One aspect of the present disclosure relates to a stabilized recombinant expression plasmid vector comprising a polynucleotide encoding an antitoxin gene which expresses a polypeptide that neutralizes a polypeptide toxic to a host cell, the toxic polypeptide being expressed by a toxin gene in the host cell, and a polynucleotide encoding a polypeptide expression product, and the stabilized recombinant expression plasmid vector is derived from a Hafnia alvei autonomously replicable backbone plasmid. Other aspects of the present disclosure relate to a transformant transformed with the stabilized recombinant expression plasmid vector disclosed herein, a method of producing biobased cadaverine using the transformant disclosed herein, and biobased cadaverine prepared by the method disclosed herein. Another aspect of the present disclosure relates to a polyamide formed using biobased cadaverine disclosed herein, and a composition thereof. Another aspect of the present disclosure relates to a method of preparing 1,5-diisocyanatopentane comprising preparing biobased cadaverine using the method disclosed herein and converting the biobased cadaverine to 1,5-diisocyanatopentane.