The study was aimed to quantify the Cr sorption ability of powdered biomass of
Rhizopus nigricans at the best operating conditions. The influence of solution pH, agitation, Cr (VI) concentration, ...biomass dosage, contact time, biomass particle size and temperature were studied. The optimum pH for biosorption of Cr (VI) was found to be 2.0. Higher adsorption percentage was noted at lower initial concentrations of Cr ions, while the adsorption capacity of the biomass increased with increasing concentration of ions. Optimum biomass dosage was observed as 0.5% (w/v). More than 75% of the ions were removed within 30 min of contact and maximum removal was obtained after 8 h. Biomass particles of smaller size (90 μm) gave maximum adsorption (99.2%) at 100 mg/l concentration. The adsorption capacity increased with increase in temperature and agitation speed and the optimum were determined as 45°C at 120 rpm. Freundlich and Langmuir isotherms were used to evaluate the data and the regression constants were derived. The adsorption rate constant values (
K
ad) were calculated for different initial concentration of Cr ions and the sorption was found to be higher at lower concentration (100 mg/l) of metal ion.
The information on airborne allergenic fungal flora in rural agricultural areas is largely lacking. Adequate information is not available to the bioaerosol researchers regarding the choice of single ...versus multiple sampling stations for the monitoring of both viable and non-viable airborne fungi. There is no long-term study estimating the ratios of viable and non-viable fungi in the air and earlier studies did not focus on the fractions of airborne allergenic fungi with respect to the total airborne fungal load. To fill these knowledge gaps, volumetric paired assessments of airborne viable and non-viable fungi were performed in five outdoor sampling stations during two consecutive years in a rural agricultural area of India. Samples were collected at 10-day intervals by the Burkard Personal Slide Sampler and the Andersen Two-Stage Viable Sampler. The data on the concentrations of total and individual fungal types from five stations and 2 different years were analyzed and compared by statistical methods. The allergenicity of the prevalent airborne viable fungi was estimated by the skin-prick tests of >100 rural allergy patients using the antigenic fungal extracts from isolates collected with the Andersen sampler. The ranges of total fungal spore concentration were 82–2365 spores per cubic meter of air (spores/m
3) in the first sampling year and 156–2022 spores/m
3 in the second sampling year. The concentration ranges of viable fungi were 72–1796 colony-forming units per cubic meter of air (CFU/m
3) in the first sampling year and 155–1256 CFU/m
3 in the second sampling year. No statistically significant difference was observed between the total spore data of the 2 years, however, the data between five stations showed a significant difference (
P<0.0001). No statistically significant difference existed between stations and years with respect to the concentration of viable fungi. When the data of individual allergenic fungal concentrations were compared between stations and years, no statistically significant difference was observed in all cases except for
Aspergillus japonicus and
Rhizopus nigricans, which showed significant difference in case of stations and years, respectively. The ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler from all sampling stations ranged between 0.29 and 7.61. The antigenic extracts of eight prevalent viable airborne fungi (
A. flavus,
A. japonicus,
A. fumigatus,
Alternaria alternata,
Cladosporium cladosporioides, Curvularia pallescens,
Fusarium roseum, and
R. nigricans) demonstrated >60% positive reactions in the skin prick test. These selected allergenic fungi collectively represented 31.7–63.2% of the total airborne viable fungi in different stations. The study concluded that: (i) a rich fungal airspora existed in the rural study area, (ii) to achieve representative information on the total airborne fungal spores of an area, the monitoring in multiple sampling stations is preferable over a single sampling station; for viable fungi, however, one station can be considered, (iii) the percentage of airborne fungal viability is higher in rural agricultural areas, and (iv) approximately 52% of the viable airborne fungi in the rural study area were allergenic.
► Overexpression of the tomato SlERF1 gene enhanced the resistance of tomato fruit to R. nigricans. ► A substantial transcript accumulation of PR1a, PR5, Chi1 and PAL genes was stimulated by ...overexpression of the SlERF1 gene. ► We found higher activities of phenylalanine ammonia lyase (PAL) and chitinase (CHI) in response to the fungal stress. ► Ethylene is involved in, but does not play the pivotal role, in fruit resistance to R. nigricans.
