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Keywords = initial formation of Leptothrix sheath

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9 pages, 2184 KiB  
Article
Dissociation and Re-Aggregation of Multicell-Ensheathed Fragments Responsible for Rapid Production of Massive Clumps of Leptothrix Sheaths
by Tatsuki Kunoh, Noriyuki Nagaoka, Ian R. McFarlane, Katsunori Tamura, Mohamed Y. El-Naggar, Hitoshi Kunoh and Jun Takada
Biology 2016, 5(3), 32; https://doi.org/10.3390/biology5030032 - 1 Aug 2016
Cited by 8 | Viewed by 5745
Abstract
Species of the Fe/Mn-oxidizing bacteria Leptothrix produce tremendous amounts of microtubular, Fe/Mn-encrusted sheaths within a few days in outwells of groundwater that can rapidly clog water systems. To understand this mode of rapid sheath production and define the timescales involved, behaviors of sheath-forming [...] Read more.
Species of the Fe/Mn-oxidizing bacteria Leptothrix produce tremendous amounts of microtubular, Fe/Mn-encrusted sheaths within a few days in outwells of groundwater that can rapidly clog water systems. To understand this mode of rapid sheath production and define the timescales involved, behaviors of sheath-forming Leptothrix sp. strain OUMS1 were examined using time-lapse video at the initial stage of sheath formation. OUMS1 formed clumps of tangled sheaths. Electron microscopy confirmed the presence of a thin layer of bacterial exopolymer fibrils around catenulate cells (corresponding to the immature sheath). In time-lapse videos, numerous sheath filaments that extended from the periphery of sheath clumps repeatedly fragmented at the apex of the same fragment, the fragments then aggregated and again elongated, eventually forming a large sheath clump comprising tangled sheaths within two days. In this study, we found that fast microscopic fragmentation, dissociation, re-aggregation and re-elongation events are the basis of the rapid, massive production of Leptothrix sheaths typically observed at macroscopic scales. Full article
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11 pages, 6086 KiB  
Article
Autolysis of Bacterial Cells Leads to Formation of Empty Sheaths by Leptothrix spp.
by Tomoko Suzuki, Hiromichi Ishihara, Kazuhiro Toyoda, Tomonori Shiraishi, Hitoshi Kunoh and Jun Takada
Minerals 2013, 3(2), 247-257; https://doi.org/10.3390/min3020247 - 20 Jun 2013
Cited by 10 | Viewed by 9089
Abstract
The aquatic, Fe-oxidizing bacteria Leptothrix spp. produce uniquely shaped extracellular sheaths composed of organic bacterial polymers encrusted with inorganic elements from its aquatic environments. At the initial stage of sheath formation, bacterial cells were aligned in the sheath, but later most sheaths became [...] Read more.
The aquatic, Fe-oxidizing bacteria Leptothrix spp. produce uniquely shaped extracellular sheaths composed of organic bacterial polymers encrusted with inorganic elements from its aquatic environments. At the initial stage of sheath formation, bacterial cells were aligned in the sheath, but later most sheaths became empty. Here, we studied the mechanism of sheath hollowing by examining an isolate of Leptothrix sp. strain OUMS1 cultured in either artificial medium or natural groundwater. After 3 days in the medium, most sheaths at the initial stage surrounded a line of live cells, while some cells in the line were dead regardless of their position in a sheath. In sheaths where cells and/or their remnants were barely distinguishable by differential interference contrast microscopy (DIC), a vital stain and a stain specific for nucleic acids occasionally revealed dead cells and/or nucleic acid remnants, while sheaths that lacked a positive response to these reagents looked transparent when viewed with DIC. In specimens cultured in the medium for 7 days, dead cells increased in number regardless of their position in the sheath. Almost the same phenomena occurred in specimens cultured in natural groundwater until day 7. Transmission electron microscopy (TEM) showed that cells degenerated, leading to autolysis of bacterial cells in the sheath. These observations led us to conclude that autolysis of bacterial cells could be a major cause of sheath hollowing. Full article
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9 pages, 687 KiB  
Article
Initial Parallel Arrangement of Extracellular Fibrils Holds a Key for Sheath Frame Construction by Leptothrix sp. Strain OUMS1
by Hiromichi Ishihara, Tomoko Suzuki, Hideki Hashimoto, Hitoshi Kunoh and Jun Takada
Minerals 2013, 3(1), 73-81; https://doi.org/10.3390/min3010073 - 22 Feb 2013
Cited by 10 | Viewed by 6277
Abstract
Early stages of sheath formation by Leptothrix sp. strain OUMS1 and its derivative sheathless mutant grown in media with or without Fe were examined by light and electron microscopy. Results showed that the initial parallel arrangement of fibrils excreted from the cells holds [...] Read more.
