soil bioinoculant had positive effect on the uptake of certain important macro- and microelements (potassium, sodium, and manganese) from the soil by field-grown tomato plants. The applied screening strategy proved to be applicable for the assembly of a composite soil bioinoculant with notable application potentials