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Mosquitocidal Bacillus amyloliquefaciens: dynamics of growth & production of novel pupicidal biosurfactant.

Geetha I, Aruna R, Manonmani AM - Indian J. Med. Res. (2014)

Bottom Line: The pupal stages of mosquitoes were found to be more vulnerable to the biosurfactant produced by this bacterium with Anopheles stephensi being the most vulnerable species.The median lethal time (LT 50 ) was found to be 1.23 h when the pupal stages of the above species were exposed to lethal concentration LC 90 (9 µg/ml) dosage of the biosurfactant.Production of biosurfactant was found to increase with incubation time and maximum biomass, maximum quantity of biosurfactant (7.9 mg/ml), maximum biosurfactant activity (6 kBS unit/mg) and maximum mosquitocidal activity (5 µg/ml) were attained by 72 h of growth.

View Article: PubMed Central - PubMed

Affiliation: Vector Control Research Centre, Puducherry, India.

ABSTRACT

Background & objectives: A strain of Bacillus amyloliquefaciens (VCRC B483) producing mosquito larvicidal and pupicidal biosurfactant was isolated from mangrove forest soil. The present study was aimed at studying the kinetics of growth and production of the mosquitocidal biosurfactant by this bacterium.

Methods: Dynamics of growth, sporulation and production of mosquitocidal biosurfactant were studied by standard microbiological methods. The mosquitocidal biosurfactant was precipitated from the culture supernatant and bioassayed against immature stages of mosquito vectors to determine lethal dose and lethal time. The activity, biological and biochemical properties of the biosurfactant have also been studied.

Results: The pupal stages of mosquitoes were found to be more vulnerable to the biosurfactant produced by this bacterium with Anopheles stephensi being the most vulnerable species. The median lethal time (LT 50 ) was found to be 1.23 h when the pupal stages of the above species were exposed to lethal concentration LC 90 (9 µg/ml) dosage of the biosurfactant. Production of biosurfactant was found to increase with incubation time and maximum biomass, maximum quantity of biosurfactant (7.9 mg/ml), maximum biosurfactant activity (6 kBS unit/mg) and maximum mosquitocidal activity (5 µg/ml) were attained by 72 h of growth. The lipopeptide nature of the biosurfactant was confirmed by β-haemolysis, lipase activity, biofilm forming capacity, thermostability and biochemical analysis.

Interpretation & conclusions: The mosquitocidal biosurfactant produced by B. amyloliquefaciens (VCRC B483) may be a prospective alternative molecule for use in mosquito control programmes involving bacterial biopesticides.

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Determination of biosurfactant activity of CMB produced by B. amyloliquefaciens by oil displacement method.
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Figure 5: Determination of biosurfactant activity of CMB produced by B. amyloliquefaciens by oil displacement method.

Mentions: Determination of biosurfactant activity: Biosurfactant activity was studied at different hours by oil displacement test (Fig. 5). The production of biosurfactant was found to increase with the growth of the organism and maximum activity was observed with 72 h culture, i.e. 6000 BS (BioSurfactant) or 6 kBS unit/mg and this value was almost maintained till 144 h of incubation. The activity of biosurfactant coincided with the time of maximum production. There was a significant (P<0.002) correlation between logarithm of time and oil displacement activity and it was logarithmically linearly related with log incubation time [R2 = 0.87; Intercept (95% CI): -3.15 (-6.5, 0.24); Slope (95% CI): 1.89 (1.07, 2.7)].


Mosquitocidal Bacillus amyloliquefaciens: dynamics of growth & production of novel pupicidal biosurfactant.

Geetha I, Aruna R, Manonmani AM - Indian J. Med. Res. (2014)

Determination of biosurfactant activity of CMB produced by B. amyloliquefaciens by oil displacement method.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4248391&req=5

Figure 5: Determination of biosurfactant activity of CMB produced by B. amyloliquefaciens by oil displacement method.
Mentions: Determination of biosurfactant activity: Biosurfactant activity was studied at different hours by oil displacement test (Fig. 5). The production of biosurfactant was found to increase with the growth of the organism and maximum activity was observed with 72 h culture, i.e. 6000 BS (BioSurfactant) or 6 kBS unit/mg and this value was almost maintained till 144 h of incubation. The activity of biosurfactant coincided with the time of maximum production. There was a significant (P<0.002) correlation between logarithm of time and oil displacement activity and it was logarithmically linearly related with log incubation time [R2 = 0.87; Intercept (95% CI): -3.15 (-6.5, 0.24); Slope (95% CI): 1.89 (1.07, 2.7)].

Bottom Line: The pupal stages of mosquitoes were found to be more vulnerable to the biosurfactant produced by this bacterium with Anopheles stephensi being the most vulnerable species.The median lethal time (LT 50 ) was found to be 1.23 h when the pupal stages of the above species were exposed to lethal concentration LC 90 (9 µg/ml) dosage of the biosurfactant.Production of biosurfactant was found to increase with incubation time and maximum biomass, maximum quantity of biosurfactant (7.9 mg/ml), maximum biosurfactant activity (6 kBS unit/mg) and maximum mosquitocidal activity (5 µg/ml) were attained by 72 h of growth.

View Article: PubMed Central - PubMed

Affiliation: Vector Control Research Centre, Puducherry, India.

ABSTRACT

Background & objectives: A strain of Bacillus amyloliquefaciens (VCRC B483) producing mosquito larvicidal and pupicidal biosurfactant was isolated from mangrove forest soil. The present study was aimed at studying the kinetics of growth and production of the mosquitocidal biosurfactant by this bacterium.

Methods: Dynamics of growth, sporulation and production of mosquitocidal biosurfactant were studied by standard microbiological methods. The mosquitocidal biosurfactant was precipitated from the culture supernatant and bioassayed against immature stages of mosquito vectors to determine lethal dose and lethal time. The activity, biological and biochemical properties of the biosurfactant have also been studied.

Results: The pupal stages of mosquitoes were found to be more vulnerable to the biosurfactant produced by this bacterium with Anopheles stephensi being the most vulnerable species. The median lethal time (LT 50 ) was found to be 1.23 h when the pupal stages of the above species were exposed to lethal concentration LC 90 (9 µg/ml) dosage of the biosurfactant. Production of biosurfactant was found to increase with incubation time and maximum biomass, maximum quantity of biosurfactant (7.9 mg/ml), maximum biosurfactant activity (6 kBS unit/mg) and maximum mosquitocidal activity (5 µg/ml) were attained by 72 h of growth. The lipopeptide nature of the biosurfactant was confirmed by β-haemolysis, lipase activity, biofilm forming capacity, thermostability and biochemical analysis.

Interpretation & conclusions: The mosquitocidal biosurfactant produced by B. amyloliquefaciens (VCRC B483) may be a prospective alternative molecule for use in mosquito control programmes involving bacterial biopesticides.

Show MeSH
Related in: MedlinePlus