Growth Of Phytopathogenic Fungi Research Articles

Hordenine is responsible for plant defense response through jasmonate-dependent defense pathway

Organic agriculture does not rely on synthetic chemical fungicides. An alternative pest management strategy to chemical fungicides is the use of bioactive natural compounds. Hordenine [4-(2-dimethylaminoethyl)] is a phenethylamine alkaloid found in barley. Although hordenine has various pharmacological effects, including antibiotic activity against microorganisms, no studies have been carried out to investigate the inhibitory effects of hordenine on phytopathogenic fungal infection in host plants. Both grape downy mildew and strawberry anthracnose were suppressed by hordenine treatment. Hordenine had no effect on mycelial growth of phytopathogenic fungi, whereas plant defense response through the jasmonate-dependent defense pathway was enhanced in hordenine-treated plants. The concern over environmental pollution has led to the introduction of new pesticides, including bioactive natural compound based pesticide. Hordenine may be used in organic agriculture as an innovative elicitor of plant defense response to downy mildew and anthracnose.

Antifungal activity of essential oils derived from some plants against phytopathogenic fungi

Essential oils were extracted from different plant species (Acorus calamus, Artemisia nilagerica, Erigeron Canadensis) to evaluate their effect on the growth of four phytopathogenic fungi viz. Alternaria alternata, Botrytis cinerea, Fusarium oxysporum and Penicillium expansum following poisoned food technique method. Different concentration of oil such as 125ppm, 250ppm, 500ppm, 1000ppm and 5000ppm were taken to evaluate the effect. There was 100% inhibition in the growth of phytopathogenic fungi at 5000 and 1000ppm concentration by essential oil of A. calamus. At 500ppm concentration also 100% inhibition was found up to 7th day on F. oxysporum. Essential oil of A. nilagirica inhibits the growth of all phytopathogenic fungi at higher concentration. In case of P. expansum at 5000ppm concentration 100% inhibition was recorded even after 15 days of incubation. The decrease in colony diameter or growth of fungus was corresponding to the concentration of oil. In comparison to others two, essential oil of Erigeron Canadensis was less effective against phytopathogenic fungi. It can be stated on the basis of results that the use of Acorus calamus and Artemisia nilagirica essential oil could be an alternative to synthetic fungicides for management of post harvest phytopathogenic fungal diseases caused by A. alternata, B. cinerea, F. oxysporum and P. expansum.

Cellulose acetate active films incorporated with oregano ( Origanum vulgare ) essential oil and organophilic montmorillonite clay control the growth of phytopathogenic fungi

The aim of the present study was to produce active films based on cellulose acetate (CAc) incorporated with different concentrations of oregano essential oil (OEO) and organophilic montmorillonite clay (MMT30B) to control the growth of phytopathogenic fungi. The active films were characterized by ATR-FTIR, XRD, TEM, mechanical resistance, WVTR, OTR, thermal stability, and antifungal activity against the phytopatogens Alternaria alternata, Geotrichum candidum, and Rhizopus stolonifer. The CAc-based active films presented high antifungal activity against the tested phytopathogens, mainly in vapor phase. MMT30B exhibit good dispersion in CAc matrix, resulting in a partially exfoliated conformation. In this way, MMT30B significantly increased films’ rigidity and thermal resistance while reduced OTR. OEO acted as plasticizer, facilitating MMT30B dispersion. Also, OEO increased extensibility and decreased WVTR of CAc-based films. Both OEO and MMT30B slightly improved the thermal resistance of films. The active films developed here denote a potential packaging system for postharvest conservation purposes.

Phytotoxic and antimicrobial activity of volatile and semi-volatile organic compounds from the endophyte Hypoxylon anthochroum strain Blaci isolated from Burseralancifolia (Burseraceae).

