Although bacteriums is microscopic in size. it is mostly of import in the healthcare field. environmental work. nutrient readying. every bit good as many other industries. In peculiar. it is indispensable that healthcare workers be able to place the species of bacteriums occupying a human reservoir in order to order the right antibiotic that will kill that species. For the intent of bacteriums designation. legion trials have been devised to happen out the exact species in inquiry. However. because new strains continue to emerge. it is of the extreme importance that microbiologists and microbiology pupils understand the nature of each bacterial species and how that species creates and maintains its complex communities. Of equal importance is the speedy designation of the polluting beginning. The intent of this survey is to place an unknown bacteria utilizing as few trials as possible. and detect its importance in the universe at big. Materials and Methods
To get down this survey. a angle of bacterium was given by the teacher labeled “unknown 1. ” From this civilization. three T-streak home bases were aseptically inoculated and one was placed in a 37 grades Celsius brooder. one was placed in a 25 grades Celsius brooder ( to look into for optimum turning temperature. every bit good as pureness of the civilization ) . and the other was placed in a gas pak pouch. A reserve civilization was besides made which replaced the working angle after 21 yearss of usage. After the civilizations had incubated for 2 yearss and tried pure. a Gram discoloration was performed from the working angle. and an oxidase trial was performed utilizing a TSA home base. The gas pak system was used by making an inoculated TSA home base ( utilizing sterile techniques ) and puting it in a GasPak pouch. A bring forthing package was placed inside the GasPak pouch and the pellet attached to the pouch was observed for a white colour. bespeaking that O was absent. The GasPak was so placed in the 25 dgerees Celsius brooder for 48 hours and observed for growing. The Gram discoloration was accomplished by fixing a smear and using crystal violet to it. and leting it respond for 2 proceedingss.
The crystal violet was so washed off by force outing H2O onto one terminal of the slide. leaning it and leting the extra violet colour to rinse off. The slide was so flooded with Gram’s I and allowed to respond for 1 minute. 30 seconds. The slide was so rinsed once more with H2O utilizing the same technique as earlier. nevertheless this clip the extra H2O was shaken off. The following measure was leaning the slide at an angle ( hot Canis familiaris manner ) and adding acetone-alcohol one bead at a clip until the the colour came away. It was so important to wholly rinse the slide with H2O. After the slide was rinsed. it was clip to add the saffranine to the slide. to which it was allowed to respond for 60 seconds. The extra saffranine was so tilted off the slide and washed with H2O. The slide was so allowed to dry. The oxidase trial was performed to happen out whether the unknown bacteriums had cytochrome oxidase in its negatron conveyance concatenation. This was achieved utilizing the TSA home base from the 37 grades Celsius brooder and streaking the bacterium onto an oxidase card utilizing a toothpick. The card was so observed for a bluish colour within a 20 2nd clip frame. The following trial performed was agitation of milk sugar.
In order to prove for lactose agitation. a tubing of phenol ruddy lactose stock was inoculated from the working angle and so incubated at 37 grades Celsius for 48 hours. After incubation. the phenol red lactose broth was examined for colour alteration. The 5th trial performed was to happen out if the unknown bacteriums could use citrate as its exclusive beginning of C. This was done utilizing an vaccinating acerate leaf and aseptically reassigning the bacterium into a angle of Simmon’s citrate agar by knifing the acerate leaf into the butt of the agar. so streaking it across the top of the agar as the acerate leaf was pulled out. The tubing was so placed in the 37 grades Celsius brooder for 48 hours. observed for a bluish colour. so placed back in the brooder for another 5 yearss and observed once more. The 6th and 7th trials performed was the agitation of saccharose and arabinose. This was performed by aseptically inoculating a tubing of phenol ruddy sucrose stock. and a tubing of phenol ruddy arabinose stock with the unknown civilization and incubating at 37 grades Celsius for 48 hours. After incubation. the two tubings were examined for colour alteration. The 8th trial was to happen out if the bacterium in inquiry had scourge.
The motility trial was performed by aseptically inoculating the unknown bacteriums into a tubing of TSA stock and leting it to incubate for 24 hours at 37 grades Celsius. After the TSA broth civilization had incubated. it was used to inoculate a tubing of motility medium S to the 3rd. The inoculated motility medium was so incubated at 37 grades Celsius for another 24 hours and observed for ruddy runs radiating from the stab line. The 9th trial was intended to happen out if the unknown bacteriums can bring forth acetoin which is the precursor to butanediol. The Voges-Proskauer trial was was performed by aseptically inoculating a tubing of MR-VP stock with the unknown bacteriums and incubating it at 37 grades Celsius for 5 yearss. The incubated tubings were examined for growing. After scrutinies were recorded. 1 milliliter of the inoculated MR-VP stock was transferred to a clean trial tubing and so one phial of reagent A was added. The mixture was so lightly shaken for 30 seconds before adding 5 beads of reagent B. This mixture was so aerated smartly for 30 seconds and so allowed to sit for 10 proceedingss. but was aerated often during that clip.
