ABSTRACT
Objective: To investigate the resource situation of endophytes in the roots of Panax ginseng (ginseng) of Jilin province and to select endophytes with antagonistic effect on pathogenic fungi of ginseng. Methods: Strains with antagonistic effect were screened by applying mixed strains method during preliminary screening and adopting antagonism method of fermentation liquor in re-screening. Besides, the selected endophytes were identified via 16S rDNA and ITS methods. Results: One hundred and thirty-three endophytes were isolated from ginseng. After preliminary screening and re-screening, four strains with good antagonistic effect on pathogenic fungi of ginseng were selected: B16, B25, B69, and F32. Among them, B16, B25, and B69 showed an inhibitory effect on six pathogenic fungi; F32 had a good inhibitory effect on Seclerotinia schinseng, Phytophthora cactorum, and Fusarium solani, with an inhibitory zone diameter of greater than 35 mm; According to the identification, B16, B25, B69, and F32 were Bacillus methylotrophicus, B. amyloliquefaciens, B. vallismortis, and Penicillium daleae, respectively. Conclusion: Endophytes in ginseng are diversified and there also exist strains with high antagonistic effect, which can be a good source for biocontrol bacterium and fungus of ginseng diseases.
ABSTRACT
Aims: To evaluate the possible in vitro interaction between methanolic extract of root of Adiantumcapillus-veneris and certain known antimicrobial drugs i.e. Oxacillin, Ceftazimide, Cefriaxone, Ofloxacin, Meropenem, Erythromycin, Cefuroxime, Cefoxitin, Cefotaxime and Ampicillin. Methodology and results: The study was carried out against ten bacterial strains (Staphylococcus aureus, S. epidermidis, Salmonella typhi, Klebsiella pneumoniea, Shigella dysentriea, Proteus vulgaris, Pseudomonas aeruginosa, Providencia species, Citrobacter freundii and Escherichia coli isolated from urine, pus and blood samples. Both disc diffusion and well diffusion methods were used to determine antimicrobial activity of plant extract in combination with antibiotics. Antimicrobial sensitivity showed that Meropenem was the most effective antibiotic with zone of inhibition (ZI) of 25-33 mm among all tested antibiotics followed by Ofloxacin (10-26.5 mm), Ceftriaxone (8-20 mm), while Oxacillin showed no activity against almost all bacterial strains. The study showed that most bacterial strains were resistant to most of the antibiotics used, ranging from 20-60%. The methanolic extract (mEXT) of A. capillus-veneris used alone was active against most of the bacterial isolates with maximum activity against E. coli with 16 mm ZI. The study also indicated that there was an increased activity in case of combination of mEXT with antibiotics. The combined effects of plant extract with antibiotics were synergistic against most of the bacterial strains. The mEXT showed maximum synergistic effect with Ceftazimide with ZI of 42 mm followed by Meropenem (40 mm) and Ceftriaxone (28 mm) against multidrug-resistant (MDR) bacterial strains. Conclusion, significance and impact of study: The data suggests that plant extract could be used as alternative to antibiotics. These results give scientific backing that combination between plant extract and antibiotics would be useful in fighting the emerging drug-resistant bacterial pathogens.
Subject(s)
Anti-Infective Agents , Plants, MedicinalABSTRACT
Objective To investigate whether ultrasonic coupling agent (UCA)can produce shielding or antago-nistic effect on iodine disinfectant for preoperative skin disinfection.Methods Shielding or antagonistic effect of UCA on iodine disinfectant were detected by laboratory carrier immersion killing test and on-the-spot skin disinfec-tion test.Results Antagonistic effect:after the mixing of iodophor with UCA,the average killing rate of iodophor containing available iodine 2 500mg/L and 625 mg/L to Staphylococcus aureus decreased from 100.00% to 99.67%-99.78% and 96.85 % - 98.25 %,respectively;the average killing rate to Escherichia coli decreased from 100.00% to 99.71 %-99.82% and 95 .93 %-98.56%,respectively.Shielding effect:after smearing with UCA, the average killing rate of iodophor and iodine tincture + alcohol to Escherichia coli decreased from 100.00% to 30.76% and 100.00% to 94.48%,respectively;the average killing rate to Staphylococcus aureus decreased from 99.99% to 55 .55 % and 100.00% to 98.22%,respectively.On-the-spot skin disinfection test:the killing rate of io-dophor and iodine tincture +alcohol to natural bacteria on skin surface were both 99.99%,after skin was smeared with UCA,the killing rate decreased to 92.62% and 93 .57%,respectively.Conclusion UCA remained on the oper-ative field has shielding and antagonistic effect on iodine disinfectant.
