Abstract
Biosulfidogenesis can be used to remediate low pH and high metal content waters such as acid mine drainage and recover the present metals. The selection of a cheap electron donor for the process is important for the economic viability. In this work we isolated a novel versatile acidotolerant fermentative bacterium (strain ALET) that is able to use a great variety of substrates including glycerol. Strain ALET is an obligate anaerobe, and cells are motile, rod-shaped, spore-forming, and stain Gram-positive. Growth occurred in a pH range from 3.5 to 7 (optimum 5.5), and temperature range from 25 to 40°C (optimum 37°C). It grows by fermentation of sugars, organic acids and glycerol. It has the ability to use thiosulfate, iron and DMSO as electron acceptors. Its genome is 4.7 Mb with 5122 protein-coding sequences, and a G+C content of 46.9 mol%. Based on 16S rRNA gene sequence analysis, the closest cultured species is Propionispora hippei (91.4% 16S rRNA gene identity) from the Sporomusaceae family (Selenomonadales order, Negativicutes class, Firmicutes phylum). Based on the distinctive physiological and phylogenetic characteristics of strain ALET, a new genus and species Lucifera butyrica gen. nov., sp. nov., is proposed. The type strain is ALET (=JCM 19373T = DSM 27520T). Strain ALET is an incomplete oxidizer and acetate, among other products, accumulates during glycerol conversion. Strain ALET was used to extend the substrate range for sulfur reduction by constructing co-cultures with the acetate oxidizer and sulfur reducer Desulfurella amilsii. The co-culture was tested with glycerol as substrate in batch and chemostat experiments. Acetate formed by fermentation of glycerol by strain ALET resulted in sulfur reduction by D. amilsii. The co-culture strategy offers good perspectives to use a wide range of cost-efficient substrates, including glycerol, to produce sulfide by specialized sulfur reducers. The recovery of heavy metals from metalliferous streams may become economically feasible by this approach.Note: The locus tag for the genes encoded in Lucifera butyrica is LUCI_∗. To avoid repetition of the prefix along the text, the locus tags are represented by the specific identifier.
Highlights
Respiration of sulfur compounds for the production of hydrogen sulfide is applied for the biotechnological recovery of metals (Sánchez-Andrea et al, 2014; Florentino et al, 2016b)
Campbell et al (2015) showed that the phylogenetic reconstruction based on 16S rRNA gene analysis of the former Selemonadales incertae sedis presents limited resolution, observation confirmed in our 16S rRNA gene phylogenetic reconstruction of the Sporomusaceae family (Figure 1A)
This whole genome reconstruction show a stable separation within the different members of Sporomusaceae family and Veillonella parvula as representative of Veillonellaceae family with a bootstrap value of 100%
Summary
Respiration of sulfur compounds for the production of hydrogen sulfide is applied for the biotechnological recovery of metals (Sánchez-Andrea et al, 2014; Florentino et al, 2016b). The utilization of elemental sulfur has gained attention as, compared to sulfate, four times less electron donor is necessary for the production of an equivalent amount of sulfide (Florentino et al, 2015). The ability to reduce elemental sulfur is widespread among bacteria and archaea (Florentino et al, 2015) and sulfur-reducers can use a variety of electron donors, including hydrogen, alcohols, organic acids, sugars, starch and molasses (Bonch-Osmolovskaya et al, 1990; Finster et al, 1997; Dirmeier et al, 1998; Boyd et al, 2007). Substrate range of D. amilsii is rather limited and it is not capable of using, for instance, poly- and monosaccharides, alcohols or glycerol (Florentino et al, 2016a)
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