Maximum Antagonism Research Articles

Development of Biological Coating from Novel Halophilic Exopolysaccharide Exerting Shelf-Life-Prolonging and Biocontrol Actions for Post-Harvest Applications.

The literature presents the preserving effect of biological coatings developed from various microbial sources. However, the presented work exhibits its uniqueness in the utilization of halophilic exopolysaccharides as food coating material. Moreover, such extremophilic exopolysaccharides are more stable and economical production is possible. Consequently, the aim of the presented research was to develop a coating material from marine exopolysaccharide (EPS). The significant EPS producers having antagonistic attributes against selected phytopathogens were screened from different marine water and soil samples. TSIS01 isolate revealed the maximum antagonism well and EPS production was selected further and characterized as Bacillus tequilensis MS01 by 16S rRNA analysis. EPS production was optimized and deproteinized EPS was assessed for biophysical properties. High performance thin layer chromatography (HPTLC) analysis revealed that EPS was a heteropolymer of glucose, galactose, mannose, and glucuronic acid. Fourier transform infrared spectroscopy, X-ray diffraction, and UV-visible spectra validated the presence of determined sugars. It showed high stability at a wide range of temperatures, pH and incubation time, ≈1.63 × 106 Da molecular weight, intermediate solubility index (48.2 ± 3.12%), low water holding capacity (12.4 ± 1.93%), and pseudoplastic rheologic shear-thinning comparable to xanthan gum. It revealed antimicrobial potential against human pathogens and antioxidants as well as anti-inflammatory potential. The biocontrol assay of EPS against phytopathogens revealed the highest activity against Alternaria solani. The EPS-coated and control tomato fruits were treated with A. solani suspension to check the % disease incidence, which revealed a significant (p < 0.001) decline compared to uncoated controls. Moreover, it revealed shelf-life prolonging action on tomatoes comparable to xanthan gum and higher than chitosan. Consequently, the presented marine EPS was elucidated as a potent coating material to mitigate post-harvest losses.

Acremonium kilense as an endophytic bioagent against turmeric (Curcuma longa L.) diseases and tolerance to plant protection chemicals

Turmeric (Curcuma longa L), “the golden spice of life” is one of most essential spice use as an important ingredient in culinary all over the world. Present investigation was done to understand the biocontrol potential of various endophytic microbes associated with turmeric against the pathogen causing rhizome rot disease of turmeric (Pythium sp.). A total of 15 endophytic fungi isolated from different locations of Andhra Pradesh state were evaluated. It was observed that Tc ed f 1(Acremonium kilense) was found to exert maximum antagonism against the pathogen. It was also observed that Acremonium kilense is incompatible with fungicides like Bordeaux mixture, Mancozeb 75%WP, Cyamoxanil 8% + Mancozeb 64%WP and Bordeaux mixture and higher concentrations of Fenamidone 10% + Mancozeb 50% WG and insecticides like Dimethoate, Malathion and Thiomethoxam showed 100 per cent inhibition indicating its poor level of compatibility.

Efficacy of native fluorescent Pseudomonads against soil-borne phytopathogenic fungi

The present investigation was carried out to evaluate the antagonistic potential of fluorescent Pseudomonads isolated from different crop rhizospheres of zone III A and Zone II of Bihar against three soil-borne fungal phytopathogens viz., Rhizoctonia solani, Sclerotium rolfsii and Fusarium oxysporum using dual culture technique. Sixteen fluorescent Pseudomonads were isolated from different crop rhizospheric soils collected from different locations of Bhagalpur and kishanganj district. In vitro evaluation results indicated the significant differences among the fluorescent Pseudomonads in their efficacy against the test fungi. Among the sixteen fluorescent Pseudomonads tested, isolate BMGh shown maximum antagonism against Rhizoctonia solani with 55.66 per cent inhibition of pathogen over control followed by isolate whkh (47.16 per cent) and Msksn (46.22 per cent). Isolate CHGH was found least effective (15.09 per cent inhibition). Against Sclerotium rolfsii, isolate LnsB had maximum antagonism potential with 88.81 per cent inhibition of radial growth of the fungus followed by whkh (79.72 per cent inhibition) and isolate BRKH was found least effective (23.78 per cent) followed by CKSB (32.87 per cent). Isolates MZksn and BRGh were found to have maximum antagonistic potential against Fusarium oxysporum (58.74 per cent) followed by WHSB (56.65 per cent). The isolate MRKH was found least effective (15.39 per cent) followed by MSKSN (20.29 per cent). The effective fluorescent Pseudomonad isolates screened under in vitro may further used for effective management of soil-borne fungal plant diseases in integrated disease management strategies and in organic farming system.