To evaluate the phytotoxic, antifungal and antioomycete activity; and, determine the chemical composition of the volatile organic compounds (VOCs) and semi-volatile metabolites produced by the endophyte Hypoxylon anthochroum strain Blaci isolated from Bursera lancifolia. Based on its macro- and micro-morphological features, the strain Blaci was identified as Nodulisporium sp.; partial analysis of its ITS1-5.8-ITS2 ribosomal gene sequence revealed the identity of the teleomorphic stage of the fungus as H.anthochroum. Phytotoxic and antimicrobial activities of VOCs, and culture medium and mycelium organic extracts from H.anthochroum Blaci were determined by simple and multiple antagonism bioassays, and gas phase and agar dilution bioassays respectively. The volatile and semi-volatile metabolites were identified by gas chromatography-mass spectrometry. VOCs from a 5-day H.anthochroum strain Blaci culture caused the inhibition of seed germination, root elongation and seedling respiration on Amaranthus hypochondriacus, Panicum miliaceum, Trifolium pratense and Medicago sativa. In addition, extracts, phenylethyl alcohol and eucalyptol main compounds present in the VOCs and extract displayed a high phytotoxic activity, inhibiting the three physiological processes on the four test plants in a concentration-dependent manner. The results revealed that H.anthochroum strain Blaci produces a mixture of VOCs. These VOCs showed a strong phytotoxic activity on seed germination, root elongation, and seedling respiration of four plants and slightly affected the growth of phytopathogenic fungi and oomycetes. Also, the culture medium and mycelium extracts of H.anthochroum showed a high phytotoxic activity on the four test plants and, generally, the culture medium extract was more phytotoxic than the mycelium extracts. This work firstly reports the phytotoxic activity of volatile and semi-volatile compounds produced by the endophyte H.anthochroum strain Blaci on seed germination, root elongation, and seedling respiration of four different plants; consequently, these compounds could be useful in biocontrol of weeds and plant pathogens.

Total Polyphenols, Antioxidant, Antimicrobial and Allelopathic Activities of Spend Coffee Ground Aqueous Extract

Spend ground coffee is largely produced worldwide, representing a residue that still present several bioactive compounds. The objective of this study was to evaluate the antimicrobial, antioxidant and herbicide activities of aqueous extract of coffee grounds, obtained at the ratio of 10 g/L (mass of waste/water volume). Spend ground coffee aqueous extract presented total polyphenol concentration of 5.66 mg GAE/g, ABTS scavenging activity of 80.5 % and iron chelating activity of 44.2 %. The results also showed that spend ground coffee extract did not inhibit the growth of phytopathogenic fungi or the foodborne pathogenic bacteria tested. On the other hand, the extract presented allelopathic activity by inhibiting the lettuce seed germination, reducing seed germination parameters and the germination speed index. Thus, the results indicate that the aqueous extract of coffee grounds has the potential to be used as a natural organic crop herbicide.

Identification, solid-state fermentation and biocontrol effects of Streptomyces hygroscopicus B04 on strawberry root rot

Root rot is one of the major constraints on strawberry production worldwide, and no effective control measure is available yet. Therefore, the objective of this study was to develop a new bio-agent for controlling this disease. The antagonistic strain B04 was isolated from the rhizosphere soil of a healthy strawberry plant, and it strongly inhibited the growth of phytopathogenic fungi, especially that of Fusarium oxysporum. Strain B04 was identified as Streptomyces hygroscopicus by morphological and cultural traits and by 16S rRNA gene sequence analysis. Strain B04 could utilize numerous carbon sources and produce extracellular fungal cell wall-degrading enzymes including chitinase, β-1,3-glucanase, cellulase and protease. Agro-industrial waste materials, specifically wheat bran and vermicompost, were used for solid-state fermentation with strain B04 to produce bioorganic fertilizer. On the seventh day of fermentation, the spore number peaked at 5.3×1010 CFUg−1. Pot and field experiments were performed to evaluate the effects of bioorganic fertilizer B04 (BOF-B04) on the infested soils. Each experiment included three groups: (1) control treatment, (2) organic fertilizer, and (3) bioorganic fertilizer B04. BOF-B04 significantly increased the fresh weight of strawberry plants compared to the control and also decreased the incidence of root rot. The biocontrol efficiencies of BOF-B04 were 63.35% and 56.77% in pot and field experiments, respectively. Moreover, application of BOF-B04 also altered the microbial community structure of the rhizosphere soil. The number of fungi in rhizosphere soil decreased markedly, by 82.43% compared to the control. In contrast, bacterial and actinomycete densities were dramatically higher than in the control. Application of BOF-B04 decreased the levels of stress-related enzyme activity and of malondialdehyde compared to the control. Consequently, this study showed that bioorganic fertilizer B04 is a potential biocontrol agent for controlling strawberry root rot.