Early stages of sheath formation by Leptothrix sp. strain OUMS1 and its derivative sheathless mutant grown in media with or without Fe were examined by light and electron microscopy. Results showed that the initial parallel arrangement of fibrils excreted from the cells holds a key for subsequent construction of the sheath frame and that aqueous-phase Fe interacts with excreted fibrils whether fibrils are parallel-arranged or simply-intermingled. Full article
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11 pages, 419 KiB  
Article
A Novel Method for Culturing of Leptothrix sp. Strain OUMS1 in Natural Conditions
by Tomoko Suzuki, Hiromichi Ishihara, Mitsuaki Furutani, Tomonori Shiraishi, Hitoshi Kunoh and Jun Takada
Minerals 2012, 2(2), 118-128; https://doi.org/10.3390/min2020118 - 23 May 2012
Cited by 13 | Viewed by 7878
Abstract
Although some strains of Leptothrix spp. isolated from aquatic environments have been characterized by culturing them in laboratory conditions, they often show morphological and chemical features distinct from those found in natural environments. To resolve this discrepancy, a novel cultivation method was devised [...] Read more.
Although some strains of Leptothrix spp. isolated from aquatic environments have been characterized by culturing them in laboratory conditions, they often show morphological and chemical features distinct from those found in natural environments. To resolve this discrepancy, a novel cultivation method was devised for culturing such strains in natural groundwater. Leptothrix sp. strain OUMS1 was pre-cultured in a medium lacking Fe for 2 days, and then injected into a small dialysis tube bag and immersed in a container with continuously flowing groundwater for 1–3 and 14 days. Microscopic analysis of the initial phase of sheath formation and arbitrary comparisons with medium cultures revealed that in groundwater the surface coat of the sheath comprised much thinner fibrils, and an inner sheath wall that was much thinner and more indistinct compared with medium cultures. These differences were probably attributable to poorer secretion from the cell surface in groundwater conditions. A nutrient-rich medium likely activates cell metabolism and promotes secretion, resulting in a thicker inner sheath wall and thicker outer coat fibrils. Aqueous-phase Fe was deposited on immature sheaths in a similar manner in both cultures. These results indicate that laboratory culture of isolated microbes does not always reflect their characteristics in natural environments. Full article
(This article belongs to the Special Issue Advances in Biominerals)
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10 pages, 2536 KiB  
Article
Initial Assemblage of Bacterial Saccharic Fibrils and Element Deposition to Form an Immature Sheath in Cultured Leptothrix sp. Strain OUMS1
by Mitsuaki Furutani, Tomoko Suzuki, Hiromichi Ishihara, Hideki Hashimoto, Hitoshi Kunoh and Jun Takada
Minerals 2011, 1(1), 157-166; https://doi.org/10.3390/min1010157 - 14 Dec 2011
Cited by 28 | Viewed by 8062
Abstract
In an aquatic environment, the genus Leptothrix produces an extracellular Fe- or Mn-encrusted tubular sheath composed of a complex hybrid of bacterial exopolymers and aqueous-phase inorganic elements. This ultrastructural study investigated initial assemblage of bacterial saccharic fibrils and subsequent deposition of aqueous-phase inorganic [...] Read more.
In an aquatic environment, the genus Leptothrix produces an extracellular Fe- or Mn-encrusted tubular sheath composed of a complex hybrid of bacterial exopolymers and aqueous-phase inorganic elements. This ultrastructural study investigated initial assemblage of bacterial saccharic fibrils and subsequent deposition of aqueous-phase inorganic elements to form the immature sheath skeleton of cultured Leptothrix sp. strain OUMS1. After one day of culture, a globular and/or thread-like secretion was observed on the surface of the bacterial cell envelope, and secreted bodies were transported across the intervening space away from the cell to form an immature sheath skeleton comprising assembled and intermingled fibrils. Energy dispersive X-ray microanalysis and specific Bi-staining detected a distinguishable level of P, trace Si, and a notable amount of carbohydrates in the skeleton, but not Fe. By the second day, the skeleton was prominently thickened with an inner layer of almost parallel aligned fibrils, along with low level of Fe deposition, whereas an outer intermingled fibrous layer exhibited heavy deposition of Fe along with significant deposition of P and Si. These results indicate that basic sheath-construction proceeds in two steps under culture conditions: an initial assemblage of bacterial saccharic fibrils originated from the cell envelope and the subsequent deposition of aqueous-phase Fe, P, and Si. Full article
(This article belongs to the Special Issue Advances in Biominerals)
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