Cold-tolerant Trichoderma species for the managementof Fusarium wilt of tomato plants

Cold-tolerant Trichoderma species capable of growing at 5 °C were isolated from rhizospheric soils of the western Himalayan region. Sequencing of the internal transcribed spacer region revealed that these isolates were taxonomically affiliated to Trichoderma gamsii, Trichoderma velutinum and Hypocrea lixii. The isolate showing maximum antagonism against Fusarium oxysporum f.sp. lycopersici (FOL), PETX-Behli-1 (T. gamsii), was studied for its chitinolytic ability. This isolate displayed maximum chitinolysis on chitinase detection agar, with the extracellular proteins in minimal synthetic broth (MSB) amended with colloidal chitin showing higher chitinase activities of 63.1- to 83.8-fold at 5–37 °C than those in MSB alone. Extracellular proteins of cell-free extracts of MSB amended with and without chitin contained polypeptides of 26–180 kDa. In the plate assays, the crude extract containing chitinases inhibited mycelial growth of the pathogenic fungus by 42 %. Seed bacterization and soil application of the chitin-supplemented talc-based formulation of PETX-Behli-1 challenge inoculated with FOL resulted in a significantly lower incidence (61.9 % reduction) of Fusarium wilt relative to the non-bacterized pathogen control in a greenhouse (18–20 °C). This lower incidence was associated with an increase in the plant vigor index, fruit number and fruit weight of 64.8, 205.4, and 210.8 %, respectively, relative to the pathogen control. In the native gel activity assays, PETX-Behli-1 following challenge inoculation expressed a higher intensity or an increased number of isoforms of chitinase, peroxidase and polyphenol oxidase. The results suggest that the cold-active PETX-Behli-1 may represent an important biocontrol agent to control Fusarium wilt of tomato plants grown in winter.

Salinity tolerant Trichoderma harzianum reinforces NaCl tolerance and reduces population dynamics of Fusarium oxysporum f.sp. ciceri in chickpea (Cicer arietinum L.) under salt stress conditions

The antagonistic potential of salinity tolerant (ST) Trichoderma (Th) isolates against Fusarium oxysporum f.sp. ciceri (foc) was tested, along with their capability to induce relative salt stress tolerance in chickpea with the aim to exploit their use as biological agents in reducing deleterious effects of salinity and controlling Fusarium wilt of chickpea under saline soil conditions. Under laboratory conditions, salt stress was created by supplementing nutrient medium with different concentrations of NaCl viz. 0, 70, 150 and 240 mM NaCl and a pot experiment was conducted using natural saline soil (EC – 6.6 dS m−1). Out of 45 Th isolates studied, only five isolates viz. Th-13, Th-14, Th-19, Th-33 and Th-50 were selected to be ST as these were able to grow and sporulate in growth medium containing up to 240 mM NaCl. In saline medium, ST isolates greatly surpassed salinity sensitive (SS) isolate with respect to growth rate, mycelial dry weight, sporulation and biological proficiency against foc. Out of five ST isolates that retained their tolerance to different salt stress levels, Th-14 and Th-19 showed maximum antagonism against foc. Under greenhouse conditions, chickpea plants obtained from seeds bioprimed with Th-14 and Th-19 performed well both at germination and seedling stage in comparison to control in saline soil. As compared to untreated plants, characterisation of Th treated plants confirmed that they had reinforced contents of proline along with relatively higher levels of total phenols, membrane stability index and superoxide dismutase activity while lower accumulation of hydrogen peroxide and malondealdehyde contents. ST isolates, Th-14 and Th-19 significantly reduced foc-induced wilt disease incidence in chickpea plants. The population density of both the Th isolates in rhizosphere far exceeded that of foc under both saline and non-saline soils. However, Th-14 was found more efficient in increasing relative salt stress tolerance in chickpea and reducing the foc growth in rhizosphere under present materials and conditions. These findings provide a novel paradigm for developing alternative, environmentally safe strategy to alleviate salt stress and manage fungal diseases such as foc that aggravates under saline soils.