In Vitro Antagonism between Phytopathogenic Fungi Sclerotium rolfsii and Trichoderma Strains

Six Trichoderma strains (collected from IARI, New Delhi and MTCC, Chandigarh) were tested for their ability to inhibit soil born pathogenof groundnut mainly Sclerotium rolfsii (causing stem rot on groundnut). Morphological observations of Trichoderma strains as well asphytopathogenic fungi S. rolfsii were made from culture grown at 28 0C for about one week on PDA media. The radial growth, fastest growthand coiling of test fungus of various Trichoderma strains on plant pathogenic fungi S. rolfsii were examined under LEICA phase contrastbinocular light microscope. In vitro percent growth inhibition of S.rolfsii by various Trichoderma strain was recorded at 5 days after inoculationat 28 oC in the 90 cm petriplates. Results obtained from the antagonism study indicated that Trichoderma viride (NBAII Tv 23) inhibited 61%growth of phytopathogenic fungi S. rolfsii followed by T. harzianum (NBAII Th1) (55% growth inhibition of pathogen). This suggested thatamong different Trichoderma strains, T. viride was the best bio-control agent to inhibit in vitro growth of phytopathogen S.rolfsii whichotherwise cause stem rot disease in groundnut.DOI: http://dx.doi.org/10.3126/ijasbt.v3i1.11845 Int J Appl Sci Biotechnol, Vol. 3(1): 16-19

Mo-CBP3, an antifungal chitin-binding protein from Moringa oleifera seeds, is a member of the 2S albumin family.

Mo-CBP3 is a chitin-binding protein from M. oleifera seeds that inhibits the germination and mycelial growth of phytopathogenic fungi. This protein is highly thermostable and resistant to pH changes, and therefore may be useful in the development of new antifungal drugs. However, the relationship of MoCBP3 with the known families of carbohydrate-binding domains has not been established. In the present study, full-length cDNAs encoding 4 isoforms of Mo-CBP3 (Mo-CBP3-1, Mo-CBP3-2, Mo-CBP3-3 and Mo-CBP3-4) were cloned from developing seeds. The polypeptides encoded by the Mo-CBP3 cDNAs were predicted to contain 160 (Mo-CBP3-3) and 163 amino acid residues (Mo-CBP3-1, Mo-CBP3-2 and Mo-CBP3-4) with a signal peptide of 20-residues at the N-terminal region. A comparative analysis of the deduced amino acid sequences revealed that Mo-CBP3 is a typical member of the 2S albumin family, as shown by the presence of an eight-cysteine motif, which is a characteristic feature of the prolamin superfamily. Furthermore, mass spectrometry analysis demonstrated that Mo-CBP3 is a mixture of isoforms that correspond to different mRNA products. The identification of Mo-CBP3 as a genuine member of the 2S albumin family reinforces the hypothesis that these seed storage proteins are involved in plant defense. Moreover, the chitin-binding ability of Mo-CBP3 reveals a novel functionality for a typical 2S albumin.

