As Lovley explains, \u201cMicrobial nanowires are a revolutionary electronic material with substantial advantages over man-made materials. Chemically synthesizing nanowires in the lab requires toxic chemicals, high temperatures and\/or expensive metals. The energy requirements are enormous. By contrast, natural microbial nanowires can be mass-produced at room temperature from inexpensive renewable feedstocks in bioreactors with much lower energy inputs. And the final product is free of toxic components.\u201d<\/p>\n
![\"\"](\"http:\/\/www.kurzweilai.net\/images\/G.-sulfurreducens-biofilm.png\" "\\"G.")
Confocal scanning laser micrographs of G.\u00a0sulfurreducens anode biofilms harvested on day 10. Bar, 25\u00a0\u00b5m. (credit: Yang Tan et al.\/mBio)<\/p><\/div>\n
The Microbial nanowires offer an unprecedented potential for developing novel electronic devices and sensors for diverse applications with a new environmentally friendly technology, Lovely says. \u201cThis is an important advance in microbial nanowire technology. The approach we outline in this paper demonstrates a rapid method for prospecting in nature to find better electronic materials.\u201d<\/p>\n
When his lab began looking at the protein filaments of other\u00a0Geobacter\u00a0<\/em>species, they were surprised to find a wide range in conductivities. For example, one species recovered from uranium-contaminated soil produced poorly conductive filaments. However, another species,\u00a0Geobacter metallireducens<\/em> produced nanowires 5,000 times more conductive than the\u00a0G. sulfurreducens\u00a0<\/em>wires. Lovley recalls, \u201cI isolated\u00a0metallireducens\u00a0<\/em>from mud in the Potomac River 30 years ago, and every couple of years it gives us a new surprise.\u201d<\/p>\nIn their new study supported by the U.S. Office of Naval Research, they did not study the\u00a0G. metallireducens\u00a0<\/em>strain directly. Instead, they took the gene for the protein that assembles into microbial nanowires from it and inserted this into\u00a0G. sulfurreducens<\/em>. The result is a genetically modified\u00a0G. sulfurreducens<\/em>\u00a0that expresses the\u00a0G. metallireducens\u00a0<\/em>protein, making nanowires much more conductive than\u00a0G. sulfurreducens\u00a0<\/em>would naturally produce.<\/p>\nFurther, Lovley says, \u201cWe have found that\u00a0G. sulfurreducens\u00a0<\/em>will express filament genes from many different types of bacteria. This makes it simple to produce a diversity of filaments in the same microorganism and to study their properties under similar conditions.\u201d<\/p>\nThe high conductivity of the\u00a0G. metallireducens\u00a0<\/em>nanowires suggests that they may be an attractive material for the construction of conductive materials, electronic devices ,and sensors for medical or environmental applications. The authors say discovering more about the mechanisms of nanowire conductivity \u201cprovides important insight into how we might make even better wires with genes that we design ourselves.\u201d<\/p>\n
\nAbstract of\u00a0Expressing the Geobacter metallireducens PilA in Geobacter sulfurreducens Yields Pili with Exceptional Conductivity<\/em><\/h4>\nThe electrically conductive pili (e-pili) of\u00a0Geobacter sulfurreducens<\/em>\u00a0serve as a model for a novel strategy for long-range extracellular electron transfer. e-pili are also a new class of bioelectronic materials. However, the only other\u00a0Geobacter<\/em>\u00a0pili previously studied, which were from\u00a0G.\u00a0uraniireducens<\/em>, were poorly conductive. In order to obtain more information on the range of pili conductivities in\u00a0Geobacter<\/em>\u00a0species, the pili of\u00a0G.\u00a0metallireducens<\/em>\u00a0were investigated. Heterologously expressing the PilA gene of\u00a0G.\u00a0metallireducens<\/em>\u00a0in\u00a0G.\u00a0sulfurreducens<\/em>\u00a0yielded a\u00a0G.\u00a0sulfurreducens<\/em>\u00a0strain, designated strain MP, that produced abundant pili. Strain MP exhibited phenotypes consistent with the presence of e-pili, such as high rates of Fe(III) oxide reduction and high current densities on graphite anodes. Individual pili prepared at physiologically relevant pH\u00a07 had conductivities of 277 \u00b1 18.9 S\/cm (mean \u00b1 standard deviation), which is 5,000-fold higher than the conductivity of\u00a0G.\u00a0sulfurreducens<\/em>\u00a0pili at pH\u00a07 and nearly 1 million-fold higher than the conductivity of\u00a0G.\u00a0uraniireducens<\/em>\u00a0pili at the same pH. A potential explanation for the higher conductivity of the\u00a0G.\u00a0metallireducens<\/em>\u00a0pili is their greater density of aromatic amino acids, which are known to be important components in electron transport along the length of the pilus. The\u00a0G.\u00a0metallireducens<\/em>\u00a0pili represent the most highly conductive pili found to date and suggest strategies for designing synthetic pili with even higher conductivities.<\/p>\n","protected":false},"excerpt":{"rendered":" UMass Amherst research finds microbe yields better electronic material Microbiologists at the University of Massachusetts Amherst report that they have discovered a new type of microbial nanowire produced by bacteria that could greatly accelerate the development of sustainable “green” conducting materials for the electronics industry. The study by Derek Lovley and colleagues appears this week […]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,48,43],"tags":[],"class_list":["post-13332","post","type-post","status-publish","format-standard","hentry","category-biotech","category-electronics","category-news"],"_links":{"self":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/13332"}],"collection":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/comments?post=13332"}],"version-history":[{"count":1,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/13332\/revisions"}],"predecessor-version":[{"id":13333,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/13332\/revisions\/13333"}],"wp:attachment":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/media?parent=13332"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/categories?post=13332"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/tags?post=13332"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"\"](\"http:\/\/www.kurzweilai.net\/images\/Geobacter-Nanowires.jpg\" "\\"Geobacter")