BIOEFFICACY OF TRICHODERMA ISOLATES AGAINST PATHOGENIC FUNGI INCITING SPINACH (SPINACEA OLERACEA L.)

ABSTRACT Biological control of plant pathogens using antagonistic fungi can be successfully utilized especially within the frame work of integrated disease management system. Efficacy of different isolates of Trichoderma species against two pathogenic fungi causing leaf spot (Alternaria spinaciae) and wilt (Fusarium oxysporum f. sp. spinaciae) on spinach (Spinacea oleracea L.) by dual culture technique under in vitro conditions. Generally Trichoderma used as a biological control for the inhibition of growth of the pathogens. Different isolates i.e. Trichoderma viride (12), T. harzianum (12), T. koningii (07), T. pseudokoningii (05) and T. virens (10) strains were isolated and used for antagonistic study. Results indicated that, among T. viride isolates, Tv1 and Tv5 showed maximum antagonism, but in case of Tv7 and Tv10 showed minimum antagonism against A. spinaciae. In case of F. oxysporum f. sp. spinaciae showed significant inhibition by Tv4 and reduced the percent inhibition by Tv8 and Tv6. In case of T. harzianum isolates, Th3 and Th10 showed maximum inhibition on A. spinaciae while in F. oxysporum f. sp. spinaciae, Th5 increased the inhibition and decreased in Th3 and Th7. Trichoderma koningii showed better results in Tk7 isolate whereas decreased Tk4 over A. spinaciae, but in F. oxysporum f. sp. spinaciae reduced rate was more in Tk4 and Tk2. Isolates of T. pseudokonongii found maximum inhibition in Tp5 over A. spinaciae and significant inhibition in Tp3 over F. oxysporum f. sp. spinaciae. Trichoderma virens isolates were found significant inhibition in Tvr4 and Tvr9 and 50% reduction over A. spinaciae and Tvr4 increased the percent inhibition and decreased the Tvr7 in case of F. oxysporum f. sp. spinaciae.

Effect of Cd, Zn, and Pb Compound Pollution on Celery in a Ferric Acrisol

A pot experiment with an orthogonal experimental design L9(34) was conducted to study the combined effects of Cd, Zn, and Pb on the growth and metal content of celery grown in a ferric acrisol. The uptake of Cd, Zn, and Pb by celery was not only affected by the individual elements, but also by combinations of the elements. The effect of coexisting elements on plant uptake of the heavy metals depended on the concentration ratios of the elements. There is a given ratio where a maximum antagonism or synergism effect occurs. The combinations of elements clearly affected the dry weight of celery and the heavy metal concentration in celery. The removal rate (the ratio of plant total uptake to the total metal content in soil) was in the order of Cd > Zn > Pb, with no obvious difference between the removal rate under single pollution and that under compound pollution.

