Bacterial total protein can be isolated with good yield by using Kit Method, B-PER from Thermoscientific. If you have a low budget, then you can perform sonication method for total protein extraction. The protocol contains in attached file is low cost one.

If you want impurities free with good yield then use B-PER (Bacterial Protein Extraction Reagent)

Good luck

You can apply two methods of protein purification  to get rid of impurities; for instance if you purified your specific product using affinity chromatography approach then you can use the gel filtration method as a second step of purification to make sure that your protein is pure.

Good luck

Protein extraction from the bacterial cell requires suitable

reagents and technique that can yield a better and efficient result. you can use the  protocol in attached file for better extraction, then you can apply affinity chromatography approach.

Good luck