hep1487

I am in a summer microbiology class that only meets once a week. We were given a random unknown bacteria and have to figure it out. The possibilities for this random bacteria are 1. Eschericia coli2. Enterobacter aerogenes 3. Staphylococcus epidermis 4. Streptococcus salivarius 5. Clostridium sporogenes 6. Serratia marcescans 7. Kocuria rosea 8. Klebsiella pneumoniae 9. Mycobacterium smegmatis 10. Proteus mirabilis 11. Proteus vulgaris 12. Sarcina lutea 13. Pseudomonas aeruginosa 14. Lactobacillus acidophilus After doing a Gram stain and observing it under the microscope I discovered my unknown bacteria is Gram positive and bacilli. Knowing this narrowed my possibilities down to Clostridium Sporogenes, Mycobacterium Smegmatis and Lactobacillus Acidophilus. I then learned Mycobacterium Smegmatis does not stain well with Gram stain (correct?) so I removed this from my possibilities as well. My teacher gave us different tests to do depending on if the bacteria was Gram negative or positive. The tests I did on my bacteria were PRL (phenol red lactose),PRS (phenol red sucrose), PRD(phenol red dextrose), citrate broth, MSA (mannitol salt agar), and EMB. I was supposed to do TSI but some things were unlabeled and accidentally did EMB instead of TSI so that result is pretty irrelevant. My results: PRL- negative PRS- negative PRD- positive citrate- positive MSA- growth but no color change (halophile) I thought both possible bacteria would ferment lactose, sucrose and dextrose so this may be a mistake and I may redo my tests but my teacher says I do not need to and I should be able to figure it out. I also think Lactobacillus Acidophilus would not have a positive result in the citrate broth so that leads me to believe my bacteria is Clostridium Sporogenes but why wouldn't it ferment the lactose and sucrose?