Application of micro-segmented flow for two-dimensional characterization of the combinatorial effect of zinc and copper ions on metal-tolerant Streptomyces strains

Abstract

The cultivation and growth behavior of metal-tolerant strains of Streptomyce acidiscabies E13 and Streptomyces sp. F4 were studied under droplet-based microfluidics conditions. It was shown that the technique of micro segmented flow is well suited for the investigation of dependence of bacterial growth on different concentrations of either single metal ions or combinations of them. This study confirms higher tolerance to Zn than to Cu by our test organism. The highly resolved dose-response curves reflect two transitions between the different growth behaviors, separating initial responses to Cu concentration ranges into those with (a) intense growth, (b) moderate growth, and (c) growth inhibition. For Streptomyces sp. F4, an initial stimulation was shown in the sublethal range of zinc sulfate. Two-dimensional screenings using computer-controlled fluid actuation and in situ micro flow-through fluorimetry reflected a strong growth stimulation of strain F4 by zinc sulfate in the presence of sublethal Cu concentrations. This stimulatory effect on binary mixtures may be useful in providing optimal growth conditions in bioremediation procedures.

Droplet‐based microfluidics for microtoxicological studies

“…Life Sci. 2015, 00, 1-12 www.biotecvisions.com salts [64,82,83,88] as well as antibiotics [53,67,68,89,90] and other drugs [84,[91][92][93], and food components [80]. The obtained highly resolved dose/response functions from microfluidic investigations reflect roughly the same EC 50 values as observed in conventional screenings.…”

“…Dose-dependent stimulation has also been found in 2D microtoxicological studies with metal-tolerant strains Streptomyces sp. F4 on zinc in the presence of sublethal cooper concentration [82] (Fig. 2F).…”

“…The spectrum of the analyzed organisms spans from bacteria as E. coli [53,57,67,74,[79][80][81] and Streptomyces [82], to eukaryotic microorganisms as Chlorella vulgaris [83], to multicellular organisms [64,65,84], animal cell lines [85], and human cells cultures such as human embryonic kidney (HEK) [86] and Jurkat cells [86,87]. The test substances involve heavy metal www.els-journal.com Eng.…”

Changing growth behavior of heavy‐metal tolerant bacteria: Media optimization using droplet‐based microfluidics

“…The half minimal inhibitory concentration value against copper-II ions for B. sporothermodurans PLO1 was about 0.4 mM. For S. tendae F4 a copper tolerance of 0.6 mM CuSO 4 had been described earlier [11]. For further experiments CuSO 4 could be used at sublethal concentration (0.25 mM) to investigate effects of (NH 4 ) 2 HPO 4 on heavy-metal stressed bacteria.…”

Precision moulding of biomimetic disposable chips for droplet-based applications

“…An increasing number of research groups use such micro-reactors for biological applications, e.g. for screening of microorganisms regarding their potential to produce pharmaceuticals (Zang et al 2013) and to discover novel enzymes (Beneyton et al 2016) or for investigating their resistance against heavy metals (Cao et al 2013). Other groups reported about the cultivation of single cells in microfluidic droplets to detect their protein expression quantitatively (Huebner et al 2007) or about screening and development studies on multicellular spheroids (McMillan et al 2016) and even on embryos of multicellular organisms like the zebrafish (Funfak et al 2007).…”