Practical Microbiology For Secondary Schools

UsingUsing thisthis resourceresourceGoodGood microbiologicalmicrobiological laboratorylaboratorypracticepracticePhotocopiable double-page spreads are providedPhotocopiable double-page spreads are providedfor each investigation. The right-hand page offor each investigation. The right-hand page ofeach spread is the student worksheet, illustratedeach spread is the student worksheet, illustratedwith simple line drawings, whilst the left-handwith simple line drawings, whilst the left-handpage provides notes for teachers and technicianspage provides notes for teachers and techniciansto assist with preparation and risk assessment,to assist with preparation and risk assessment,including a list of materials required andincluding a list of materials required andsuggestions for student questions. Both pagessuggestions for student questions. Both pagesprovide planning support. It should be noted thatprovide planning support. It should be noted thatmany investigations require up to a week formany investigations require up to a week formicrobial growth to occur before usable results aremicrobial growth to occur before usable results areavailable.available.The worksheets are arranged in four main themesThe worksheets are arranged in four main themeswhich relate to areas of the National Curriculumwhich relate to areas of the National Curriculumfor Science for England and Wales and the Scottishfor Science for England and Wales and the Scottishspecifications, supporting, in particular, the Keyspecifications, supporting, in particular, the KeyStage 3 Schemes of Work. Investigations can beStage 3 Schemes of Work. Investigations can beselected to fit individual teaching programmes;selected to fit individual teaching programmes;they are not intended to be used in sequence.they are not intended to be used in sequence.Each activity is stand-alone and offers studentsEach activity is stand-alone and offers studentsthe opportunity to develop the investigative skillsthe opportunity to develop the investigative skillsrequired for National Curriculum Key Stages 3required for National Curriculum Key Stages 3and 4. To help students experience the wholeand 4. To help students experience the wholeprocess of investigating selected problems fromprocess of investigating selected problems fromstart to finish, two suggestions for open-endedstart to finish, two suggestions for open-endedexplorations using micro-organisms are providedexplorations using micro-organisms are providedon pp. 42 and 43.on pp. 42 and 43.Whenever working with micro-organisms there areWhenever working with micro-organisms there arepractical procedures to ensure safe transfer andpractical procedures to ensure safe transfer andavoid contamination which are common to mostavoid contamination which are common to mostactivities. An outline of these appears on p. 3,activities. An outline of these appears on p. 3,together with some other useful tips relevant totogether with some other useful tips relevant tomany of the investigations.many of the investigations.Basic Practical Microbiology: A Manual, publishedBasic Practical Microbiology: A Manual, publishedby the SGM, is recommended. Cross references toSociety, is recommended.Crossby thethe MicrobiologySGM, is recommended.Cross referencestospecific techniques in this work are listed on thereferencesto specificin thisworkspecifictechniquesin techniquesthis work arelistedon arethestudent worksheets where appropriate.listed onworksheetsthe studentwhereworksheetswhere appropriate.studentappropriate.Just like any other practical activity in school science, all microbiology investiJust like any other practical activity in school science, all microbiology investigations require the user to adopt good microbiological laboratory practicegations require the user to adopt good microbiological laboratory practice(GMLP). The techniques and activities included in this book, and the micro(GMLP). The techniques and activities included in this book, and the microorganisms suggested, present minimum risk given good practice. Here is a brieforganisms suggested, present minimum risk given good practice. Here is a briefoverview to help those involved in preparing for, or using, the various activioverview to help those involved in preparing for, or using, the various activities to carry them out safely. Further detailed information is available in theties to carry them out safely. Further detailed information is available in theresources listed on p. 44.resources listed on p. 44.Risk assessmentRisk assessmentSchool microbiology will generally be safe, but before any practical activitySchool microbiology will generally be safe, but before any practical activityis undertaken, risks must be assessed. Each individual (be they students,is undertaken, risks must be assessed. Each individual (be they students,technicians or teachers) embarking on a practical activity is responsible for histechnicians or teachers) embarking on a practical activity is responsible for hisor her own health and safety and also for that of others affected by the work.or her own health and safety and also for that of others affected by the work.Risk assessment will involve comparing the steps involved in an intendedRisk assessment will involve comparing the steps involved in an intendedactivity with procedures suggested in model risk assessments.