ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

sulfur oxidising bacteria and sulfur reducing bacteria

Updated on February 12, 2015


Sulfur utilizing bacteria includes Sulfur oxidizing bacteria and Sulfur reducing bacteria. Sulfur oxidizing bacteria are chemolithotrophic bacteria that derive energy from the oxidation of inorganic molecules. Sulfur reducing bacteria are bacteria that use elemental sulfur, hydrogen sulfide or its partially reduced oxides such as energy sources. All these are converted to sulfate.

Sulfur oxidizing bacteria are bacteria that oxidise hydrogen sulfide with the formation of intracellular sulfur deposits. Examples are Filamentous gliding bacteria like Beggiatoa, Thiothrix; Very large unicellular gliding bacteria like Achromatium; Large unicellular rod shaped or spiral bacteria like Thiobacterium, Thiospira, Macromonas, Thiovulum; and Bacteria that oxidise hydrogen sulfide with the formation of extracellular sulfur deposits; cell size is small: Thiobacillus, Thiomicrospira.

Energy generation by sulfur oxidation includes the oxidation of elemental sulfur to sulfate:

Sulfide--------polysulfide------------- elemental sulfur ---------------sulfite ------------ sulfate

Energy generation by sulfur oxidation also includes Formation of adenosine 5’ phosphosulfate (APS)

SO32- + 2AMP -------------------- 2APS + 4 e-

2APS + 2Pi -------------------------- 2ADP + 2SO42-

2ADP ---------------------------------- AMP + ATP

2SO32- + AMP +2Pi ----------- 2SO4 2- + ATP + 4e-

Here, sulfur oxidation proceeds with the activation of AMP to form APS followed by phosphorolysis with phosphate or pyrophosphate to yield ADP or ATP respectively.

Sulfur oxidizing bacteria are extreme acid tolerates, growing at pH 1 to 2.these are often found in special environments in which pH is maintained at low level by their metabolic activities. Some like Thiobacillus occur widel in both marine and terrestrial environment. Strong acidophilic species is Thiobacillus thiooxidans. Some species of Sulfur oxidizing bacteria gain energy from the oxidation of hydrogen sulfide and can couple this energy generation to the assimilation of organic carbon source, a form of metabolism termed as mixotrophy. An advantage of sulfur oxidation by Sulfur oxidizing bacteria is that it aids in establishment of symbiosis with rice plants. Example is Beggiatoa. Also sulfur accumulation provides an electron acceptor under anaerobic conditions.




Sulfur reducing bacteria are gram negative Eubacteria and are strict anaerobes that are capable of anaerobic respiration utilizing a variety of oxidized compounds of sulfur as an electron acceptor.

As of 2009, 60 genera containing 220 species of sulfate-reducing bacteria were known. Among the Deltaproteobacteria the orders of sulfate-reducing bacteria include Desulfobacterales, Desulfovibrionales and Syntrophobacterales. This accounts for the largest group of sulfate-reducing bacteria, about 23 genera. The second largest group of sulfate-reducing bacteria is found among the Firmicutes, including the genera Desulfotomaculum, Desulfosporomusa, and Desulfosporosinus. In the Nitrospirae division we find sulfate-reducing Thermodesulfovibrio species. Two more groups that include thermophile sulfate-reducing bacteria are given their own phyla, the Thermodesulfobacteria and Thermodesulfobium. There are also three genera of Archaea known to be capable of sulfate reduction: Archaeoglobus, Thermocladium and Caldivirga. They are found in hydrothermal vents, oil deposits, and hot springs. Desulfovibio are curved; rod shaped or spiral in shape. Desulfomonas are rod shaped. Desulfobacter are coccus in shape. Desulfococcus are coccus or ellipsoidal in shape. Desulfosarcina are arranged as packets of cocci. Desulfuromonas are rods in shape and does not utilize sulfate as electron acceptor unlike others.

These are present in sulfate containing sediments especially marine and estuarine ones. Some also occurs in rumen and in the intestinal tract of non ruminant animals. For all the sulfur reducing bacteria, electron donors are the fermentative end products that are produced by other anaerobic bacteria. Hence lactate, ethanol, short chain fatty acids, formate and hydrogen are used by them. Acetate cannot be oxidized by many due to their incomplete tri carboxylic acid cycle. Others have a complete TCA cycle and can oxidize acetate to carbon dioxide. Hydrogen plays a central role in the metabolism of those sulfur reducing bacteria that cannot oxidize acetate. Sulfate reduces intracellularly resulting in the hydrogen cycling which is equivalent to the respiratory pumping of protons and results in the proton motive force.

When sulfate diffuses into reduced habitats, it provides an opportunity for different groups of microorganisms to carry out sulfate reduction. This use of sulfate as an external electron acceptor to form sulfide, which accumulates in the environment, is an example of a dissimilatory reduction process and anaerobic respiration. In comparison, the reduction of sulfate into organic sulfur from for use in amino acids and protein biosynthesis is described as an assimilatory reduction process. Example is Desulfuromonas. Sulfate is activated by esterification to an adenyl group by the enzyme ATP sulfurylase to form adenosyl phophosulfate and pyrophosphate. The equilibrium m of this reaction les strongly towards ATP and sulfate so the isolated reaction does not proceed.

However, in vivo one of the products, pyrophosphate is rapidly hydrolyzed by the action of pyrophosphatase thereby allowing the other product, adenosyl phophosulfate to accumulate in significant quantities. Adenosyl phosphosulfate is then reductively cleaved to yield AMP and bisulfite. The reduction of bisulfite may occur in three successive two electron transfers to enzyme bound intermediates such that then trithionite and thiosulfate are byproducts rather than intermediats of the pathway. The enzyme bisulfite reductase is present in all sulfur reducing bacteria. It catalyzed the reduction of bisulfite to trithionite, also producing variable amounts of thiosulfate and sulfide.

Two taxonomc different classes of bisulfite reductases occur in sulfur reducers. These are Desulfoviridin (green protein), and Desulforubidin (reddish brown protein). Both enzymes contains nonheme iron and an unusual class of prosthetic group termed siroheme, an iron chelating tetra pyrole in which two of the pyrole rings are reduced.

Sulfate-reducing bacteria
Sulfate-reducing bacteria
Sulfur Cycle Bacteria
Sulfur Cycle Bacteria


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)