You can simply use formaldehyde for this purpose, it must be easily available in your lab. You can use cotton, keep it in petriplates and then pour directly formaldehyde in to it. Cotton should be properly wet with formaldehyde and keep petriplates open where ever u want in your lab for 24 hour atleast, close the lab area. After that u can use the lab.

Use formaldehyde for fumigation. Do it on rest days. An evening (saturday evening) before a rest day (Sunday), you can fumigate the whole area with formaldehyde and then close the lab. Very effective and good method for fumigation.

Nogia and Nahata, i am using this method - Formaldehyde and formaldehyde with KMnO4. there are many side effect of this method. so if i get anyother cheapest method for this.

Could someone enlighten me as to why formaldehyde is the chosen method since Krunal is using NON sporulating bacteria?

Since the bacteria you are mostly using are non-sporulating, you shouldn't need formaldehyde for decontamination. This is really unsafe to do so.

Perhaps, if I understand correctly, you could just use a disinfecting solution for non-sporulating bacteria. I don't think this method can be used for fumigation, but it is cheap and safe.