Russia is a growing market for Pakistani exporters. In 2009/2010 the export target of Pakistan was US$20 billion. As of April 2015, Pakistan's exports stand at US$29 billion. The following is a list of Pakistan's main trading partners as of JULY 2017. The following is a list of companies that have business ties with Pakistan. Cobalamin biosynthesis  Cobalamin biosynthesis is the process by which bacteria and archea make cobalamin, vitamin B12. Many steps are involved in converting aminolevulinic acid via uroporphyrinogen III and adenosylcobyric acid to the final forms in which it is used by enzymes in both the producing organisms and other species, including humans who acquire it through their diet. Cobalamin (vitamin B12) is the largest and most structurally complex vitamin. It consists of a modified tetrapyrrole, a corrin, with a centrally chelated cobalt and is usually found in one of two biologically active forms: methylcobalamin and adenosylcobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes that use it as a cofactor, whereas plants and fungi do not use it. In bacteria and archaea, these enzymes include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia-lyase, and diol dehydratase. In certain mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase. In humans, it plays essential roles in folate metabolism and in the synthesis of the citric acid cycle intermediate, succinyl-CoA. There are at least two distinct cobalamin biosynthetic pathways in bacteria:  Either pathway can be divided into two parts:  A further type of synthesis occurs through a salvage pathway, where outside corrinoids are absorbed to make B12. Species from the following genera and the following individual species are known to synthesize cobalamin: "Propionibacterium shermanii," "Pseudomonas" "denitrificans", "Streptomyces" "griseus", "Acetobacterium", "Aerobacter", "Agrobacterium", "Alcaligenes", "Azotobacter", "Bacillus", "Clostridium", "Corynebacterium", "Flavobacterium", "Lactobacillus", "Micromonospora", "Mycobacterium", "Nocardia", "Proteus", "Rhizobium", "Salmonella", "Serratia", "Streptococcus" and "Xanthomonas".