English

Six Trichoderma strains (collected from IARI, New Delhi and MTCC, Chandigarh) were tested for their ability to inhibit soil-borne pathogen of groundnut mainly Sclerotium rolfsii (causing stem rot on groundnut). In vitro percent growth inhibition of S. rolfsii by various Trichoderma strains were recorded at 5th day after inoculation (DAI). Results obtained from the antagonism study indicated that Trichoderma viride (NBAII Tv 23) inhibited 61% growth of phytopathogenic fungi S. rolfsii followed by Trichoderma harzianum (NBAII Th1) (55% growth inhibition of pathogen). The specific activities of cell wall degrading enzymes chitinase, β-1,3 glucanase, protease and cellulase were tested during different incubation period (48, 72 and 96 h) when Trichoderma spp. grew in the presence of pathogen cell wall in synthetic media. The antagonist T. viride (NBAII Tv 23) induced higher chitinase and protease activity. The growth inhibition of pathogen during antagonism were positively correlated with coiling pattern of antagonists at 14th day after inoculation (DAI) as well as with the induction of chitinase, β-1,3 glucanase and total phenol content. However, the amount of cellulase and polygalacturonase recorded was least in these antagonists treatment. A significant positive correlation (p = 0.01) between percentage growth inhibition of test fungus and lytic enzymes (chitinase, β-1,3-glucanase and protease) in the culture medium of antagonist treatment established a relationship to inhibit growth of fungal pathogen by increasing the levels of these enzymes. Among all the tested Trichoderma strains, T. viride (NBAII Tv 23) was found to be the best strain to be used in biological control of plant pathogen S. rolfsii. Key words: Antagonism, soil-borne pathogens, lytic enzyme, Trichoderma, biocontrol agent.

Multifunctional amaranth cystatin inhibits endogenous and digestive insect cysteine endopeptidases: A potential tool to prevent proteolysis and for the control of insect pests.

In a previous study, the amaranth cystatin was characterized. This cystatin is believed to provide protection from abiotic stress because its transcription is induced in response to heat, drought, and salinity. It has also been shown that recombinant amaranth cystatin inhibits bromelain, ficin, and cysteine endopeptidases from fungal sources and also inhibits the growth of phytopathogenic fungi. In the present study, evidence is presented regarding the potential function of amaranth cystatin as a regulator of endogenous proteinases and insect digestive proteinases. During amaranth germination and seedling growth, different proteolytic profiles were observed at different pH levels in gelatin-containing SDS-PAGE. Most of the proteolytic enzymes detected at pH 4.5 were mainly inhibited by trans-epoxysuccinyl-leucyl amido(4-guanidino)butane (E-64) and the purified recombinant amaranth cystatin. Furthermore, the recombinant amaranth cystatin was active against insect proteinases. In particular, the E-64-sensitive proteolytic digestive enzymes from Callosobruchus maculatus, Zabrotes subfasciatus, and Acanthoscelides obtectus were inhibited by the amaranth cystatin. Taken together, these results suggest multiple roles for cystatin in amaranth, specifically during germination and seedling growth and in the protection of A. hypochondriacus against insect predation. Amaranth cystatin represents a promising tool for diverse applications in the control of insect pest and for preventing undesirable proteolytic activity.

Nematicidal activity of Lysobacter capsici YS1215 and the role of gelatinolytic proteins against root-knot nematodes

Lysobacter capsici YS1215 is a soil-borne strain that could inhibit the growth of phytopathogenic fungi, including Phytophthora capsici, Rhizoctonia solani and Fusarium oxysporum, as well as root-knot nematodes. The effect of different concentrations of bacterial culture filtrate (BCF) of L. capsici YS1215 on the mortality of second-stage juveniles (J2) of Meloidogyne incognita was studied using 24-well plates. The J2 mortality increased with increasing concentrations of BCF. YS1215 also produces gelatinases in the culture filtrate. To study its role in nematicidal activities, the partial purification and the characterisation of gelatinolytic proteins were done from the culture medium of the YS1215. The partially purified proteins showed three clear bands with molecular weights estimated using zymography to be 255.7, 232.1 and 146.4 kDa. The optimal pH and temperature for the proteins were 8.0 and 40°C, respectively. The activity of the proteins was inhibited by ethylenediaminetetraacetic acid, FeCl3 and 1,10-phenanthroline, whereas it was activated by MnCl2. The proteins may belong to the group of metalloproteases. Moreover, the proteins could hydrolyse skimmed milk, collagen, gelatin and bovine serum albumin (BSA) as substrates, but not casein. The proteins could induce 75% J2 mortality in five days and degrade the J2 bodies. The present study demonstrates the role of the gelatinolytic proteins in the nematicidal potential of L. capsici YS1215.

