Microbiology lab report for undergraduated university level

Aim : Identification of Ba (Pommerville )cteria

Abstract

Identification of microorganisms through biochemical analysis is a crucial step in identifications of the unknown bacterium (Pelczar . This work of identification of bacterium was performed through different biochemical tests . Unknown cultures were streaked on EMB , SS and MacConkey agar plates to distinguish the lactose and lactose non-0feremnetros and to identify the grams nature of the culture . The culture was also streaked on TSI agar slants to confirm the cultures ability to switch n from glucose to lactose and sucrose

Performing the biochemical tests

for the given bacterium it is confirmed that the cultures provided were Gram-negative E .Coli Gram-negative paracoliform Yersinia enterocolitica and Gram positive Bacilli

Introduction

Microorganisms are omnipresent , and plays crucial role in biogeochemical cycles . In human perspective they are classified as pathogenic (disease causing ) and non pathogenic organism (Pommerville Once pathogenic organism succeeds to colonize in side the body it starts exerting its effect by interfering normal metabolic processes . In most of the infection there are specific symptoms associated with it but in certain cases it is difficult to distinguish two types of infection causes by two different organisms and in this case detail microbiological investigation is needed to identify causative agent and than its cure (Pelczar . There are different ways by which one can identifies particular organism like based on its morphology , Staining behavior , air requirement for respiration , substrate utilization etc termed as biochemical test . Here we have performed various biochemical tests for identification of given gram positive and gram negative organisms

Materials and methods

The given cultures were streakek on . TSA , Blood agar and Maconkey agar plates and incubated at 37 ? C

After incubation plates were observed for growth and results were noted down

Single colony were picked up and used to prepare smear for gram staining

Based on results of gram staining cultures were classified as Gram positive and Gram Negative

Based on results of initial streaking and gram 's staining cultures were inoculated in different selective or differential media for further identification

Hemolytic , gram 's positive cocci was inoculated to differential media namely mannitol salt agar to distingsh between streptococci and staphylococci

Similarly for catalase assay , single colony from positive blood agar plate was used to make smear on glass slide . The smear was overlaid by H2O2 and observed for bubble formation

Isolated colony was picked up from MacConkey agar plate and streak on to the EMB ,TSI slant and SS slants ( streaking and stub culturing

Similarly , isolated colonies from all three plates were streaked on galantine , starch , casein and citrate containing plates to determine gelatinase , amylase , proteases and citrate utilization capability of organisms

All the plates and slants were incubated at 37 ?C

After incubation plates and slants were taken out and results were noted for

positive and negative results

Based on standard result chart unknown organisms ware identified

Flow chart or tests

Results

Culture 1 : The culture displayed negative for caseinase , amylase and gelatinase . On EMB medium colonies appeared blue-black with metallic green sheen...