* This willactivity with procedures suggested in model risk assessments.* This willidentify the safety precautions that need to be taken in the context of the levelidentify the safety precautions that need to be taken in the context of the levelof work and, possibly, the need to amend the procedure so that risks to healthof work and, possibly, the need to amend the procedure so that risks to healthand safety from any hazard(s) are minimised. Local rules must also beand safety from any hazard(s) are minimised. Local rules must also becomplied with. Of greatest importance in risk assessment is a consideration ofcomplied with. Of greatest importance in risk assessment is a consideration ofthe skills and behaviour of the students about to tackle a practical activity; athe skills and behaviour of the students about to tackle a practical activity; aprocedure that is safe for one group of individuals may need to be modifiedprocedure that is safe for one group of individuals may need to be modifiedwith a different class. Also important is ensuring that a procedure is safe forwith a different class. Also important is ensuring that a procedure is safe forpupils, but also does not endanger the health and safety of technicians orpupils, but also does not endanger the health and safety of technicians orteachers during preparation or disposal. In deciding on the appropriateteachers during preparation or disposal. In deciding on the appropriateprecautions to adopt, it is prudent that all cultures are treated as potentiallyprecautions to adopt, it is prudent that all cultures are treated as potentiallypathogenic (for example, because of possible contamination). Emergencypathogenic (for example, because of possible contamination). Emergencyprocedures, such as dealing with spills, should also be considered.procedures, such as dealing with spills, should also be considered.No one should perform a microbiological procedure without receivingNo one should perform a microbiological procedure without receivingappropriate training from, or supervision by, a competent person. Informationappropriate training from, or supervision by, a competent person. Informationon suppliers of training is available on p. 44.on suppliers of training is available on p. 44.Microbiology safetyMicrobiology safetyThere are five areas for consideration when embarking on practicalThere are five areas for consideration when embarking on practicalmicrobiology investigations, which make planning ahead essential.microbiology investigations, which make planning ahead essential.Preparation and sterilisation of equipment and culture media.Preparation and sterilisation of equipment and culture media.Storage and maintenance of stocks of microbial cultures for future invest Storage and maintenance of stocks of microbial cultures for future investigations and preparation of an inoculum for the current investigation.igations and preparation of an inoculum for the current investigation.Inoculation of the media with the prepared culture.Inoculation of the media with the prepared culture.Incubation of cultures and sampling during growth, if required.Incubation of cultures and sampling during growth, if required.Sterilisation and safe disposal of all cultures and decontamination ofSterilisation and safe disposal of all cultures and decontamination ofequipment.equipment.Good organisational skills and a disciplined approach ensure that everyGood organisational skills and a disciplined approach ensure that everyactivity is performed both safely and successfully.activity is performed both safely and successfully.Personal protectionPersonal protectionThe publications normally used in schools are:x Topics in Safety, 3rd edition (ASE, 2001)x Safeguards in the School Laboratory, 11th edition(ASE, 2006)*Model risk assessments that can be consulted includeModelrisk anassessmentsthatcan beconsultedinclude*xMicrobiology:HMI GuidePublications,for SchoolsandCD-ROMFurther EducationCLEAPSSScience(latestMicrobiology:an HMISchoolsand FurtherEducation(HMSO1990, nowout ofGuideprint),forTopicsin Safety(ASE 1988,2001),edition)(HMSO1990,now out ofprint), Topicsin Safety2001),CLEAPSSLaboratoryHandbookchapter15.2, pter15.2,HMSO15.12 1996)(CLEAPSSx E;and2001),Safety in Science(DfEE; AHMSOandBiology/BiotechnologySafetyEducationin Microbiology:Code 1996)of omBiology/BiotechnologySafetyin Microbiology:A Code of Practicefor Scottish Schools andColleges(SSERC Ltd, 2002).for ScottishSchoolsand Colleges (SSERC Ltd, 2002).the ASEwebsite)22SGM 20082008SGMMicrobiologySociety 2016Food or drink should not be stored or consumed in a laboratory or prep roomFood or drink should not be stored or consumed in a laboratory or prep roomthat is used for microbiology. No one should lick labels, apply cosmetics, chewthat is used for microbiology. No one should lick labels, apply cosmetics, chewgum, suck pens or pencils or smoke in a laboratory or prep room. Facilitiesgum, suck pens or pencils or smoke in a laboratory or prep room. Facilitiesshould be provided within the laboratory or prep room for hands