After the 10 proceedingss was up. the tubing was observed for a pink colour ( tap indicates a positive trial ) . The 10th trial was to happen out if the unknown bacteriums had the ability to bring forth cysteine desulfurase. which produces H sulphide from the amino acerb cysteine. This trial was performed by utilizing a Kligler Fe agar angle and an inoculating acerate leaf to aseptically knife a civilization of the unknown bacteriums into the butt of the angle. so streaking it across the top of the agar as the acerate leaf is pulled out. The inoculated Kligler Fe agar angle is so incubated at 37 grades Celsius for 48 hours. The tubing is so observed for darkening of the agar ( bespeaking a positive trial ) . The 11th trial was to happen out if the unknown bacteriums contained the enzyme tryptophanase. which gives the bacterium the ability to hydrolyse tryptophan into indole. pyruvic acid and ammonium hydroxide.
The indole trial was performed when a tubing of tryptone stock was aseptically inoculated with the unknown and incubated for 24 hours. After the tubing had incubated. 1 dropper full of Kovac’s reagent was added to the tubing. The tubing was so aerated and observed for a ruddy bed ( bespeaking a positive trial ) . The concluding trials were to find whether the bacteriums could ferment dulcitol and melibiose. The trial was performed by obtaining a tubing with a pellet incorporating dulcitol and phenol ruddy and another tubing with a pellet incorporating melibiose and phenol ruddy ( these are called a wee-tab ) . 0. 25ml of unfertile H2O was so added to each tubing and so vibrated until the pellets dissolved in the H2O. Both wee-tabs were so inoculated with a thick loopful of the unknown bacteriums and incubated at 37 grades Celsius for 30 proceedingss. observed. so incubated for another 5 hours 30 proceedingss and observed once more for a colour alteration. Consequences
Unknown 1 had the undermentioned morphology on a TSA home base: medium sized. smooth. round settlements that were off-white in colour. After finding that it was a Gram negative little rod that was a facultative anaerobe. an oxidase trial was performed to verify the household of the bacterium. The oxidase trial was negative. demoing that Unknown 1 belonged to the household Enterobacteriaceae. Table 1 lists all the trials that were performed. along with the consequences.
To detect the household of the bacteriums “Unknown 1” . a Gram discoloration was performed. Under 1000X magnification. the bacterium was pink and rod shaped intending it was a gram negative. B bacteriums. This eliminated all the Gram positive bacteriums every bit good as all the coccus bacterium which allowed for specific proving. After the find that the unknown bacterium was a gram negative rod. it was of import to happen out if it was aerophilic or facultative. The gas pak system resulted in a positive trial by demoing minimum growing on the TSA home base. This indicated that the unknown bacterium was a facultative anaerobe. intending it uses and prefers aerophilic respiration. but can besides exchange to fermentation when O is non present. In order to happen out whether Unknown 1 belonged to the household Enterobacteriaceae. Vibrionaceae or Pasteurellaceae. an oxidase trial was performed. A negative oxidase trial indicated that the bacteriums could non utilize cytochrome oxidase in its negatron conveyance concatenation. Because of the negative Gram staining reaction and a negative oxidase trial. it became known that this bacteriums belonged to the household Enterobacteriaceae. In an environment where O is non present. a facultative anaerobe will ferment sugar to bring forth ATP.
Because the phenol red lactose stocks remained ruddy. there was no acerb production to do the index to alter from ruddy to yellow. bespeaking a negative trial. The agitation or saccharose and arabinose were besides tested in the same manner. nevertheless the acid production caused by the bacterium interrupting down these two sugars resulted in both tubings turning yellow. bespeaking positive trials. Based on these trial all bacteriums that were able to ferment lactose were crossed of the possible species list. every bit good as those that could non ferment saccharose and arabinose. If a bacteria possess the enzyme citrase. it will be able to utilize citrate as its exclusive beginning of C. The bacterium in inquiry produced a positive citrate use trial. The positive trial indicated that this species of bacterium contains citrase and can change over citrate to pyruvate and carbon dioxide.
All bacteriums that did non incorporate citrase was crossed of the list of possible bacterium species. Scourge are excessively little to see utilizing a light microscope. so a motility medium was used in order to see whether this bacterial species can travel about. The ruddy runs radiating from the stab line indicated that the bacteria has flagella. Because the bacterium was so good distribute throughout the medium. it can be considered really motile. Based on the motility trial. all bacterium species that were non-motile were crossed off the designation list. The Voges-Proskauer trial is intended to place the tract in which a micro-organism agitations glucose. If the bacteria produces butanediol as an terminal merchandise. it undergoes butanediol agitation. Because Unknown 1 tested negative for this trial. it must ferment glucose by assorted acerb agitation. All bacteriums that could finish butanediol agitation were eliminated from possible species of bacteriums. Certain species of bacteriums will bring forth hydrogen sulphide from the amino acerb cysteine. This unknown species of bacteriums tested positive for H sulphide production. bespeaking it is capable of catabolising cysteine.
This is of import in certain environments when cysteine can be used as an energy beginning for respiration. Any bacteriums that could non utilize cysteine as an energy beginning were eliminated. The indole production trial was used to happen out if this species of bacteriums could hydrolyse tryptophan into indole. pyruvic adic and ammonium hydroxide. The ruddy bed at the top of the trial tubing showed a positive trial for the unknown species of bacteriums bespeaking that it possess the enzyme tryptophanase. All bacterial species that did non incorporate this enzyme were eliminated. Dulcitol agitation and melibose agitation were the concluding trials used to separate between the bacteriums that could ferment these sugars and those that could non. The ruddy coloured dulcitol wee check indicated a negative trial. while the xanthous melibose wee tab indicated a positive trial. This concluding trial showed that Unknown 1 was Citrobacter freundii. Below is a flow chart that lists all the bacteriums that were eliminated with each trial.