Applying antagonistic yeasts is one of the recent possibilities for controlling postharvest disease caused by blue mould (Penicillium expansum). In this work, antagonistic activity of several Kl. lactisstrains was tested against two strains of P. expansum. Three strains of Kl. lactiswere compared to three biocontrol yeasts: Metschnikowia pulcherrima, Sporobolomyces roseusand Pichia anomala. The investigations were carried out at 25 °C, 15 °C and 5 °C, applying different yeast cell densities and culture media. Statistical analysis showed no significant differences among the three Kl. lactisstrains. The inhibitory effect of the tested yeasts was different according to the applied mould strain temperature, culture medium and cell density. Application of antagonistic yeasts combined with reduced temperature enhanced the inhibitory effect. Direct relationship was observed between increasing cell density and the biocontrol efficiency of Kl. lactis. According to this work, Kl. lactisis a possible biocontrol agent.
The antagonistic effect of thirteen
thirteen strains of other
species was studied on the
fungi. The inhibition of pathogen colony
growth was tested with two different
techniques using the same
type of culture media. In case of the spread slant technique the antagonists
induced a significantly stronger inhibition on the growth of pathogens than in
case of spot transfer. Among the 26 investigated
strains were generally more effective against the fungal
proved to be affected to a greater extent
by the bacterial strains studied than the
The possibility of
selection of biocontrol microbes is being further discussed
Numerous yeasts are reported as being effective in controlling plant pathogenic moulds. By selecting new biocontrol agents, knowledge about the mode of action of mould inhibition is important. In our study, mode of action of Kluyveromyces lactis - successfully applied against Penicillium expansum in former studies - was investigated. According to the results, volatile compounds are supposed to play a role in restriction of mould growth. Antibiotic substances and killer toxins produced by the tested Kl. lactis strain were not detected.
Eighteen isolates of fluorescent pseudomonads ad
spp. were isolated from the
suppressive soils of tomato fields. These isolates were evaluated in the laboratory and green house for the biocontrol of
. Eight isolates were considered to have potential for the biocontrol of
on the basis of the antibiotic sensitivity, fluorescence produced by
, inhibitory effect on the hatching and penetration of
and root colonization of tomato root by these isolates. These 8 isolates (Pa22, Pf25, Pf27, Pa28, B22, B23, B27 and B28) were further tested for their biocontrol potential against
on tomato in a pot test. Out of 8 isolates, isolate B28 was the best in improving tomato growth of
inoculated plants. Isolate B28 also caused greater reductions in galling and multiplication of
on tomato while isolate Pa28 was found best in improving growth of plants without
In this study, bacterial biocontrol agents against the phytopathogen Lasiodiplodia theobromae were screened from Thua Nao, a Thai fermented soybean product. A total of 170 bacterial strains were isolated and initially screened for their antagonistic activity by dual culture test. Of these, 39 isolates were able to inhibit the fungal growth showing the percentage of inhibition ranging from 25.0–67.5. Among them, the isolate TN79 was selected as a potential antagonistic strain for further study. For this, the bacterial strain TN79 was cultured on nutrient agar for 2 weeks and its crude extracts were prepared using phosphate buffÍer pH 7.0. The bacterial crude extracts prepared were active and could inhibit all four fungal strains of L. theobromae. The optimum pH for antifungal activity of the extracts was 7. In addition, the extracts were also active when exposed to the UV light (254 nm) up to 1 hour and to proteinase K treatment (1 mg/ml). The bacterial strain TN79 was then characterized in terms of their phenotypic and genotypic properties including morphology, biochemical profiles, and rRNA gene sequence. Based on this analysis, the bacterium TN79 was closely related to Bacillus velezensis.
Six potential isolates of
(out of 20 isolates screened under green house assay) were evaluated under pot and field conditions for the biocontrol of wilt disease complex of pigeonpea caused by
Heterodera cajani, Meloidogyne
. Isolate Pa324 was found best for the biocontrol of wilt disease complex of pigeonpea followed by B18, Pf18, Pa70, Pa116 and B160 under pot condition. Isolate Pa324 caused greater reduction in multiplication of
and also reduced wilting caused by
. Isolate Pa324 produced greater amount of siderophores followed by Pf18, Pa70 and Pa116. Isolate Pa324 showed greater hydrogen cyanide and indole acetic productions than other isolates. Moreover, seedling growth was higher when seeds were treated with Pf18 followed by Pa324, Pa116, B160 and B18. Isolate Pf18 caused a similar increase in seedling growth as was caused by Pa70. Under field condition too isolate Pa324 was best in reducing wilt disease complex followed by B18. Combined use of Pa324 with B18 provided better biocontrol of wilt disease complex than the use of either of them. Application of these isolates (Pa324 and B18) with
sp. caused about 30% increase in yield under field condition and provided substantial protection against wilt disease complex of pigeonpea.
Isolates of Pestalozzia theae Saw. and Trichoderma spp. were collected from Bangladesh Tea Research Institute (BTRI) farm area, Bangladesh. The cultural morphology and antagonistic potentiality of Trichoderma spp. against grey blight pathogen Pestalozzia theae was studied for tea cultivation. The antagonistic potentiality of Trichoderma spp., against Pestalozzia theae showed maximum (inhibition 84.45±0.77%) after 72 hrs of inoculation under in vitro condition followed by 76.02±3.50% after 24 hrs of inoculation. This study revealed that Trichoderma strain was highly effective to control Pestalozzia theae, the causal agent of grey blight disease of tea.