Gypsum Biomineralization in Sulphide-rich Hardpans by a Native Trichoderma harzianum Rifai Strain

Natural acid mine drainage affects abandoned sulfide mines worldwide, causing hardpan formation and heavy metal leaching. Hardpans are characterized by very low permeability, thus representing a significant limiting factor for oxygen and water circulation in the rhizosphere. Our work shows the results concerning the gypsum biomineralization capability of a native Trichoderma harzianum Rifai strain in sulfide -rich hardpans. Two months after the fungal inoculum, hardpan clasts resulted, completely covered by T. harzianum mycelium, where newly formed gypsum crystals occur. Our study provided the first evidence about interaction between T. harzianum and sulfide -mineralized hardpans as well as about its influence on gypsum genesis.     

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

A combination of two compatible micro‐organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper. The population of the pathogen in soil was reduced by 75% as a result. Vegetative growth of the mycelium of P. capsici was inhibited in vitro on the second day after P. capsici and T. harzianum were placed on the opposite sides of the same Petri plate. Trichoderma harzianum was capable of not only arresting the spread of the pathogen from a distance, but also after invading the whole surface of the pathogen colony, sporulating over it. Scanning electron microscopy showed the hyphae of P. capsici surrounded by those of T. harzianum, their subsequent disintegration, and the eventual suppression of the pathogen's growth. Streptomyces rochei produced a zone of inhibition, from which was obtained a compound with antioomycete property secreted by the bacteria. When purified by high‐pressure liquid chromatography, this compound was identified as 1‐propanone, 1‐(4‐chlorophenyl), which seems to be one of the principal compounds involved in the antagonism. A formulation was prepared that maintained the compound's capacity to inhibit growth of the pathogen for up to 2 years when stored at room temperature in the laboratory on a mixture of plantation soil and vermiculite. The two antagonists, added as a compound formulation, were effective at pH from 3.5 to 5.6 at 23–30°C. The optimal dose of the antagonists in the compound formulation was 3.5 × 10⁸ spores/ml of T. harzianum and 1.0 × 10⁹ FCU/ml of S. rochei. This is the first report of a compound biocontrol formulation of these two antagonists with a potential to control root rot caused by P. capsici.     

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.     

A new xylanase from a Trichoderma harzianum strain

A new xylanase (XYL2) was purified from solid-state cultures of Trichoderma harzianum strain C by ultrafiltration and gel filtration. SDS-PAGE of the xylanase showed an apparent homogeneity and molecular weight of 18 kDa. It had the highest activity at pH 5.0 and 45°C and was stable at 50°C and pH 5.0 up to 4 h xylanase. XYL2 had a low K _m with insoluble oat spelt xylan as substrate. Compared to the amino acid composition of xylanases from Trichoderma spp, xylanase XYL2 presented a high content of glutamate/glutamine, phenylalanine and cysteine, and a low content of serine. Xylanase XYL2 improved the delignification and selectivity of unbleached hardwood kraft pulp. Received 02 February 1999/ Accepted in revised form 17 April 1999     

Germination of Cicer arietinum seeds and thiourea-induced phytotoxicity

Thiourea, hydroxyurea, phenylthiourea, methylurea, methylthiourea, thiosemicarbazide and 2,2-dithiodipyridine affected the germination of Cicer arietinum L. cv. Castellana (chick-pea) seeds. Microscopic observations of the subapical zone of the radicle showed that thiourea induced an increase in cell volume and length when compared with control seeds germinated at 25° or 30°C in water. These results emphasize the importance of the processes controlling solute and water uptake during early germination of chick-pea seeds. In contrast to this stimulation of volume increase, the thiourea-treated seedlings were unable to synthesize chlorophyll when exposed to light. This toxic effect was reduced when thiourea was administered only during the first few hours of germination. Thiourea also caused an increase in the uptake of ³H-thymidine and ¹⁴C-leucine but it decreased their incorporation into DNA and protein, respectively. These results suggest a stimulation of plasmalemma exchange activities, but toxic or inhibitory effects on other metabolic processes necessary for normal development of seedlings.     

