A method of batch-purifying microalgae with multiple antibiotics at extremely high concentrations

Abstract

A bs tractAxenic microalgal strains are highly valued in diverse microalgal studies and applications. Antibiotics, alone or in combination, are often used to avoid bacterial contamination during microalgal isolation and culture. In our preliminary trials, we found that many microalgae ceased growing in antibiotics at extremely high concentrations but could resume growth quickly when returned to an antibiotics-free liquid medium and formed colonies when spread on a solid medium. We developed a simple and highly effi cient method of obtaining axenic microalgal cultures based on this observation. First, microalgal strains of different species or strains were treated with a mixture of ampicillin, gentamycin sulfate, kanamycin, neomycin and streptomycin (each at a concentration of 600 mg/L) for 3 days; they were then transferred to antibiotics-free medium for 5 days; and fi nally they were spread on solid f/2 media to allow algal colonies to form. With this method, fi ve strains of Nannochloropsis sp. (Eustigmatophyceae), two strains of Cylindrotheca sp. (Bacillariophyceae), two strains of Tetraselmis sp. (Chlorodendrophyceae) and one strain of Amphikrikos sp. (Trebouxiophyceae) were purifi ed successfully. The method shows promise for batchpurifying microalgal cultures.

Effect of removal of bacteria on the biomass and extracellular carbohydrate productivity of Botryococcus braunii

“…To study the role or effects of bacteria present in microalgae cultures, it is necessary to remove them. Several approaches are commonly used such as centrifugation, washing and sieving methods, and the use of antibiotics (Bruckner and Kroth 2009;Lee et al 2015;Han et al 2016). Another method to remove bacteria commonly used in environmental technology, medical practices and the pharmaceutical industry is the use of UV (Schmidt and Kauling 2007;Carney and Lane 2014;Yen et al 2014).…”

Botryococcus braunii for the production of hydrocarbons and exopolysaccharides and the role of associated bacteria

“…Antibiotics that were applied individually were also successful in removing bacteria. For example, the addition of and Gen for the removal of bacteria from several microalgae cultures or aquatic environments (Lai et al 2009, D'Costa and Anil 2014, Han et al 2016.…”

“…cocktails (Joo and Lee 2007, Han et al 2016, Molina-Cardenas et al 2016. In this thesis a similar approach was used primarily to change the bacterial community present with B.…”

“…For instance, this can be achieved by using antibiotics (Joo and Lee 2007, Han et al 2016, Molina-Cardenas et al 2016. Antibiotics are small molecules made by microbes that serve as antagonistic agents to provide them a competitive advantage over other microbes (Clardy et al 2009).…”

“…Several approaches are commonly used such as, centrifugation, washing and sieving methods, and the use of antibiotics (Bruckner and Kroth 2009, Han et al 2016. Another method of sterilization commonly used in environmental technology, medical practices and pharmaceutical industry is the use of UV (Schmidt and Kauling 2007, Carney and Lane 2014, Yen et al 2014.…”