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Effect of crude ethanolic extracts from bottle brush (Callistemon viminalis) against leaf spot fungi and their phytotoxicity on lettuce (lactuca sativa l.)
(2020-01-01)
Somnuek, Suriyasit
;
Jaenaksorn, Tanimnun
;
Laosinwattana, Chamroon
In response to the public concern about environmental problems as well as fungicide residues on agricultural produces especially leaf vegetables, we investigated the potential use of crude extracts from bottle brush (C. viminalis) leaves against leaf spot fungi and their phytotoxicity on lettuce grown in hydroponics. Yield, total phenolic and flavonoid contents of the extract were also evaluated. Regarding the in vitro antifungal assay using poisoned food technique, 3×3 factorial in Completely Randomized Design (CRD) was employed with three replicates. Factor A was 3 crude extracts (50% ethanol, 70% ethanol and 95% ethanol crude extract) while factor B was the 3 concentrations (0, 5,000 and 50,000 ppm) of crude extracts. Results showed that all three crude extracts were significantly effective in inhibiting the mycelial growth and sporulation of leaf spot fungi (Alternaria sp. and Curvalaria sp.). There was a significant interaction between all extracts and their concentration regarding inhibition percent. Increase in crude extract concentrations resulted in a marked increase in their inhibition. The 50,000 ppm gave the highest effectiveness. For phytotoxicity test, all tested crude extracts did not give any negative effects either on seed germination or growth of lettuce grown in hydroponics. Interestingly, growth promotion about 30 percent was achieved on this regard. Based on quantitative assay, the highest yield of crude extract was obtained from 95% ethanol solvent. Highest total phenolic and flavonoid contents were detected at the highest concentration of all crude extracts.
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Impact of Asian bullfrog (Rana tigerina) skin oil on growth inhibition of colletotrichum gloeosporioides (in vitro) and its prediction modeling
(2020-01-01)
Kingwascharapong, Passakorn
;
Karnjanapratum, Supatra
;
Tanaka, Fumina
;
Tanaka, Fumihiko
The effect of Asian Bullfrog (Rana tigerina) skin oil on the mycelium growth of pathogenic fungi, Colletotrichum gloeosporioides, was studied in vitro. A poisoned substrate technique method (dilution in solid media) was employed to evaluate the antifungal activity of the frog skin oil (FSO) at different concentrations (0-10 %) against C. gloeosporioides. FSO showed an inhibitory effect, and the efficacy increased with increasing FSO concentration. A modified logistic model was applied to evaluate the antifungal activity of FSO at different concentrations. The modified logistic model showed a good agreement with the observed growth data for C. gloeosporioides. It can be concluded that FSO could potentially control the growth of C. gloeosporioides and that the modified logistic model could describe the inhibitory pattern of FSO against C. gloeosporioides effectively.
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GC-MS analysis and biopesticide properties of different crude extracts of Annona squamosa and Annona muricata
(2019-01-01)
Deewatthanawong, R.
;
Kongchinda, P.
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Deewatthanawong, P.
;
Pumnuan, J.
;
Insung, A.
Most common compounds identified by GC-MS analysis of ethanolic extracts from leaves of Annona squamosa (sweetsop) and Annona muricata (soursop) were neophytadiene, hexadecanoic acid, and trans-caryophyllene. Hexadecenoic acid and ethyl oleate were identified in seeds of A. muricata, while only methyl-p-tert-butyl phenylacetate was identified in seeds extract of A. squamosa. Crude extracts were tested for their antifungal activities against postharvest plant pathogens, insecticidal activities against brown planthopper, Nilaparvata lugens (Stål) and cassava mealybug, Phenacoccus manihoti Matile-Ferrero. Results showed low inhibitory effect (less than 20%) for the pathogenic fungi insecticidal test against cassava mealybug of all crude brown planthopper treated with 5% seed extract of A. squamosa, indicating its potential as an alternative botanical insecticide. Further studies are required to improve yield and extract quality.
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Production of propionic acid for antifungal activity by calcium alginate immobilization of Propionibacterium acidipropionici TISTR 442 using whey as substrate
(2011-07-01)
Choojun, Sukjai
;
Yoonprayong, Pornwisa
The improvement of propionic acid production, as fermenting by calcium alginate immobilized cells of Propionibacterium acidipropionici TISTR 442 and using whey as substrate was investigated. The highest amount of propionic acid was produced by adjusting the distance between the tip of the tube and the surface of CaCl<inf>2</inf> solution to be 4 - 6 cm and the flow rate of the gel solution to be 7 ml/min. Fermentation by immobilized cells in 2-l fermentors using1% CaCO<inf>3</inf> and 5 N KOH to control the pH at 6.5 gave the highest amount of propionic acid 29.24 g/l and consistent potential to recycle 2 rounds of fermentation by producing the total amount of 15.85±0.25 g/l and 13.39±0.25 g/l propionic acid from Batch 1 and Batch 2 fermentation, respectively. Which one amount of propionic acid was higher than that from free cells in 2-l fermentors at 216 h of the fermentation time. The fermented propionic acid as well as the commercial propionic acid from chemical processes were able to inhibit the growth of the fungal tested.

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