花青素对神经退行性疾病保护作用的研究进展

对近年来花青素在神经退行性疾病中的研究进展进行综述,并从抑制氧化应激、缓解神经炎症、缓解兴奋性毒性和抑制蛋白异常聚集等方面对花青素的神经保护作用机制进行探讨,为进一步了解和研究花青素类化合物在神经退行性疾病中的预防作用提供科学依据。     

Cloning of a Cicer arietinum beta-galactosidase with pectin-degrading function

The cDNA clone (CanBGal-3) encoding a cell wall pectin-degrading beta-galactosidase (beta III-Gal) from Cicer arietinum L. cv. Castellana has been identified. The identification was carried out by comparing the deduced amino acid sequences of several isolated chickpea beta-galactosidase clones with the purified beta III-Gal protein sequence. The expression pattern of the gene corresponding to CanBGal-3 was in concordance with the fluctuations of the enzyme beta III-Gal in different seedling organs, being specific to elongating organs such as epicotyls and roots. Transformation of Solanum tuberosum plants with the chickpea CanBGal-3 clone indicated that the beta-galactosidase encoded by this clone is a pectin-degrading enzyme. The authors propose an important role for chickpea beta III-Gal in pectin degradation in cell walls of vegetative organs such as epicotyls and roots. The degradation of galactan carried out by this enzyme may determine structural changes and affect cell wall porosity. It is suggested that the increase in the size of cell wall pores could permit access of other cell wall-modifying enzymes to their substrate.     

Effect of Date of Sowing on the Incidence of Sclerotinia Stem Rot and Wilt of Gram (Cicer arietinum L.)

Gram (Cicer arietinum L.) was sown at different dates, viz., 15, 22, 29 Oct., 5, 12, 19 and 26 Nov., and 3 and 10 Dec. in 1978–1979 and 1979–1980 in four replications to enable observations to be made on the occurrence and severity of stem rot and wilt infection caused by Sclerotinia sclerotiorum (Lib.) de Bary. The plant height and canopy width were also measured and correlated with the disease intensity. Yield of each plot was taken as the criterion for suggesting to farmers the best period of sowing the gram crop. November was the most suitable period for this purpose.     

Cytostatic effect of L-lysine-alpha-oxidase from Trichoderma harzianum Rifai and Trichoderma viride

L-lysine-alpha-oxidase, a new fungal enzyme catalyzing oxidative L-lysine deamination, was shown to have an inhibitory effect on the in vitro synthesis of DNA, RNA and proteins in human carcinoma ovarian (CaOv) cells.     

A gene for leaf necrosis in chickpea (Cicer arietinum L.)

Necrosis of leaves was observed in the glabrous mutant (ICC 15566) of desi chickpea (Cicer arietinum L.). It was characterized by drying of leaflet margins to drying of complete leaflets of older leaves. The oldest leaves were the most affected and the intensity of necrosis decreased toward the apical meristem. A single recessive gene, designated nec, was found to govern the necrotic characteristic. The nec locus was linked to gl (glabrous shoots) with a map distance of 16 +/- 3 cM. The loci slv (simple leaves), mlv (multipinnate leaves), nlv (narrow leaflets), hg (prostrate growth habit), P (pink corolla), and shp (round seed shape) segregated independently of nec.     

Auxin regulated poly(A)polymerase activity in Cicer arietinum epicotyls

There was a linear increase in poly (A+) polymerase activity in the C. arietinum epicotyls during germination. Six-day-old auxin treated seedlings showed about 3-4 fold stimulation in enzyme activity, accompanied with 3- fold rise in the relative abundance of poly (A+) RNA levels. Actinomycin D, cycloheximide, cordycepin and amino acid analogues caused dramatic decline in poly (A+) polymerase as well as poly (A+) RNA levels. It seems that auxin induced a de novo synthesis of this enzyme.     

A trypsin and chymotrypsin inhibitor from chick peas (Cicer arietinum).

