Corynebacteria vs Clostridia

[miles500]

Hey,

I'm trying to understand corynebacteria a bit better as many environmental samples we get are gram positive rods and yet not identified as bacillus.

The gram stain of the majority of these samples fit the bill with corynebacteria ; clubbed cells, palisade arrangements, chinese letters and metachromic granules.

However I took about 18 of these samples and streaked them onto blood agar. After 24hrs the growth rates were very mixed. 3 had excellent growth and were all ID'ed as corynebacterium spp. The other 15 had very little growth and only one of these had enough growth for a full ID. This one came off as Clostridium.

Would the gram stains of corynebacterium and clostridium be at all similar? After reading up, Clostridium seems to be commonly be gram varible. This was definitely not the case in the gram stain.

Incubation was aerobic and at 35'C

Thank you for any help.

[JorgeLobo]

Gram stains of microbes from this environment are not definitive beyond + variable and -. By what criteria do you classify these as Corynebacteria - esp. vs Arthrobacter and the like? How do you rule out Bacillus spp.?

Generally - there culture conditions are a bit suspect. Blood agar and incubate at 35C are probably not appropriate for microbes from your soil.

[Sepals]

Corynebacteria have the characteristic Chinese lettering arrangement.

[JorgeLobo]

more than just the corynebacteria demonstrate that staining and corynebacteria are not defined by that pattern.

[Sepals]

Yes it does take more than Chinese lettering to identify the Corynebacteria, but the OP just asked about gram staining and it is characteristic of the species. Give me examples of other species which group in this manner.

[miles500]

Many thanks for the replies. I'm trying to validate some sort of genus level ID purely from gram check, morphology and a few selective agars and tests. I understand that this may not be practical so I can't emphasize enough that I'm purely researching.

So do you know what tests could ID a corynebacterium? Looking at the comments here and other places I've looked, a clubbed GPR could only really be described (or ID'd) as a coryneform, rather than any particular genus. Is there any other way to further narrow down the ID?

[JorgeLobo]

There are some good technical references - do a search on google scholar.

[Sepals]

I have and it all comes up with Corynebacterium.

http://scholar.google.co.uk/scholar?q=c ... art=0&sa=N

What are the names of other organisms which form this arrangment?

[JorgeLobo]

pretty sloppy to id by cellular morphology alone - esp. when you've never even seen it, sepal

[Sepals]

pretty sloppy to id by cellular morphology alone - esp. when you've never even seen it, sepal

Which is why i'm not iding it, I giving advice on gram strain as the OP asked. Look I'm really not interested in arguing with you, you seem bent on flaming me and I've seen you flame others. If you don't know about something, simply stay out of the thread rather than flame those who do.

[JorgeLobo]

I commented on your message - that is was Corynebacterium - not you. It is clearly misleading to offer taxonomy in the context of the tiny data offered, This was misleading - simple as that.

You do the original questioner a good turn if you provide perspective on how to proceed rather than guesshng.