The rhizobacterium Arthrobacter agilis produces dimethylhexadecylamine, a compound that inhibits growth of phytopathogenic fungi in vitro

Plant diseases caused by fungal pathogens such as Botrytis cinerea and the oomycete Phytophthora cinnamomi affect agricultural production worldwide. Control of these pests can be done by the use of fungicides such as captan, which may have deleterious effects on human health. This study demonstrates that the rhizobacterium Arthrobacter agilis UMCV2 produces volatile organic compounds that inhibit the growth of B. cinerea in vitro. A single compound from the volatile blends, namely dimethylhexadecylamine (DMHDA), could inhibit the growth of both B. cinerea and P. cinnamomi when supplied to the growth medium in low concentrations. DMHDA also inhibited the growth of beneficial fungi Trichoderma virens and Trichoderma atroviride but at much higher concentrations. DMHDA-related aminolipids containing 4, 8, 10, 12, and 14 carbons in the alkyl chain were tested for their inhibitory effect on the growth of the pathogens. The results show that the most active compound from those tested was dimethyldodecylamine. This effect correlates with a decrease in the number of membrane lipids present in the mycelium of the pathogen including eicosanoic acid, (Z)-9-hexadecenoic acid, methyl ester, and (Z)-9-octadecenoic acid, methyl ester. Strawberry leaflets treated with DMHDA were not injured by the compound. These data indicate that DMHDA and related compounds, which can be produced by microorganisms may effectively inhibit the proliferation of certain plant pathogens.

Cloning and Heterologous Expression of Serine Protease SL41 Related to Biocontrol in Trichoderma harzianum

Serine proteases are highly conserved among fungi and considered to play a key role in different aspects of fungal biology. These proteases are involved in fungal growth and have been related to biocontrol processes. To assess the functional role of serine proteases from Trichoderma harzianum T88, an effective biocontrol agent, on inhibition of phytopathogenic fungi, a gene (SL41) encoding a serine protease was isolated by 5′ and 3′ RACE (rapid amplification of cDNA ends). Northern blot analysis indicated that SL41 was induced in response to cell walls of different fungi. This protease gene was expressed in Saccharomyces cerevisiae under the control of the galactose-inducible GAL1 promoter. After induction, the enzyme activity was culminated (16.2 units ml^-1) at 60 h of cultivation. The optimal enzyme reaction temperature was 40°C and optimal pH was 10.5. Northern blot analysis indicated that the amount of the transcripts increased with the culture time in agreement with the measured enzyme activity. Antifungal activity of serine protease against five phytopathogens was investigated in vitro. It can inhibit the mycelial growth of phytopathogenic fungi and exerted broad spectrum antifungal activity against phytopathogenic fungi. This is the first time that the different regulation of serine protease in T. harzianum response to five phytopathogenic fungi was shown, the protease was functionally expressed in a heterologous host, and its antagonistic activity was evaluated in vitro.

Study of antifungal activities of seven essential oils from some Iranian medicinal plants against various postharvest phytopathogenic fungi

The aim of this study was to find the antifungal activities of seven essential oils from some Iranian medicinal plants that have maximum (100%) inhibition effect on the mycelium growth of postharvest phytopathogenic fungi. Among 20 examined species belonging to three families, only 7 species could stop the mycelium growth of phytopathogenic fungi. The selected plants include Trachyspermum ammi, Zataria multiflora Boiss., Satureia hortensis, Caryophillum aromaticus, Menthe piperita, Cuminum cyminum L. and Carum carvi, and fungi include Aspergillus flavus, Botrytis cinerea, Penicillium italicum, Penicillium expansum, Penicillium commune, Rhizopus stolonifer and Rhizopus lyococcus. The results showed that the essential oil of these plants could stop the mycelium growth at 500 ppm, but could not completely inhibit the spore germination, however reduced the spore germination to 80–90%. Among the fungi Rhizopus stolonifer and Rhizopus lyococcus are more resistant to the inhibition effects of essential oils. Among the plants, Cuminum cyminum L. and Carum carvi were slightly weaker than other plants. Also except for Cuminum cyminum L. and Carum carvi, the essential oils of other plants had fungicide effect while these two plants in most cases had fugistatic effect. The results showed that these essential oils can be used as an effective alternative control method.

