Selection of an actinobacteria mixed culture for chlordane remediation. Pesticide effects on microbial morphology and bioemulsifier production

Abstract

Chlordane bioremediation using actinobacteria mixed culture is an attractive clean-up technique. Their ability to produce bioemulsifiers could increase the bioavailability of this pesticide. In order to select a defined actinobacteria mixed culture for chlordane remediation, compatibility assays were performed among six Streptomyces strains. The strains did not show growth inhibition, and they were assayed for chlordane removal, either as pure or as mixed cultures. In pure cultures, all of the strains showed specific dechlorination activity (1.42-24.20 EU mg(-1)) and chlordane removal abilities (91.3-95.5%). The specific dechlorination activity was mainly improved with cultures of three or four microorganisms. The mixed culture consisting of Streptomyces sp. A2-A5-A13 was selected. Their ability to produce bioemulsifiers in the presence of glucose or chlordane was tested, but no significant differences were observed (p > 0.05). However, the stability of the emulsions formed was linked to the carbon source used. Only in chlordane presence the emulsions retained 100% of their initial height. Finally, the selected consortium showed a high degree of sporulation in the pesticide presence. This is the first study on the effects that chlordane exerts on microbe morphology and emulsifier production for a defined mixed culture of Streptomyces with ability to remediate the pesticide.

Bioelectrochemical and Conventional Bioremediation of Environmental Pollutants

“…The PD was increased 12.7% during a period of continued illumination; however, extended periods of illumination decreased the lifespan of the algae, which would suggest the need for a more intermittent illumination period. In comparison to an abiotic cathode, the PD of the biocathode was nearly 2.8 times greater [178].…”

“…However, under night (dark) conditions, there can be a substantial drop off in power generation. In a modified MFC using C. vulgaris at the cathode to generate oxygen, the algal cathode side had increased levels of dissolved oxygen and voltage during periods of illumination, while there was a decrease in both during the absence of illumination [178]. The PD was increased 12.7% during a period of continued illumination; however, extended periods of illumination decreased the lifespan of the algae, which would suggest the need for a more intermittent illumination period.…”

“…Cultivation of oxygenic phototrophs, such as algae or cyanobacteria, can provide a potential solution for overcoming O 2 limitation at the cathode during daylight. Microbial phototrophs are the source of 75% of the Earth's oxygen, which occurs perpetually if there is accessibility to light to photolyse water and utilize CO 2 from the environment to carry out photosynthesis [178]. Algae may be favorable over plants in that they have a short harvest cycle (1-10 days) [179].…”

“…Macrophytes are composed of polysaccharides, unsaturated fatty acids, and cellulose [180]. Chlorella vulgaris is a phytoplankton composed of greater than 50% protein and is one of the fastest growing of the microalgae phytoplankton [178]. C. vulgaris facilitates uptake of electrons from BES cathodes while reducing CO 2 to biomass [181].…”

Lindane dissipation in a biomixture: Effect of soil properties and bioaugmentation

“…The bioaugmentation of biopurification systems with pesticide-degrading microorganisms represents a very interesting approach in the design and optimization of these systems (Ruiz-Hidalgo et al, 2016). Among a variety of microorganisms known to degrade or mineralize pesticides, actinobacteria, especially those belonging to the Streptomyces genus, stand out as they have a great capacity to degrade various pesticides such as lindane, chlordane, methoxychlor, chlorpyrifos, diuron, diazinon and pentachlorophenol (Alvarez et al, 2017;Benimeli et al, 2008;Briceño et al, 2016Briceño et al, , 2012Fuentes et al, 2016Fuentes et al, , 2014. On the other hand, given that a half of the biomixture consists of lignocellulosic substrates, the bioaugmentation with ligninolytic fungi is of particular interest to potentially increase the degrading capacity of the biomixture.…”