Aetiology and biological control of Fusarium wilt of pinks (Dianthus caryophyllus) using Trichoderma aureoviride

Fusarium oxysporum f.sp. dianthi (F.o.d.) was the species isolated most frequently from wilted glasshouse‐grown pinks in south‐west England, whereas F. avenaceum was less prevalent and F. culmorum was not found. Although infections by F. avenaceum, via the roots or through a cut‐stem wound, caused symptoms identical to those characterizing mild infections due to F.o.d., the former was always pathogenically weak relative to the latter. Of several organisms screened for potential antagonistic capacity towards F.o.d., using an in‐vitro dual culture plate technique, Trichoderma aureoviride, isolated as an endophyte from healthy pinks, proved most effective. Elevated temperatures substantially reduced the antagonistic capacity of micro‐organisms in both in‐vitro and in‐vivo screens, except in the case of T. aureoviride where maximum antagonism occurred at 28°C, which was near the optimum for wilt disease in pinks. The tolerance shown by T. aureoviride to a wide range of pesticides used in commercial production of pinks under cover indicated its potential in a proposed integrated disease control programme.

ATP-dep̀endent K + channel blockers antagonize morphine- but not U-504,88H-induced antinociception

The effects of four ATP-dependent K + channel blockers (hypoglycemic sulfonylureas) against morphine- and U50488H-induced antinociception were evaluated using the tail flick test in mice. None of the sulfonylureas tested significantly modified tail flick latency in control animals. However, i.c.v. pretreatment with gliquidone (0.4–1.6 μg/mouse), glipizide (2.5–10 μg/mouse), glibenclamide (10–40 μg/mouse) or tolbutamide (20–80 μg/mouse) dose dependently antagonized morphine-induced antinociception approximately equieffectively, the only difference being in potency: gliquidone > glipizide > glibenclamide > tolbutamide. This effect of sulfonylureas was very specific, since none antagonized the antinociception elicited by U50488H even at doses twice as great as the dose that induced maximum antagonism of morphine antinociception. Because morphine, but not U50488H, opens K + channels in neurons and because the order of potency of the different sulfonylureas for blocking ATP-dependent K + channels in neurons and for antagonizing morphine antinociception is the same, we suggest that morphine antinociception is mediated by the opening of ATP-dependent K + channels.

Environmental factors affecting the antagonism of Pseudomonas cepacia against Trichoderma viride

Antagonistic activity of the bacterium Pseudomonas cepacia against Trichoderma viride was greatly influenced by nutritional and environmental conditions. Xylose and trehalose strongly enhanced the antifungal activity of P. cepacia, whereas mannitol and glucose had little effect. The carbon sources that enhanced the antagonistic activity also inhibited sporulation of T. viride. Antagonism of P. cepacia was enhanced by ammonium nitrogen; however, with nitrite or nitrate there was only a little antagonism. The antagonism of P. cepacia was optimal at pH 5.0. Although P. cepacia showed maximum antagonism against T. viride at 37 degrees C, the antagonism was fairly good at temperatures as low as 18 degrees C, indicating that there is a broad range of temperature for the antifungal activity of P. cepacia.

Central oxotremorine antagonist properties of pirenzepine

Pirenzepine, the prototype M 1 muscarinic receptor antagonist, is an important compound for investigating the functional significance of M 1 receptors at the integrated level of behavior but may have limitations imposed by its physical chemistry. Like the non-selective antagonist methylatropine, pirenzepine is highly hydrophilic and crosses the blood-brain-barrier with difficulty. We compared methylatropine with pirenzepine, given intraperitonealy, as antagonists of the behavioral effects of peripheral or central muscarinic activation. Lever-press responses of male Sprague-Dawley rats were maintained under a schedule requiring 10 responses for each food delivery. Administration of oxotremorine or the quaternary analog oxotremorine-M decreased rates of responding by at least 90%. Both methylatropine and pirenzepine antagonized the behavioral effects of oxotremorine-M; maximum reversal was 70%. Although methylatropine was about 30 times more potent than pirenzepine as an antagonist of the peripheral muscarinic activity of oxotremorine-M, it was inactive as an antagonist of oxotremorine when given in doses up to 153 μmol/kg. Pirenzepine, however, reversed oxotremorine-induced behavioral effects, with a maximum antagonism of 50%. These results suggest that pirenzepine interacts with central muscarinic receptors when administered systemically without producing marked behavioral effects of its own. Systemically administered pirenzepine may thus be a useful tool in further investigations of the relevance of M 1 receptors to behavioral function.