Rhizobacteria of pepper (Piper nigrum) and their antifungal activities

The purpose of this study is to isolate and select indigenous soil Bacillus bacteria capable of developing multiple mechanisms of action related to the biocontrol of phytopathogenic fungi affecting pepper vines (Piper nigrum). The screening procedure consisted of antagonism tests against a panel of phytopathogenic fungi, in vitro detection of the antifungal products and root colonization assay. Four isolates, identified and designated as Bacillus amyloliquefaciens (WW6), Bacillus atrophaeus (MPB), Bacillus subtilis (CBF) and Bacillus vallismortis (WW14) were selected for further studies. All bacterial isolates obtained where effective for the in vitro control of the growth of phytopathogenic fungi, where the control mechanisms used by the bacteria involved the secretion of protease and cellulase enzyme that are responsible for fungal cell wall hydrolysis. The bacteria also produced volatile as well as diffusible substances. Malformation of hyphae occurred in the presence of both bacteria. Hyphae were thickened, vacuolar and many swellings occurred in them or at the tips of hyphal strand. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, and temperature) and showed a good capacity of pepper root colonization. These results suggest that all the bacterial isolates studied have an excellent potential to be used as biocontrol agents for controlling phytopathogenic fungi greenhouses at the field level.

Role of the 4-Phosphopantetheinyl Transferase of Trichoderma virens in Secondary Metabolism and Induction of Plant Defense Responses

Trichoderma virens is a ubiquitous soil fungus successfully used in biological control due to its efficient colonization of plant roots. In fungi, 4-phosphopantetheinyl transferases (PPTases) activate enzymes involved in primary and secondary metabolism. Therefore, we cloned the PPTase gene ppt1 from T. virens and generated PPTase-deficient (?ppt1) and overexpressing strains to investigate the role of this enzyme in biocontrol and induction of plant defense responses. The ?ppt1 mutants were auxotrophic for lysine, produced nonpigmented conidia, and were unable to synthesize nonribosomal peptides. Although spore germination was severely compromised under both low and high iron availability, mycelial growth occurred faster than the wild type, and the mutants were able to efficiently colonize plant roots. The ?ppt1 mutants were unable of inhibiting growth of phytopathogenic fungi in vitro. Arabidopsis thaliana seedlings co-cultivated with wild-type T. virens showed increased expression of pPr1a:uidA and pLox2:uidA markers, which correlated with enhanced accumulation of salicylic acid (SA), jasmonic acid, camalexin, and resistance to Botrytis cinerea. Co-cultivation of A. thaliana seedlings with ?ppt1 mutants compromised the SA and camalexin responses, resulting in decreased protection against the pathogen. Our data reveal an important role of T. virens PPT1 in antibiosis and induction of SA and camalexin-dependent plant defense responses.

Control of Penicillium expansum and Botrytis cinerea on pear with Thymus kotschyanus, Ocimum basilicum and Rosmarinus officinalis essential oils

The aim of this study was to test the possibility of the use of Thymus kotschyanus,Ocimum basilicum and Rosmarinus officinalis essential oils to reduce postharvest losses induced by Botrytis cinerea and Penicillium expansum in pear fruits. In this study, the antifungal activity of essential oils under in vitro condition were assayed by poison food medium method (0, 100, 200, 300, 400 and 500 μL/L) and under in vivo condition by spraying different essential oil concentrations (0, 100, 300 and 500 μL/L) on inoculated pear fruits. Results of the present study showed that T. kotschyanus had the highest antifungal activity under in vitro condition and completely inhibited fungal growth at concentrations above 200 μL/L. Results of in vivo studies showed that T. kotschyanus oil decreased the disease severity and number of infected pear fruits inoculated with B. cinerea and P. expansum. Measurement of quality sensors of pear fruits showed that essential oil treatment increased the taste of fruits. T. kotschyanus oil also reduced and in the contrast O. basilicum oil increased the firmness of oil-treated fruits. Results of this study showed that T. kotschyanus had good inhibitory effect on growth of phytopathogenic fungi and may be used as a new tool for preservation and extension of shelf-life of pear fruits. Key words: Essential oil, pear, Thymus kotschyanus, Ocimum basilicum, Rosmarinus officinalis, antifungal.

