ENVR103 – Environmental Isolate

Source and Data Summary

The teachers’ desk in Fisher Building laboratory 222.

Test Result Conclusion
Gram Stain Positive Gram Positive.
KOH3 – String Test Negative Gram Positive.
Motility Test Positive Not all moved, and they weren’t hyper motile.
Spore forming Test Negative Did not produce spores after stressing them at room temperature in dH20.
Optimum Growth Environment Parameters: Result Conclusion
Blood Agar (BAP) Heavy Growth
MacConkey Agar (MAC) Heavy Growth Able to ferment lactose.
Eosin Methylene Blue Agar (EMB Little Growth Able to ferment lactose.
Mannitol Salt Agar (MSA) No Growth Not able to ferment mannitol salt.
Temperature: Scale: 1-5, where 5 is most favoured with heaviest growth
6°C Very little
Room Temperature (ca. 20°C) 3 out of 5
30°C 4 out of 5
37°C 5 out of 5 Most favoured.
55°C No growth
Sodium thioglycollate Obligate Aerobe
Nitrate Reduction – NO3 → N2 Positive Nitite reductase.
Peptone Broth pH: 7.5-8 Not part of ammonification process.
Oxidase Test: Purple Produces oxidase = part of ETC.
Catalase Test: Created O2 gas Positive – indicates that it is an aerobe
Glucose Fermentation Test: Negative
Indole Production Negative Not able to degrade tryptophan
Methyl Red & Voges-Proskauer Negative
Citrate Utilization Positive Utilizes citrase as a carbon source.

Tentative Identification of Your Isolate.

After confusing attempts trying to identify the isolate with Bergey’s Manual of Determinative Bacteriology, a site namned: http://microbeid.com was used to narrow down the search for an identity of the isolate.

Using the data provided on the previous page, I entered and checked all tests conducted with either a ‘positive’ or a ‘negative’ and searched for an appropriate match. It is assumed that the isolate is from the genus Bacillus since it is rod shaped and not circular/ball shaped (cocci). However, some cocci species are elongated, and this could be a source of error, persuading a wrong choice of group to identify the isolate.

The output from the website looks like this: http://microbeid.com/pib/bacillus.php
Identification Results Table:

Taxa ID Score Modal Score ID Quality
Bacillus lentus 0.39208 0.04746 Poor Identification
Bacillus psychrophilus 0.25432 0.00253 Poor Identification
Bacillus sphaericus 0.20749 0.00391 Poor Identification
Bacillus badius 0.10035 0.02694 Poor Identification
Bacillus azotoformans 0.01319 0.00010 Poor Identification
ENVR103 Tests ENVR103 Results Bergey’s – Group 19 – Bacillus
KOH3 – String Test – (neg) Gram-positive Gram-positive
Shape Rod-shaped bacteria Rod-shaped bacteria
Environmental Preference Obligate aerobes Obligate aerobes
Catalase Positive Positive
Spore Forming Test Negative Positive

The isolate showed all these characteristics except the last step of forming spores. Bergey’s Manual, however, indicates that Bacillus tend not to form spores easily. A spore forming test at a higher temperature (75-80°C) should be conducted to determine if it in fact is a Bacillus.

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