A study of factors which determine the pharmacological response to vitamin K in coumarin anticoagulated rabbits

The pharmacological response to vitamin K has been determined by measuring prothrombin complex activity (P.C.A.) in male New Zealand White rabbits anticoagulated (P.C.A. <20%) with the long acting 4-hydroxycoumarin brodifacoum, at a dose (10 mg/kg) which produces maximum antagonism of vitamin K 1. Thus, according concurrent concepts, this animal model may be used to assess vitamin K requirements in the absence of a functional vitamin K-epoxide reductase. After intravenous administration of vitamin K 1 (1 mg/kg) P.C.A. reached a maximum (64±19%) at 3 hr and then declined at a rate which corresponds to complete inhibition of clotting factor synthesis. Vitamin K 2 (1 mg/kg) stimulated clotting factor synthesis for 2 hr, while cis-vitamin K 1, vitamin K 3, vitamin K 1 2,3-epoxide and oral administration of vitamin K 1 were ineffective. Plasma concentrations of vitamin K 1 fell steeply during the 12 hr following administration of a pharmacological dose, and then declined with a terminal half-life of 18.9 ± 9.0 hr. Comparison of the phamacodynamic and pharmacokinetic data indicated that plasma concentrations in the range 0.4–1.0 μg/ml are required for clotting factor synthesis in the limiting situation of maximum antagonism of vitamin K by coumarin anticoagulants. These findings explain why frequent and repeated administration of vitamin K 1 may be necessary during coumarin poisoning.

Differential effects of propranolol on heart rate and plasma renin activity in patients treated with minoxidil.

The relationship between PPC and its effect on minoxidil‐induced increases in PHA and heart rate was examined in 9 patients with essential hypertension. Concomitant with the minoxidil‐induced depression of mean arterial pressure (30.7 ± 3.5 mm Hg, mean ± SEM), heart rate increased from 79.1 ± 3.0 to 100.4 ± 4.6 BPM, and PHA increased from 1.12 ± 0.28 to 8.58 ± 2.83 nglmllhr. Addition of propranolol to minoxidil caused a decrease in heart rate in proportion to log PPC:Δ heart rate = 1.1 − 12.8 log PPC (r, 0.59, p &lt; 0.005)The relationship between PPC and the reduction in PHA was more complex. While a major reduction in PHA was observed at PPC in the range 20 to 60 nglmllhr, there was no consistent effect on PHA at higher PPC. Therefore, maximum antagonism of adrenergicaUy mediated increases in PHA is produced by much lower concentrations of propranolol than maximum suppression of adrenergically mediated increases in heart rate.

Alteration of avoidance and ingestive behavior after destruction of central catecholamine pathways with 6-hydroxydopamine

Alterations of shuttle-box avoidance acquisition, ingestive behavior, and catecholamine content in 4 different parts of brain were determined following bilateral infusion of 6-hydroxydopamine into the ventral tegmental area containing A-10 dopamine cell bodies, the tegmental segment of the ascending norepinephrine pathways, the globus pallidum, or the caudate-putamen. The maximum antagonism of active avoidance acquisition occurred following placement of 6-hydroxydopamine into the ventral tegmental and caudate areas. No effect on either avoidance or ingestive behavioral measures occurred after infusion of 6-hydroxydopamine into the norepinephrine pathways. Factor analysis of behavioral and biochemical data suggested that only striatal dopamine content bore a high relationship to avoidance behavior, while ingestive behavioral measures were highly related to both striatal and limbic dopamine content. Results suggest a functional—anatomical differentiation of dopamine pathways in brain.

