I strongly believe that the antagonistic property is not based on biochemical compounds but rather due to intrinsic and inherent factors such as; the possession of resistance plasmid (genome based), pumping action capability or the ability to secrete degenerative enzymes, in the case of antibiotics or perhaps, high capacity for mutation or even lack of cell wall in the case of Mycoplasma bacterium or thin cell walls in the case of Gram-negative bacteria.

I agree with Oludayo Oduwobi! Antagonistic is a broad and can be a not narrow topics.

Instead I would recommend looking into what antagonistic factors specifically you are wanting to look into such as antibiotic resistance, transport, receptors, or metabolic pathways.

Once you have an idea of what factors you want to look into you can find tools to help you answer your question

In addition to what Mr Oludoya Oduwobi said, there are several factors that contribute to the antagonistic properties of a bacterium. Bacteria can form biofilms, which are communities of bacteria adhered to a surface and enclosed in a protective matrix. Biofilms can act as a barrier against other bacteria, preventing their growth or inhibiting their movement.

Some bacteria are also capable of producing antibiotics that can selectively inhibit or kill other competing bacteria. This provides the producing bacterium with a competitive advantage for resources and survival.

It's important to note that antagonistic properties can vary depending on the specific bacterium and the environment it inhabits.

Dear colleagues, the author of the question talks about the presence of bacterial metabolites that inhibit other microorganisms. This does not talk about bacterial resistance to antibiotics, for example.

Ms. Vaitiekunaite, I think you can treat the metabolites of this bacterium with a cocktail of proteases or boil it to get rid of the possible effect of antimicrobial proteins such as bacteriocins, neutralize the pH value with an alkali or acid, and so on. Using the method of exclusion, you will determine to which group of substances the cause of antimicrobial activity can be attributed. You can do this yourself. And then you can turn to specialists in a specific field.

Bacterial metabolism is abroad term,fist of all put your isolate on group of classification according to Bergy .manual for clssifactin of bacteria

A variety of techniques and approaches can be used to identify the biochemical compounds responsible for the antagonistic properties of bacteria.

Here are some commonly used methods; Fractionation by bioassay, Mass spectrometry-based metabolomics, Genome Analysis, Chemical extraction and fractionation , and Structural elucidation.

Dear Dr. Doroteja!

HPLC is considered as precise and widely acceptable mehod for detection&identification of metabolites. You can search for the analytical laboratories equipped with this machine in your region (e.g. Universities , Research Centers, etc.) and discuss with them protocols and prices because they might be different depending on many factors.

Allow me also just to write some ideas which might be useful for you to find what compounds are responsible for antagonistic activities. These ideas might be also help you to facilitate your plans for HPLC assays.

The first one is check references of species your strains belong to. Likely, you will find manuscripts with already reported antagonistic compounds produced by this species, then you can try these protocols to detect these compounds in the supertanant/cells of your strains.

If you do not have an access to HPLC, you can also try to narrow the range of searching using methods of exclusion as suggested by Andrey Sgibnev. You can also try using different solvents i.e. obtain supernatant of your strain and use different solvents (e.g. methanol, ethyl acetate, etc.) to extract pull of compounds dissolveable in these solvents. Then, check these extracts for their antagonistic activities. If any of extract will have inhibition, at least you will get some information about certain properties (e.g. polarity) of your potential active metabolite. Please, make sure to apply all required safety rules working with extracts and solvents.

Another way is a quite long to describe, I tried to write as short as possible.

You can grow your potential biocontrol candidates in liquid media with different chemical composition, e.g. mediumA, mediumB, and mediumC. Then, obtain supernatant from these media and filter it to get rid of all bacterial cells . Important to check that these supernatant are sterile to make sure that any future observed antagonistic effect will be caused by supernatant, not by living culture if the cells will remain. Apply these supernatant on pathogen. If e.g. the supertanant from mediumA and mediumB will not affect its growth while supernatant from mediumC will inhibit it, it is logically that antagonistic compounds are presented in mediumC only. Then, check for companies or Institutes performing HPLC-MS measurements and discuss to analyse your supertanant from all 3 media for metabolic profiling. After you get them, compare profiles among 3 media and select the compounds with the remarkable quantity in medium C and absent/low quantity in media A and B. Those compounds (they can be not found in the databases) presuambly posess antagonistic properties because they are only in medium at remarkable C (which had antagonistic activity) and absent in media A and B (which did not have antagonistic activity). For further purification of these compounds you need to consult a chemist.

I hope some of the above will be useful for you, at least I hope you will get some ideas.

Good luck with your research,

Anuar.