the lipopeptide molecules to produce a standardised and consistent biofungicide on a laboratory scale , which would be effective in a wide range of physical and chemical environments ,” says Prof . Clarke .
The study set out to :
• identify and quantify the key performance indicators for optimal antifungal lipopeptide production ;
• identify and quantify appropriate antifungal lipopeptide concentration and purification procedures ; and
• evaluate the effectiveness of different lipopeptides in various grades of purity on phytopathogens targeting the fruit industry .
Method
The team applied chemical engineering and life science principles to produce , extract , purify and fractionate a cocktail from Bacillus cultures that contained approximately 100 homologues of the lipopeptide families surfactin , iturin and fengycin .
Bacillus spp . culture in shake flasks .
Supernatant after centrifugation .
Precipitation of lipopeptides caused by adding acid .
Identify and quantify the key performance indicators for optimal antifungal lipopeptide production :
Firstly , a kinetic analysis was conducted to determine the parameters for producing the antifungal lipopeptides surfactin , iturin and fengycin from B . amyloliquefaciens under the most efficient conditions in both shake flasks and laboratory scale bioreactors .
The lipopeptide concentration , yield , productivity and selectivity with changes in oxygen , and nitrate and ammonia ratios and concentrations , were closely monitored .
Findings : The team determined the nitrate and ammonia ratio and concentration for optimal kinetics , in terms of lipopeptide concentration , yield , productivity and selectivity , during the production process . They also found that lipopeptide production is enhanced in the presence of oxygen .
LEARNING ABOUT LIPOPEPTIDES
Antimicrobial lipopeptides are natural antifungal agents found widely in nature . They kill various types of bacteria , fungi and viruses by drilling a hole in the membrane of the microbe and then inactivating and destroying the organism by disrupting transport across the membrane .
Because they primarily disrupt the cell membrane , they are effective against a broad spectrum of pathogenic microorganisms , with less probability of resistance .
Lipopeptide precipitate to be sent for separation and drying .
The antibiotic compounds released by Bacillus spp . are considered one of the most effective biological control mechanisms for plant pathogens . However , when the entire bacterial culture – which is a living organism – is applied directly , the successful release of the antibiotic compounds depends on near-perfect climatic conditions . Such dependency limits use on a commercial scale and prompted research into ways to extract the compounds and make them available without Nature ’ s intervention .
AgriKultuur | AgriCulture
42