41 research outputs found
Selection of antagonistic bean rhizosphere bacteria for the biological control of bean diseases caused by bacteria and fungi
Phyotochemical Properties of Acalypha indica (L), and its Antimicrobial Potential against Human Pathogens
The present work has been investigated for important medicinal properties of Acalypha indica (L).
A. indica crude extract was obtained, significant phytochemicals and antibacterial activity substance
for the control of numerous antibiotic resistance bacteria such as Escherichia coli, Salmonella typhi,
Staphylococcus epidermidis, Bacillus cereus, Staphylococcus marcescens, Staphylococcus aureus,
Streptococcus agalactiae, Streptococcus pyogenes and Streptococcus dysgalactiae. Antibacterial activity
of A. indica was performed using the crude extract on Muller- Hinton agar with and without 5% sheep
blood by the well diffusion method. We found Ethanol is the most favorable solvent for maximum
amount of A. indica extract followed by Acetone, however acetone has more antimicrobial activity.
Furthermore, we found Benzene and Diethyl ether are low yielding solvent for A. indica extract. A.
indica extract on antimicrobial activity showed remarkable activity in S. typhi, B. cereus followed by S.
epidermidis. Eight, phytochemicals tested in A. indica extract showed the existence of tannin, saponin,
alkaloid, flavonoid and phenol. Petroleum ether and ethyl acetate solvent (4.2:0.8), was most optimum
for the separation of more compounds by TLC analysis. In A. indica four major spots were detected,
of these, two major spots were scrabbled from the TLC plates and checked for antimicrobial activity
against B. cereus pathogen. B. cereus was selected based on our preliminary results, which showed
significant activity among other pathogens
Plant Defence Related Enzymes in Rice (Oryzae sativa L.,) Induced by Pseudomonas sp VSMKU2
In recent days, antibiotic producing fluorescent pseudomonads (FPs) has been used as a bioorganic tool for the control of sheath blight disease of rice. Combined application of antagonistic microorganism showed that significant bio control activity and enhances plant growth by induced systemic resistance (ISR). The present study, we carryout morphological, physiological and biochemical analysis and then identified, the selected isolate VSMKU2 is Pseudomonas sp. Maximum level of phenylalanine ammonia lyase (PAL) was quantified in the treatment of Pseudomonas sp VSMKU2 + R. solani on the 7th day (97.50 nmol trans-cinnamic acid/min/g). Similarly, the cell free culture filtrate of VSMKU2 challenged with R. solani demonstrated lower level of PAL activity on 7th day (91.76 nmol trans-cinnamic acid/min/g) compared to control. Peroxidase (PO) and polyphenoloxidase (PPO) gave higher activity in Pseudomonas sp VSMKU2 challenged with R. solani on 7th day (0.94 and 0.95 unit/min/g of proteinrespectively) but 14th and 21st day after challenged inoculation of R. solani had been reduced (0.92, 0.75 and 0.82, 0.65 unit/min/g of protein) compared to control. The total phenol content activity was significantly increased with Pseudomonas sp VSMKU2 (148.27 µg catechol/mg/g of protein) and cell free culture filtrate of VSMKU2 (137 µg catechol/mg/g of protein) treated in rice seedlings on 7th day after challenged inoculation of R. solani compared to control. The results obtained in the current study imply to Pseudomonas sp VSMKU2 was able to rise defence response, thereby contribute resistance to sheath blight disease
Preliminary results on the antagonistic activity of bean rhizosphere bacteria toward common bean pathogenic bacteria and fungi
Antibacterial activity of Components of Essential Oils and Their Potential Use in Seeds Disinfection
Among the main (g0.7%) components of some essential oils, considerable antibacterial activity was
shown by terpenoid and phenylpropanoid derivatives containing phenol and alcohol functionalities. A
reduced or no activity was shown by those derivatives containing ketones, aldehydes, ethers, and
ester functionalities as well as the remaining terpenoids. Eugenol emulsion treatments (1-8 mg/mL)
of bean seeds bearing about 2.6106 cfu/seed of strain ICMP239 of Xanthomonas campestris pv.
phaseoli var. fuscans determined a highly significant reduction of the bacteria on seeds. In
particular, eugenol at 4 mg/mL disinfect seeds bearing about 7.0102 cfu/seed and lower densities.
However, after 72 h, incubation treatments with 2, 4, and 8 mg/mL of eugenol caused germination
reduction of 3%, 7%, and 16%, respectively, which was significantly different from the controls. No
effect on germination was observed with 1 mg/mL eugenol emulsion treatment. These data indicate
eugenol as potentially useful for bean seed disinfection from X. campestris pv. phaseoli var.
fuscans. Further studies on the effects on seed vitality and on formulation of essential oils are
needed
Optimization of cultural conditions for production of chitinase by Bacillus laterosporous MML2270 isolated from rice rhizosphere soil
A total of 39 chitinolytic bacteria were isolated from 77 rhizosphere soil samples collected from different crop fields in Tamil Nadu state, India. Among them, a strain designated as MML2270, which produced highest chitinolytic activity in primary and secondary screening in colloidal chitin agar was selected and later identified as Bacillus laterosporous. The production of chitinase by B. laterosporous was optimized using different growth media, substrate concentrations, pH, temperature and incubationperiod. The maximum chitinase production was observed in yeast nitrogen based medium (YNB) amended with 0.3% colloidal chitin at pH 8.0 and 35°C after four days of inoculation. Under this optimized growth condition, B. laterosporous MML2270 produced a total chitinase activity of 59.05units/ml as against only 19.7 units/ml in the initial YNB medium stage, which is a three-fold increase