It's tough to make solid recommendations without knowing either the specific gram-positive organism or the specific metabolite.

As a general recommendation, I would suggest bead beating the bacteria with sterile 0.1mm glass beads prior to the extraction (either via a specific bead beater or in a pinch just by vortexing vigorously). This will mechanically disrupt the cell walls. Alternatively, you can consider lysozyme for enzymatic weakening of the walls. If the cell walls remain intact it may interfere with your extraction. Depending on the metabolite (and the pH of the solution), small molecules may decompose or not extract well with acids or alcohols. Good luck!

I agree with Andrew - breaking the cell walls may be the best way to ensure extraction of intracellular compounds. In addition to the methods he mentions, you may also want to consider either a French press or sonication to disrupt the cells.

First of all thanks to both.

I am working with Enterococcus faecalis and i have to measure glycolytic metabolite Pyruvate in the log phase immediately after removing them from culture. 

The cell walls of E. faecalis should be relatively straightforward to disrupt with bead-beating or lysozyme treatment. French press is typically more effective with gram negatives although it may work here as well. Sonication would be effective for disrupting the membranes but has variable activity with gram positives due to the thick wall (unless you add lysozyme first, in which case absolutely it should be very effective).

I might consider the following protocol to disrupt the cells and clean up / concentrate the intracellular components, likely including pyruvate. It is designed for chromosomal DNA extraction but should extract most water-soluble metabolites as well. The addition of SDS should help disrupt membranes while the bead beating should disrupt the cell wall, both resulting in increased yield of intracellular components. You can also concentrate your sample depending on how much Tris buffer you use. I will note, however, that I've never isolated pyruvate myself so this is more of a "see if it works" than an established pyruvate purification protocol:

Start-to-finish, about 30 minutes with cheap reagents many labs already have on-hand (if it works!). Good luck!

Thanks for suggestion. I will try with this.