Brevibacillus laterosporus strain BPM3, a potential biocontrol agent isolated from a natural hot water spring of Assam, India

A bacterial strain designated as BPM3 isolated from mud of a natural hot water spring of Nambar Wild Life Sanctuary, Assam, India, strongly inhibited growth of phytopathogenic fungi ( Fusarium oxysporum f. sp. ciceri, F. semitectum, Magnaporthe grisea and Rhizoctonia oryzae) and gram-positive bacterium ( Staphylococcus aureus). The maximum growth and antagonistic activity was recorded at 30 °C, pH 8.5 when starch and peptone were amended as carbon and nitrogen sources, respectively. In greenhouse experiment, this bacterium (BPM3) suppressed blast disease of rice by 30–67% and protected the weight loss by 35–56.5%. The maximum disease protection (67%) and weight loss protection (56.5%) were recorded when the bacterium was applied before 2 days of the pathogen inoculation. Antifungal and antibacterial compounds were isolated from the bacterium which also inhibited the growth of these targeted pathogens. The compounds were purified and on spectroscopic analysis of a purified fraction having R f 0.22 which showed strong antifungal and antibacterial activity indicated the presence of C–H, carbonyl group, dimethyl group, –CH 2 and methyl group. The bacterium was characterized by morphological, biochemical and molecular approaches and confirmed that the strain BPM3 is Brevibacillus laterosporus.

Recombinant amaranth cystatin (AhCPI) inhibits the growth of phytopathogenic fungi

Phytocystatins are cysteine proteinase inhibitors from plants implicated in defense mechanisms against insects and plant pathogens. We have previously characterized an amaranth cystatin cDNA and analyzed its response to different kinds of abiotic stress [37]. In order to characterize amaranth cystatin, the coding sequence was expressed in Escherichia coli using the pQE-2 vector. Recombinant cystatin was predominantly found in the soluble fraction of the cell extract. Large amounts (266 mgL(-1)) of pure recombinant protein were obtained by affinity chromatography in a single step of purification. The amaranth cystatin with a pI 6.8 and an apparent 28 kDa molecular mass inhibited papain (E.C.3.4.22.2) (Ki 115 nM), ficin (E.C.3.4.22.3) (Ki 325 nM) and cathepsin L (E.C.3.4.22.15) (Ki 12.7 nM) but not stem bromelain (E.C.3.4.22.32), and cathepsin B (E.C.3.4.22.1) activities, in colorimetric assays. Furthermore, it was able to arrest the fungal growth of Fusarium oxysporum, Sclerotium cepivorum and Rhyzoctonia solani. It was further demonstrated that recombinant AhCPI is a weak inhibitor of the endogenous cysteine proteinase activities in the fungal mycelium. These findings contribute to a better understanding of the amaranth cystatin activity and encourage further studies of this protein.

Spectroscopic, thermal and biocidal studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes of tridentate ligand having semicarbazone moieties

Mn(II), Co(II), Ni(II) and Cu(II) complexes having the general composition M(L)2X2 [where L = 2-pyridinecarboxaldehyde semicarbazone, M = Mn(II), Co(II), Ni(II) and Cu(II), X = Cl− and NO3 −] have been synthesized. All the synthesized compounds were identified and confirmed by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, EPR, electronic spectral studies and thermogravimetric analysis (TG). The Molar conductance measurements of the complexes lie in the range 209–228 Ω1 cm−1 mol−1 indicating that the complexes are 1:2 electrolytic in nature. Thus the complexes may be formulated as [M(L)2]X2. The magnetic moment measurements of the complexes indicate that all the complexes are in high-spin state. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II), Co(II) and Ni(II) complexes whereas tetragonal geometry for Cu(II) complexes. The thermal studies suggested that the complexes are more stable compared with free ligand. This fact was supported by calculating the thermodynamic parameters by using Horowitz–Metzger (HM) and Coats–Redfern (CR) equations. The free ligand and its metal complexes were also evaluated against the growth of phytopathogenic fungi and bacteria in vitro.