Microbial Culture Media PDF

MICROBIAL CULTURE MEDIA COMPOSITION OF CULTURE MEDIUM Nutrients Energy source Essential metals and minerals Buffering agents Indicators for pH change Selective agents Gelling agent CLASSIFICATION OF CULTURE MEDIA Classification based on physical state Solid med...

MICROBIAL CULTURE MEDIA COMPOSITION OF CULTURE MEDIUM Nutrients Energy source Essential metals and minerals Buffering agents Indicators for pH change Selective agents Gelling agent CLASSIFICATION OF CULTURE MEDIA Classification based on physical state Solid medium semi-solid medium liquid medium Classification based on nutritional factors: Non synthetic media Synthetic media Classification based on function (or the purpose of using) General purpose media, Enriched (complex) media Selective media Differential media Transport media Anaerobic media Assay media CLASSIFICATION OF CULTURE MEDIA BASED ON PHYSICAL STATE 1. Solid media Agar is used to make a liquid medium into a solid. Sphaerococcus euchema Agar is obtained from sea weed e.g Sphaerococcus euchema, Gelidium corneum Agar is a solid until it reaches boiling temperature. Gelidium corneum At boiling temperature, it dissolves in water and remains in the dissolved state until temperature falls to 40-42oC. Below 40-42oC, it solidifies again. It must reach boiling temperature before it melts again. CLASSIFICATION OF CULTURE MEDIA BASED ON PHYSICAL STATE 2. Semi-solid medium (agar = 0.5%) Media is soft Used for demonstrating bacterial motility and separating motile from non-motile 3. Liquid medium (agar = 0%) Also referred to as broth Bacteria grow uniformly CLASSIFICATION BASED ON NUTRITIONAL CONTENT 1. Non synthetic media contains ingredients that are not chemically defined or pure e.g animal extract Complex media Medium constituents are not totally known and may even vary in composition e.g. beef extract, yeast extract, peptone, etc. 2. Synthetic media consists only of known mixtures of chemical compounds - such as glucose, inorganic salt phosphate for E. coli Defined medium Types of chemicals and their concentrations are known. CLASSIFICATION BASED ON FUNCTION 1. General purpose media: Growth of all microorganisms e.g nutrient agar, nutrient broth 2. Enriched media Additional substance like blood, egg yolk are added to the basal media Suitable for growth of fastidious microorganisms E.g. chocolate agar, blood agar 3. Enrichment medium Medium which encourages the Growth on nutrient agar growth of one organism or group of organisms while minimizing the growth of others. e.g. lactose broth encourages enteric microorganisms to flourish. CLASSIFICATION BASED ON FUNCTION 4. Differential medium growth of a specific microorganism or a group of microorganisms with visible changes in the appearance of the medium. ▪ e.g. MacConkey agar MacConkey agar 5. Selective medium medium, with one or more chemical inhibitors in it. It allows the growth of the resistant organism while preventing the susceptible organisms. ▪ e.g. Mannitol salt agar. Mannitol salt agar.  CLASSIFICATION BASED ON FUNCTION  Differential and selective media Some media can be both differential and selective. e.g. SS agar, MacConkey agar, EMB agar, Hektoen enteric agar, Mannitol salt agar MacConkey agar ▪ Selectivity - Crystal violet dye and bile MacConkey agar salts halt the growth of gram-positive bacteria ▪ Differential – based on lactose fermentation Mannitol salt agar ▪ Differential ingredient - sugar mannitol. ▪ Selectivity - 7.5% NaCl (salt) Mannitol salt agar EXAMPLES OF SELECTIVE/DIFFERENTIAL MEDIA CLASSIFICATION BASED ON FUNCTION 6. Transport media useful for clinical specimens maintain the viability of potential pathogens Example: ▪ Pike’s media ▪ Sach’s buffered glycerol saline 7. Anaerobic media Ideal for anaerobic bacteria which require low oxygen levels 8. Assay medium (Microbiological assay culture medium) It’s used for amino acids, vitamins, and antibiotics assays. ESSAY WRITING  Title  Introduction  Body  Conclusion  LAB REPORT WRITING  Title  Introduction  The introduction should state your overall aim and give a brief background information about the theory and method done in the practical.  Materials and Methods  Report on the method used or the steps taken, with any precautions, include a list of materials, diagram(s), especially of non-standard equipment  Results  Display the data in Tables or graphs as appropriate and describe the results in words. Give an example of the calculation used. This section should be written using paragraphs NOT using point form. Materials used should NOT be listed. LAB REPORT WRITING  Discussion  The discussion addresses the trends arising from each and every table (refer to tables/figures in your results. e.g. According to table 1 ………..  Explanation should be given for each trend.  Compare your results with results from similar studies that have been carried out.  Any recommendations on how the practical may be improved should be outlined.  Conclusion  A conclusion should be made looking at whether the results concur/contradict your hypothesis  Do not introduce any new ideas here LAB REPORT WRITING  References  Use the APA referencing style and be consistent throughout  Sources should be listed in alphabetical order.  More than 3 references are warranted for each lab report.  Sources to be cited  Journal articles  Books  Banned sources  Websites LAB REPORT WRITING Citation  One author Beginning of sentence: Surname (Year of publication)  eg Moat (2013) defines microbial physiology as the way microbial cell structures function End of the sentence: (Surname, year of publication) e.g Microbial physiology deals with the way microbial cell structures function, growth factors, metabolism and genetic composition of microorganisms (Moat, 2013) o Two authors Beginning of sentence: Surname of the first author and surname of the second author (Year of publication) E.g. Moat and Gilbert (2013) define microbial physiology as the way microbial cell structures  LAB REPORT WRITING  More than two authors Beginning of sentence: Surname of the first author et al (Year of publication) E.g. Moat et al (2013) define microbial physiology as the way microbial cell structures REFERENCING Journal articles Surname of author, Initial(s). (Year of publication). Title of journal article, Name of the journal (italized/ underlined), volume number (Issue number), page numbers. e.g Hamad, S.H., Al-Amer, J.J. and Al-Otaibi, M.M. (2013). Assessment of the microbiological quality and wash Treatments of Lettuce Produced in Hofuf City, Saudi Arabia, Asian Journal of Plant Pathology, 7(2), pp. 84-91. Books Surname of author, Initial(s). (Year of publication). Title of book (italized/ underlined), edition, Publisher, City of Publication, Country of publication. eg Moat, A.G., Foster, J.W. and Spector, M.P. (2002). Microbial Physiology, 4th edition, Wiley and Sons, New York, USA.