Isolation of a Leptothrix Strain, OUMS1, from Ocherous Deposits in Groundwater

Abstract

Leptothrix species in aquatic environments produce uniquely shaped hollow microtubules composed of aquatic inorganic and bacterium-derived organic hybrids. Our group termed this biologically derived iron oxide as "biogenous iron oxide (BIOX)". The artificial synthesis of most industrial iron oxides requires massive energy and is costly while BIOX from natural environments is energy and cost effective. The BIOX microtubules could potentially be used as novel industrial functional resources for catalysts, adsorbents and pigments, among others if effective and efficient applications are developed. For these purposes, a reproducible system to regulate bacteria and their BIOX productivity must be established to supply a sufficient amount of BIOX upon industrial demand. However, the bacterial species and the mechanism of BIOX microtubule formation are currently poorly understood. In this study, a novel Leptothrix sp. strain designated OUMS1 was successfully isolated from ocherous deposits in groundwater by testing various culture media and conditions. Morphological and physiological characters and elemental composition were compared with those of the known strain L. cholodnii SP-6 and the differences between these two strains were shown. The successful isolation of OUMS1 led us to establish a basic system to accumulate biological knowledge of Leptothrix and to promote the understanding of the mechanism of microtubule formation. Additional geochemical studies of the OUMS1-related microstructures are expected provide an attractive approach to study the broad industrial application of bacteria-derived iron oxides.

Preparation and properties of ferrite derived from iron oxidizing bacteria

“…In this paper, according to the enrichment and deposition mechanism of iron and manganese [7][8][9][10][11][12], the sediment composition, the microstructure characteristics [15] and other basic research of iron bacteria, the Sphaerotilus natans which were separated from activity mud of Xiamen sewage treatment plant and the Leptothrix discophora which was purchased from ATCC, were used to deposit the iron and manganese ions respectively. The Sediments were collected and heat treated at high temperature to obtain the ferrite.…”

“…It was shown that iron bacteria are widespread in various types of nature waters, which have the capacity of oxidizing and depositing ferrous ions and manganese ions in water efficiently. This microbe could be directly used to obtain composites with a variety of shapes such as fiber, tube and film [7][8][9][10][11][12][13][14][15][16] and has the potential to fabricate the ferrite materials. Compared to traditional chemical synthesis [5], there may be a breakthrough in the aspects of physical control, particle reunion and industrialization.…”

“…This microbe could be directly used to obtain composites with a variety of shapes such as fiber, tube and film [7][8][9][10][11][12][13][14][15][16] and has the potential to fabricate the ferrite materials. Compared to traditional chemical synthesis [5], there may be a breakthrough in the aspects of physical control, particle reunion and industrialization.In this paper, according to the enrichment and deposition mechanism of iron and manganese [7][8][9][10][11][12], the sediment composition, the microstructure characteristics [15] and other basic research of iron bacteria, the Sphaerotilus natans which were separated from activity mud of Xiamen sewage treatment plant and the Leptothrix discophora which was purchased from ATCC, were used to deposit the iron and manganese ions respectively. The Sediments were collected and heat treated at high temperature to obtain the ferrite.…”

Autolysis of Bacterial Cells Leads to Formation of Empty Sheaths by Leptothrix spp.

“…When OUMS1 was cultured in silicon-glucose-peptone broth (SGP broth [13]) with a small iron plate (hereafter referred to as SGPI broth) for 3 days, a great number of the initial sheaths surrounding chained cells were seen in addition to abundant free or aggregated cells, as reported previously [6]. The adjacent, aligned cells ( Figure 2A, solid arrow) in the initial sheath comprised a faint, thin film but were not always tightly connected, and thus intercellular spaces were often observed with DIC microscopy ( Figure 2A, dotted arrow).…”

“…The genus Leptothrix, a type of Fe/Mn-oxidizing bacteria belonging to the aquatic β-proteobacteria [1][2][3], is characterized by its formation of an extracellular, tubular, Fe-or Mn-encrusted sheath, enabled by the Fe/Mn-oxidizing capacities of this genus [4][5][6]. The formation of a sheath that contains bacterial cells and extracellular metal-oxidizing activities are the two major phenotypic criteria that distinguish Leptothrix species from closely related bacteria [1,7].…”