1. A trypsin and chymotrypsin inhibitor was isolated by extraction of chick-pea meal at pH8.3, followed by (NH4)2SO4 precipitation and successive column chromatography on CM-cellulose and calcium phosphate (hydroxyapatite). 2. The inhibitor was pure by polyacrylamide-gel and cellulose acetate electrophoresis and by isoelectric focusing in polyacrylamide gels. 3. The inhibitor had a molecular weight of approx. 10000 as determined by ultracentrifugation and by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. A molecular weight of 8300 was resolved from its amino acid composition. 4. The inhibitor formed complexes with trypsin and chymotrypsin at molar ratios of 1:1. 5. Limited proteolysis of the inhibitor with trypsin at pH3.75 resulted in hydrolysis of a single-Lys-X-bond and in consequent loss of 85% of the trypsin inhibitory activity and 60% of the chymotrypsin inhibitory activity. Limited proteolysis of the inhibitor with chymotrypsin at pH3.75 resulted in hydrolysis of a single-Tyr-X-bond and in consequent loss of 70% of the trypsin inhibitory activity and in complete loss of the chymotrypsin inhibitory activity. 6. Cleavage of the inhibitor with CNBr followed by pepsin and consequent separation of the products on a Bio Gel P-10 column, yielded two active fragments, A and B. Fragment A inhibited trypsin but not chymotrypsin, and fragment B inhibited chymotrypsin but not trypsin. The specific trypsin inhibitory activity, on a molar ratio, of fragment A was twice that of the native inhibitor, suggesting the unmasking of another trypsin inhibitory site as a result of the cleavage. On the other hand, the specific chymotrypsin inhibitory activity of fragment B was about one-half of that of the native inhibitor, indicating the occurrence of a possible conformational change.     

Characterization and applications of chitinases from Trichoderma harzianum– A review

Chitinases help degradation of cell walls containing chitin and thus accelerates protoplast formation. It indirectly helps strain improvement and development of new strains which are economically viable for industrial use. Chitinases consist of endochitinase, exochitinase, #-N-acetylglucosaminidases and chitobiases. The endochitinases can be further characterized for better understanding of mechanism of the enzyme reaction. This review covers the recent advances in isolation and characterization of endochitinases and its components, gene encoding sequences and cloning.     

A comparison between the cellulase systems of Trichoderma harzianum E58 and Trichoderma reesei C30

Summary Nearly all of the filter paper, endoglucanase and -glucosidase activities of T. harzianum E58 were located extracellularly, with low amounts of these activities detected in the cell extracts and relatively little associated with the cell wall. Most of the filter paper and endoglucanase activities of T. reesei C30 were detected extracellularly. The half lives of the different cellulase activities were assayed at various temperatures over a period of time. When the pH of the filtrate was adjusted to 4.8, the cellulase activities were considerably enhanced, with the average half-life at 50°C extended to 25 hrs. When various lignocellulosic substrates were hydrolyzed by T. harzianum E58 cellulases approximately 90% of the reducing sugars were present as glucose while 50–60% of the reducing sugars were detected as glucose when T. reesei C30 cellulases were used.     

Trichoderma harzianum cerato-platanin enhances hydrolysis of lignocellulosic materials

Considering its worldwide abundance, cellulose can be a suitable candidate to replace the fossil oil-based materials, even if its potential is still untapped, due to some scientific and technical gaps. This work offers new possibilities demonstrating for the first time the ability of a cerato-platanin, a small fungal protein, to valorize lignocellulosic Agri-food Wastes. Indeed, cerato-platanins can loosen cellulose rendering it more accessible to hydrolytic attack. The cerato-platanin ThCP from a marine strain of Trichoderma harzianum, characterized as an efficient biosurfactant protein, has proven able to efficiently pre-treat apple pomace, obtaining a sugar conversion yield of 65%. Moreover, when used in combination with a laccase enzyme, a notable increase in the sugar conversion yield was measured. Similar results were also obtained when other wastes, coffee silverskin and potato peel, were pre-treated. With respect to the widespread laccase pre-treatments, this new pre-treatment approach minimizes process time, increasing energy efficiency.