to be washedshould be provided within the laboratory or prep room for hands to be washedwith soap and warm water after handling microbial cultures and wheneverwith soap and warm water after handling microbial cultures and wheneverleaving the laboratory. Paper towels, or some other hygienic method, shouldleaving the laboratory. Paper towels, or some other hygienic method, shouldbe used for drying hands. If contamination of the hands is suspected, thenbe used for drying hands. If contamination of the hands is suspected, thenthey should be washed immediately with soap. Cuts or abrasions should bethey should be washed immediately with soap. Cuts or abrasions should beprotected by the use of waterproof dressings or disposable gloves. Safetyprotected by the use of waterproof dressings or disposable gloves. Safetyglasses may be worn according to local requirements. Appropriate protectiveglasses may be worn according to local requirements. Appropriate protectiveclothing may be required.clothing may be required.Practical Microbiology for Secondary SchoolsPractical Microbiology for Secondary Schools

Practical techniques and tipsAseptic techniqueSterile equipment and media should be used in the transfer and culture of micro-organisms. Aseptic technique should be observedwhenever micro-organisms are transferred from one container to another. This involves working in an area in which draughts arecontrolled, for example close to a lit Bunsen burner so that there is an updraught of air away from the bench, thereby minimisingthe risk of contaminating open cultures.Flaming loops and bottlesOnly sterile instruments should be used to transfer cultures of micro-organisms. With pipettes or syringes, these will have beenpre-sterilised but, for most transfers, an inoculation loop will be used which is sterilised by heating along its length until it glowsred. This is done both before and after each transfer. When the loop is loaded, beware of ‘splutter’ when the culture is rapidlyheated. This is minimised if the loop is heated first near the handle and slowly drawn through the flame so that the tip of the loopis prewarmed before it reaches the flame. Formation of microbial aerosols is avoided by the careful use of loops and pipettes.The necks of open bottles or tubes should also be flamed, both before and after transfers, by passing them briefly through a hotBunsen burner flame. The aim is not to sterilise the glass (which may break if heating is prolonged), but to create a convectioncurrent of air away from the open mouth of the vessel, so helping to minimise the risk of contaminants entering.Pipettes and syringesA variety of pipettes is available for the aseptic transfer of cultures, suspensions of natural materials and sterile solutions. Usually itis adequate to control the volume to be transferred in terms of the number of drops delivered, e.g. for routine inoculation using aPasteur (dropping) pipette to provide a culture. For measured volumes, e.g. when making dilutions, some form of calibrated pipetteis required. Suitable types include a dropping pipette with volumes marked on the barrel and one that delivers drops of a knownvolume. The long calibrated pipettes that are used in chemistry are also suitable. Pipetting by mouth is forbidden. A teat shouldalways be used. Relatively inexpensive calibrated pipette fillers (e.g. Bibbettes) are also available from suppliers. Syringes and micropipettes holding the appropriate volume provide a useful alternative.A non-absorbent cotton wool plug about 1 cm long is placed in the wide end of the pipette before sterilisation. This preventsairborne microbes from contaminating the fluid being transferred and prevents the operator and environment from contaminationby a culture. However, the cotton wool plug must remain dry because a wet plug does not act as a barrier to the passage of microbes.Glass pipettes should be sterilised in either an autoclave or hot air oven.Handling and labelling agar platesAfter inoculating an agar plate, it is customary to tape the lid to the base to prevent accidental opening. It is best to use clearadhesive tape since masking or biohazard warning tape may obscure the observation of cultures that grow. Only two or four smallpieces of tape are required; covering the top and bottom of an agar plate with a ‘cross’ of tape merely wastes tape and may interferewith the viewing of the plate’s contents. Before incubation is complete, an agar plate must never be sealed completely by tapingaround the circumference; this will create anaerobic conditions which may prevent the normal growth of microbes or isolateanaerobes which may be pathogenic. If there is reason to suspect that an incubated plate may contain unknown species (whichmay be pathogenic), for example when sampling from the environment, it is sensible to seal plates completely just before they arereturned to student

Microbiology: an HMI Guide for Schools and Further Education (HMSO 1990, now out of print), Topics in Safety (ASE 1988, 2001), CLEAPSS Laboratory Handbookchapter 15.2, 15.12 (CLEAPSS 2001), Safety in Science Education(DfEE; HMSO 1996) and Biology/Biotechnology Safety in Microbiology: A Code of Practice for Scottish Schools and Colleges(SSERC .