Production of tetrapyrrole compounds and vitamin B12 using genetically engineering of Propionibacterium freudenreichii. An overview Yoshikatsu Murooka, Yongzhe Piao, Pornpimon Kiatpapan and Mitsuo Yamashita Lait, 85 1-2 (2005) 9-22 DOI: 10.1051/lait:2004035