The tomato SlERF1 gene belongs to a distinct subfamily of the large ERF gene family. It is a downstream component in the ethylene signaling pathway in tomato, and is involved in plant defense and stress responses. Overexpression of the SlERF1 gene (SlERF1-OEs) in tomato dramatically enhanced the resistance of fruit to Rhizopus nigricans. In attempt to elucidate the mechanism basis of this observation, our study revealed a dual modulation. Firstly, SlERF1-OEs fruit showed a remarkable transcript accumulation of PR5 and PAL genes before infection with R. nigricans, which was not observed in wild-type (WT) fruit. Secondly, SlERF1-OEs fruit had higher activitiers of phenylalanine ammonia lyase (PAL) and chitinase (CHI) in response to the fungal stress. These results show that SlERF1 positively modulated the ethylene-dependent pathogenesis defense pathway in tomato. That may be one of the mechanisms by which ERFs enhance plant tolerance to fungal invasion.
A cDNA library from tobacco inoculated with Rhizoctonia solani was constructed, and several cDNA fragments were identified by differential hybridization screening. One cDNA clone that was ...dramatically repressed, NtKTI1, was confirmed as a member of the Kunitz plant proteinase inhibitor family. RT-PCR analysis revealed that NtKTI1 was constitutively expressed throughout the whole plant and preferentially expressed in the roots and stems. Furthermore, RT-PCR analysis showed that NtKTI1 expression was repressed after R. solani inoculation, mechanical wounding and salicylic acid treatment, but was unaffected by methyl jasmonate, abscisic acid and NaCl treatment. In vitro assays showed that NtKTI1 exerted prominent antifungal activity towards R. solani and moderate antifungal activity against Rhizopus nigricans and Phytophthora parasitica var. nicotianae. Bioassays of transgenic tobacco demonstrated that overexpression of NtKTI1 enhanced significantly the resistance of tobacco against R. solani, and the antisense lines exhibited higher susceptibility than control lines towards the phytopathogen. Taken together, these studies suggest that NtKTI1 may be a functional Kunitz trypsin inhibitor with antifungal activity against several important phytopathogens in the tobacco defense response.
Liposome-mediated transformation is common for cells with no cell wall, but has very limited usage in cells with walls, such as bacteria, fungi, and plants. In this study, we developed a procedure to ...introduce DNA into mycelium of filamentous fungi, Rhizopus nigricans LH 21 and Pleurotus ostreatus TD 300, by liposome-mediation but with no protoplast preparation. The DNA was transformed into R. nigricans via plasmid pEGFP-C1 and into P. ostreatus via 7.2 kb linear DNA. The mycelia were ground in 0.6 M mannitol without any grinding aids or glass powder for 15 min to make mycelial fragments suspension; the suspension was mixed with a mixture of the DNA and Lipofectamine 2000, and placed on ice for 30 min; 100 μL of the transformation solution was plated on potato dextrose agar (PDA) plate and cultivated at 28 °C for transformant screening. The plasmid and the linear DNA were confirmed to be integrated into the host chromosome, proving the success of transformation. The transformation efficiencies were similar to those of electroporation-mediated protoplast transformation (EMPT) of R. nigricans or PEG/CaCl2-mediated protoplast transformation (PMT) of P. ostreatus, respectively. The results showed that our procedure was effective, fast, and simple transformation method for filamentous fungi.
•We develop a novel procedure to introduce DNA into filamentous fungi.•The procedure is liposome-mediated mycelial rather than protoplast transformation.•Plasmid and long linear DNA are all effectually transformed by this procedure.•The procedure is fast and effective transformation method for filamentous fungi.
Recent data indicate that fungi may contribute to increased severity of asthma.
To determine the prevalence of allergy to 15 mold allergens among patients hospitalized because of exacerbation of ...asthma and to evaluate the relationship between the severity of the disease and allergy to particular molds.