ABSTRACT
Aims: The main objective of the present study was to investigate the larvicidal effect of some biological control agents like Beauveria bassiana and Bacillus thuringiensis var. israelensis (B.t.i.) and some natural control agents as Diflubenzuron, Azadirachtin and Emamectin benzoate on Culex pipiens mosquito. The toxicity of binary mixtures of these control agents was also assessed. Methodology: The larval susceptibility test of C. pipiens was estimated when the third instar were treated with Azadirachtin, B. bassiana, B.t.i., Diflubenzuron, Emamectin benzoate and Deltamethrin (reference compound). Series of concentrations for each compound in addition to control were replicated four times. Mortality counts were carried out after 24, 48 and 72hr of treatment. To determine the joint toxic action of the tested compounds, the calculated LC12.5, LC25 and LC50 (after 72hr) were used alone (to calculate the expected mortalities) and in bi-mixtures. For each treatment, four replicates of 30 larvae/replicate were used. Percent mortalities of larvae were recorded after 72hr post- treatment. The joint action of different mixtures in terms of co-toxicity factor (C.F.) was estimated. Data of bioassay were analyzed using Probit program. Results: Data showed that the LC50 of B.t.i., Emamectin benzoate, Azadirachtin, Diflubenzuron and B. bassiana were 0.044ppm, 1.24ppm, 3.02ppm, 10.32ppm and 4.122ml/L, respectively on the third instar of C. pipiens after 24hrs. Azadirachtin showed time related larvicidal activity. Diflubenzuron induced delayed effect on C. pipiens larvae. B. bassiana, had the lowest activity against this mosquitoes (LC50= 1.85ml/L) after 72hr of exposure. Data of joint toxic action of some mixtures such as (B. bassiana + Diflubenzuron) or (Diflubenzuron+Azadirachtin) revealed antagonistic effect while almost other binary mixtures showed potentiating effects. The mixture of LC12.5 B.t.i. + LC12.5 Deltamethrin recorded the highest potentiating activity. Conclusion: The study suggests that, the most effective tools for C. pipiens larvae eradication included B.t.i. followed by Emamectin benzoate, Azadirachtin, Diflubenzuron then B. bassiana. The use of some binary mixtures of these tested control measures can get better control, save the amount and reduce control cost.
ABSTRACT
Twenty isolates of Bacillus species obtained from livestock manure composts and cotton-waste composts were tested for their antagonistic effects in vitro against three green mold pathogens of mushrooms (Trichoderma harzianum, T. koningii, and T. viridescens). However, there exists a possibility Bacillus species may have antagonistic effects against mushrooms themselves, and thus the same 20 isolates were tested in vitro against three species of mushrooms (Flammulina velutipes, Lentinus edodes, and Pleurotus ostreatus). Of the 20 Bacillus species isolates tested, two inhibited mycelial growth of T. harzianum, seven that of T. koningii, and eight that of T. viridescens. Importantly, the bacterial isolates M27 and RM29 strongly inhibited mycelial growth of all the Trichoderma spp. isolates tested. The isolate M27 was subsequently identified as the most effective in inhibiting mycelial growth of all the Trichoderma species. Interesting results of the effect Bacillus isolates had upon the mushroom species followed. It was found that most Bacillus isolates except 5T33 at least somewhat inhibited mycelial growth of the three mushroom species or some of the mushrooms. Furhermore, the antagonistic effects of the bacterial isolates against the three species of mushrooms varied depending on the mushroom species, suggesting a role for mushroom type in the mechanism of inhibition. The bacterial isolates M27 and RM29 were identified as having the most antagonistic activity, inhibiting mycelial growth of all the Trichoderma spp. as well as mycelial growth of the three species of mushrooms. These results suggest that the bacterial isolates and their antagonistic effects on green mold pathogens should be further studied for their practical use for biological control of green mold in the growing room of the mushrooms.