Antagonism of the antihypertensive action of guanethidine sulfate by desipramine hydrochloride

In five studies, the antihypertensive effect of guanethidine sulfate was significantly reversed by two antidepressants, desipramine hydrochloride and protriptyline hydrochloride. This reversal was not immediate, requiring many hours before maximum antagonism was seen. After discontinuation of desipramine, an average of five days was required for the antihypertensive action of guanethidine to reappear. Three similar studies demonstrated that the antihypertensive action of bethanidine sulfate, a guanethidine-related drug, was reversed by desipramine also. The reversal of bethanidine was more rapid than with guanethidine, with almost maximum antagonism appearing within four hours, while the delay in the reappearance of bethanidine's antihypertensive action was similar to that seen with guanethidine. A blockade by the antidepressants of the uptake of the antihypertensives to their active site within the sympathetic neuron is suggested as a mechanism for the antagonism.

Antagonism of the Antihypertensive Action of Guanethidine Sulfate by Desipramine Hydrochloride

In five studies, the antihypertensive effect of guanethidine sulfate was significantly reversed by two antidepressants, desipramine hydrochloride and protriptyline hydrochloride. This reversal was not immediate, requiring many hours before maximum antagonism was seen. After discontinuation of desipramine, an average of five days was required for the antihypertensive action of guanethidine to reappear. Three similar studies demonstrated that the antihypertensive action of bethanidine sulfate, a guanethidine-related drug, was reversed by desipramine also. The reversal of bethanidine was more rapid than with guanethidine, with almost maximum antagonism appearing within four hours, while the delay in the reappearance of bethanidine's antihypertensive action was similar to that seen with guanethidine. A blockade by the antidepressants of the uptake of the antihypertensives to their active site within the sympathetic neuron is suggested as a mechanism for the antagonism.

The Carbohydrate Nutrition of Tomato Roots

The addition of 0-01-0*015 per cent, galactose or 0-005-0-01 per cent, mannose reduces by 50 per cent, the linear growth of excised tomato roots cultured in a i per cent, sucrose medium. An addition of 0*03-0-04 per cent, of either sugar causes not less than a 90 per cent, inhibition of growth. The survival of meristematic activity is higher in presence of fully inhibitory concentrations of mannose than of galactose. Roots inhibited by galactose are distinguishable from those inhibited by mannose. The inhibitory effect of concentrations of galactose up to 0-15 per cent, and of mannose up to 0-4 per cent, can be fully antagonized by the simultaneous addition to the culture medium of dextrose. The minimum ratio of dextrose : inhibitory sugar for maximum antagonism of the growth inhibition is with galactose 5 : i and with mannose 3*5 : 1. Growth of roots in a dextrose-containing medium does not protect them from subsequent inhibition by either galactose or mannose. ?/-xylose has significant activity as an antagonist of mannose inhibition and even more so of galactose inhibition. However, the restoration of growth achievable from the addition of xylose is not comparable with that resulting from the addition of dextrose. The inhibition of growth by xylose is not alleviated by the simultaneous addition of dextrose. Maltose has low activity as an antagonist of galactose and mannose inhibition. All other sugars tested and the sugar alcohols corresponding to galactose and mannose were quite inactive as antagonists of the growth inhibition by these two sugars. Mixtures of partially inhibitory concentrations of galactose and mannose were less inhibitory than their more inhibitory component. The concentration of dextrose required to reverse the inhibitory activity of such mixtures was not greater than the minimum concentration required to antagonize the action of the more inhibitory component. The antagonism of galactose inhibition by dextrose is not due to dextrose impeding galactose uptake.

COMPARATIVE STUDIES ON RESPIRATION

1. Concentrations of La(NO(3))(3) up to 0.000025 M have little effect upon the rate of respiration of Bacillus subtilis; at 0.000006 M there is an increase in rate, while in higher concentrations there is a decrease in rate. 2. There is well marked antagonism between La(NO(3))(3) and NaCl, and very slight antagonism between La(NO(3))(3) and CaCl(2). 3. It requires a very small amount of La(NO(3))(3) to antagonize NaCl, the proportions of the two salts at their maximum antagonism being 99.8 parts of NaCl and 0.2 parts of La(NO(3))(3).