Alcaligenes faecalis - Grade: B+ PDF

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La Guardia Community College

UNKNOWN #13C

Alcaligenes faecalis

Microbiology 2010

Professor O. Calderon

Alcaligenes faecalis

Unknown # 13C I began my unknown determination with gram staining and my specimen reveals a Gramnegative bacteria. My problem was the morphology. The specimen were so small that the first time I saw it in the microscope , I knew it was cocci but then some look like bacilli. I did the negative staining to verify and I got the same result: mostly cocci and a few bacilli. My first initial tests were Thioglycolate, Glucose and TSA Agar plates to determine if my specimen is aerobic or anaerobic as well as which is the optimal temperature it would grow. I inoculated my media and placed in both in aerobic and anaerobic conditions. After approximately 48 hours I came back to the lab to check on any growth and my cultures gave me some good results. TSA Agar plate had a growth in aerobic condition and no growth in anaerobic conditions. With the Thioglycolate result, I concluded that I have an obligate aerobe bacteria. My glucose broth tests revealed that my specimen‘s optimal temperature was 20-37 o C. No growth on the 4o C and 55o C tubes. I did the Oxidase test with my TSA agar plate and the bluish-black color revealed an oxidasepositive bacteria. My Carbohydrate Fermentation test also revealed a negative result. I also got a positive Catalase result. With my initial results, while checking the flowchart in the lab manual, I thought I already know my bacteria, which is the Pseudomonas aeruginosa. I almost stop there thinking that I was lucky to have an unknown which was easy to uncover. Checking the Bergey’s Manual I decided to do more test to confirm the identification of my bacteria. That’s when I got the stress of my life when my bacteria tested negative on the Nitrate Reduction test. P. aeruginosa is positive on that test. And worst, I overlooked the green-pigment that the P. aeruginosa should have. My bacteria was not what I think it was. The next laboratory period was a busy day for me because I had to do more tests: Starch hydrolysis (-), MacConkey (-), Esculin (-), Citrate (+), Urease (-), Indole production (-), MR (-) VP (-), and motility (+). I also decided to do the gram staining again and this time I thought I got a gram-positive stain. I thought there was no way that I have a negative stain because there’s no bacteria that is gram-negative cocci aside from the Pseudomonas that will fall in the list of unknowns. With all of my initial test results I concluded that it could be Micrococcus luteus. But then I decided to do EMB (Eosin Methylene Blue) agar and MSA (Mannitol Salt Agar) test to confirm if my bacteria is positive or negative. So I inoculated my specimen in those media. I also did the antibiotic sensitivity test. Next lab period was a beautiful day. I finally confirmed that my unknown bacteria is a gramnegative bacteria when it grew on the EMB plate and not on the MSA plate. Based on the Bergey’s Manual of Determinative Bacteriology, all of the test results were confirming that my unknown bacteria is Alcaligenes faecalis.

Alcaligenes Faecalis

In TSA : white colonies and non pigmented

Oxidative-fermentative test with glucose: NEGATIVE

Genus Alcaligenes Rods, coccal rods, or cocci, 0.5-1.0 x 05-2.6 , usually occur singly. Resting stages are not known. Cells stain Gram negative. Motility occurs with 1-8 (occasionally up to 12) peritrichious flagella. Obligately aerobic, possessing a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Some strains are capable of anaerobic respiration in the presence of nitrate or nitrite.

Optimum temperature is 20-37o C.

Colonies on nutrient agar are

nonpigmented. Oxidase positive and catalase positive. Indole is not produced. Cellulose, esculin, gelatin, and DNA usually are not hydrolyzed. Chemoorganotrophic, using a variety of organic acids and amino acids as carbon sources. Alkali is produced from several organic salts and amides. Carbohydrates are usually not utilized. Some strains produce acid from D-glucose and D-xylose and utilize both carbohydrates as carbon source. Occur in water and soil. Some are common, apparently saprophytic, inhabitants of the intestinal tract of vertebrates. Numerous strains have been isolated from clinical material such as blood, urine, fees, purulent ear discharges, spinal fluid, wounds, etc. Occasionally, cause opportunistic infections in humans.

Type Species: Alcaligenes faecalis

Bergey’s Manual of Determinative Bacteriology

Scientific classification. Kingdom

:

Bacteria

Phylum

:

Proteobacteria

Class

:

Beta Proteobacteria

Order

:

Burkholderiales

Family

:

Alcaligenaceae

Genus

:

Alcaligenes

Species: Alcaligenes faecalis Alcaligenes faecalis is a Gram-negative, rod-shaped, motile, non-nitrate reducing, oxidase positive, catalase positive, and citrate positive obligate aerobe that is commonly found in the environment. It was originally named for its first discovery in feces, but was later found to be much more common in other places as well. Optimum growth occurs at about 37° C with no pigmentation. While opportunistic infections do occur, the bacterium is generally considered non-pathogenic. When an opportunistic infection does occur, it is usually observed in the form of a urinary tract infection. The bacterium degrades urea, creating ammonia which increases the pH of the environment. Although A. faecalis is considered to be alkaline tolerant, it maintains a neutral pH in its cytosol to prevent the damaging or denaturing of its charged species and macromolecules. A.faecalis has been used for the production of non-standard amino acids. A. faecalis is normally found in soil, water, and environments in association with humans.

(Wikepedia) http://en.wikipedia.org/wiki/Alcaligenes_faecalis

GRAM STAINING

+

-

+ B. cereus B. subtilis B. stearothermophilus B. megaterium L. brevis C. sporegenes C. perfringens

-

Cocci

Bacilli

S. aureus S. saprophyticus S. epidermidis E. faecalis L. lactis S. agalactiae S. salivarius M. luteus M. roseus M. varians

none

A. faecalis C. freundii E. aerogenes E. coli P. vulgaris P. mirabilis P. aeruginosa P. fluorescens S. marcescens

Oxidase

-

+ Glucose Oxidized

+

Acid and Gas from Lactose

o

Growth at 40 C

White colonies

Yellow colonies

Alcaligenes faecalis

Appendix H Johnson, T and Case, C. 2010. Laboratory Experiments in Microbiology (9th Edition)...