The present invention belongs to the field of microbiology, and particularly relates to membrane vesicles (MVs) isolated from bacteria, and an isolation and preparation system and method for the membrane vesicles, and applications of the membrane vesicles. The bacteria of the present invention comprise Gram-positive bacteria and Gram-negative bacteria. The invention uses ionizing irradiation to irradiate bacteria, and isolates and purifies the produced membrane vesicles. The membrane vesicles prepared can be used as a vaccine, a vaccine adjuvant and/or a pharmaceutical carrier. In addition, the present invention provides a biological composition comprising the membrane vesicles and inactivated bacteria. In addition, the present invention also provides a preparation system, and isolation and purification system for bacterial membrane vesicles and the corresponding method. The membrane vesicles obtained by using the system and method have high yield, high purity and easy to be industrialized.
