[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-398681-105":59,"doc-detail-398681-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","biochemical-reaction-tests","Biochemical Reaction Tests","","Biochemical Reaction Tests describe how bacteria perform biochemical activities using enzymes that govern transformations both inside and outside the cell. The manual section explains bacterial identification through fermentation and metabolic by-products, including sugars fermentation with pH indicators and gas detection using Durham tubes. It also covers indole production using Kovacs’ reagent, methyl red and Voges-Proskauer tests for distinguishing enteric bacteria, citrate utilization with alkaline color change, and catalase and oxidase-based differentiation by enzyme presence and oxygen-related reactions.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/biochemical-reaction-tests/398681/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/biochemical-reaction-tests/398681.png","ImageObject",300,407,{"name":92,"@type":93},"Melati","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-30","2026-09-27",true,{"@type":102,"interactionType":103,"userInteractionCount":44},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"How does the Sugars Fermentation test help identify microorganisms?","Question",{"text":112,"@type":113},"Microorganisms ferment carbohydrates into characteristic end products such as acids, gases, or other molecules. pH indicators and Durham tube gas detection make these differences observable for identification.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"What does a positive Indole Production test indicate?",{"text":117,"@type":113},"Indole accumulates in the medium when bacteria produce indole from tryptophan. Adding Kovacs’ reagent forms a bright red surface compound, indicating a positive result.",{"name":119,"@type":110,"acceptedAnswer":120},"How do Methyl Red and Voges-Proskauer tests differ in their targets?",{"text":121,"@type":113},"Methyl red detects pH changes into the acid range from acidic end products, distinguishing mixed acid from butanediol fermenters. Voges-Proskauer detects the synthesis of 2,3-butanediol (acetoin) using KOH and Barritt’s reagent, shown by a cherry-red color after reagent addition.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},398681,1790791870,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":44,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":24,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144,"preview_page_count":4},962085570644,"https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d","Biochemical Reaction Tests  \nBacteria accomplish their various biochemical activities (growth and multiplication) using raw materials (nutrients) obtained from the environment. The biochemical transformations that occur both inside and outside of bacteria are governed by biological catalysts called enzymes.  \nThis part of the laboratory manual presents the ability of bacteria to use enzymes and degrade carbohydrates, lipids, proteins, and amino acids. The metabolism, or use, of these organic molecules often produces by-products that can be used in the identification and characterization of bacteria.  \nSugars Fermentation test  \nFermentations are energy-producing biochemical reactions in which organic molecules serve both as electron acceptors and donors. The ability of microorganisms to ferment carbohydrates and the types of products formed are very useful in identification. A given carbohydrate may be fermented to a number of different end products depending upon the microorganism involved. These end products (alcohols, acids, gases, or other organic molecules) are characteristic of the particular microorganisms. For example, if fermenting bacteria are grown ina liquid culture medium containing the carbohydrate glucose, they may produce organic acids as by-products of the fermentation. These acids are released into the medium and lower its pH. If a pH indicator such as phenol red or bromcresol purple is included in the medium, the acid production will change the medium from its original color to yellow (figures 1).  \nGases produced during the fermentation process can be detected by using a small, inverted tube, called a Durham tube within the liquid culture medium. After adding the proper amount of broth, Durham tubes are inserted into each culture tube. During autoclaving, the air is expelled from the Durham tubes, and they become filled with the medium. If gas is produced, the liquid medium inside the Durham tube will be displaced, entrapping the gas in the form of a bubble.  \nFigures 1: Sugars Fermentation test  \nIndole Production test  \nThe amino acid tryptophan is found in nearly all proteins. Bacteria that contain the enzyme tryptophanase can hydrolyze tryptophan to its metabolic products, mainly, indole, pyruvic acid, and ammonia. The bacteria use the pyruvic acid and ammonia to satisfy nutritional needs; indole is not used and accumulatesin the medium. The presence of indole can be detected by the addition of Kovacs’reagent. Kovacs’ reagent reacts with the indole, producing a bright red compound on the surface of the medium (figures.2).  \nFigures.2: Indole Production test  \nMethyl Red Test  \nAll enteric bacteria catabolize glucose for their energy needs; however, the end products vary depending on the enzyme pathways present in the bacteria. The pH indicator methyl red detects a pH change to the acid range as a result of acidic end products such as lactic, acetic, and formic acids. This test is of value in distinguishing between E. coli (a mixed acid fermenter) and E. aerogenes (abutanediol fermenter).  \nMixed acid fermenters such as E. coli produce a mixture of fermentation acids and thus acidify the medium. Butanediol fermenters such as E. aerogenes form butanediol (acetoin), and fewer organic acids. The pH of the medium does not fall as low as during mixed acid fermentation. As illustrated in figure.3, at a  \npH of 4, the methyl red indicator turns Red (a positive methyl red test). At a pH of 6, the indicator turns yellow (a negative methyl red test).  \nVoges-Proskauer Test  \nThe Voges Proskauer test identifies bacteria that ferment glucose, leading  \nto medium. The addition of 40% KOH and a  \n5% absolute ethanol (Barritt’s reagent) will detect the the synthesis of 2,3-butanediol.  \nIn the presence of the reagents and acetoin, a cherry-red color develops. Development of a red color in the culture medium with 15 minutes following the addition of Barritt’s reagent represents a positive VP test; absence of a red color","cbCaivpnHqIJ8Aio","https://ap.wps.com/l/cbCaivpnHqIJ8Aio","pdf",297058,"English","# Biochemical Reaction Tests\n## Sugars Fermentation test\n## Indole Production test\n## Methyl Red Test\n## Voges-Proskauer Test\n## Citrate Utilization Test\n## Catalase test\n## Oxidase test","[{\"question\":\"How does the Sugars Fermentation test help identify microorganisms?\",\"answer\":\"Microorganisms ferment carbohydrates into characteristic end products such as acids, gases, or other molecules. pH indicators and Durham tube gas detection make these differences observable for identification.\"},{\"question\":\"What does a positive Indole Production test indicate?\",\"answer\":\"Indole accumulates in the medium when bacteria produce indole from tryptophan. Adding Kovacs’ reagent forms a bright red surface compound, indicating a positive result.\"},{\"question\":\"How do Methyl Red and Voges-Proskauer tests differ in their targets?\",\"answer\":\"Methyl red detects pH changes into the acid range from acidic end products, distinguishing mixed acid from butanediol fermenters. Voges-Proskauer detects the synthesis of 2,3-butanediol (acetoin) using KOH and Barritt’s reagent, shown by a cherry-red color after reagent addition.\"}]","Biochemical Reaction Tests | PDF",1790488043,13]