Skin prick tests with standard aeroallergens of airborne allergens, including grass, tree, Dermatophagoides pteronyssinus, Dermatophagoides farinae, feather, and cat and dog fur, and a panel of mold allergens, including Alternaria, Cladosporium, Aspergillus, Penicillium, Trichothecium, Chaetomium globosum, Epicoccum, Epidermophyton, Helminthosporium, Aureobasidium pullulans, Rhizopus nigricans, Fusarium, Mucor, Merulius lacrymans, and yeast mix, were performed in 105 asthmatic patients and 30 controls.
Positive skin prick test results were found in 98% of asthmatic patients and 66% of controls. Sensitivity to A pullulans was significantly associated with more severe asthma (odds ratio, 1.4; 95% confidence interval, 1.09-1.75; P = .006). Sensitization to Helminthosporium was associated with an increased number of asthma exacerbations that required hospitalization (17% vs 38%; chi2 test P = .03).
Sensitization to A pullulans is a risk factor for severe asthma. Sensitization to Helminthosporium may be related to asthma exacerbation that requires hospitalization.
Chitin deacetylase is an enzyme, which catalyses the hydrolysis of
N-acetamido bonds of chitin, converting it to chitosan. In the present report we purified the chitin deacetylase from mycelial ...extracts of a zygomycete
Rhizopus nigricans by sequential ammonium sulfate precipitation, CM Sepharose chromatography and DEAE-cellulose chromatography. The progress of enzyme purification was followed by measurement of enzyme activity using partially
O-hydroxyethylated chitin (glycol chitin) radiolabelled in
N-acetyl groups as a substrate. The apparent molecular mass of chitin deacetylase obtained by SDS-PAGE was approximately 100
kDa. A cDNA library containing a chitin deacetylase gene from
R. nigricans was constructed and the complete gene was sequenced. The complete gene contains an open reading frame of 1341 nucleotides, which encodes a sequence of 447 amino acid residues. The estimated molecular mass is 47
kDa, suggesting that carbohydrate content is 53% by weight of the protein. The gene sequence consists of nucleotides encoding a conserved polysaccharide deacetylase domain located in the middle, covering 34% of the entire sequence. Overall, there were eight possible N-linked glycosylation sites. The deduced amino acid sequence shows the highest identity with chitin deacetylases from other zygomycetes
Phycomyces blakesleeanus,
Gongronella butleri,
Rhizopus oryzae and
Mucor rouxii (55%, 48%, 43% and 41% identity, respectively).
<正>Objective:To investigate the antioxidant,antimicrobial,antiplasmodial,acute toxicity and haemolytic activities of methanolic extracts of three plants.Phytochemical analysis to determine the ...phenolic contents was also carried out.Methods:The 2,2-diphenyl-1- picryl-hydrazyl（DPPH） free radical scavenging,NCCLS broth microdilution and Plasmodium Lactate Dehydrogenase（pLDH） assays were used to determine antioxidant,antimicrobial and antiplasmodial activities,respectively.Haemolysis assay was conducted on A+ human red blood cells and acute toxicity on male Swiss albino mice.Phenolics were quantitatively determined using spectrophotometric methods.Results:The DPPH assay yielded interesting antioxidant activities of methanolic extract of Parinari curatellifolia（P.curatellifolia） and Entada africana （E.africana）(IC50 were 0.20±0.01μg/mL and 0.47±0.01μg/mL,respectively).This activity was highly correlated with phenolic contents of extracts.The antimicrobial tests displayed minimal inhibitory concentrations（MICs） values ranging from 0.90 to 1.80 mg/mL for Serratia marcescens （5.marcescens） the most susceptible bacterial strain.MIC value was 1.20 mg/mL for susceptible fungal strains including Mucor rouxi（M.rouxi）,Fusarium oxyporum（F.oxyporum） and Rhizopus nigricans（R.nigricans）.pLDH assay showed moderate antiplasmodial activity of Balanites aegyptiaca（B.aegyptiaca）(IC50= 24.56±3.45μg/mL),however this extract was highly haemolytic and toxic in mice(LD50= 625±128mg/kg).Conclusions:Our results support in part the use of the selected plants in the treatment of microbial infections.In addition the plant showed interesting antioxidant activity that could be useful in the management of oxidative stress.
PDF
