Currently, most chemical products for our daily life are mainly derived from petroleum.  However, rapid increase in the petroleum consumption and the sequential greenhouse gas effects force us to search for the alternative sources for building-block chemical production.  Building block chemicals are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules.  Twelve building-block chemicals were identified, which can be produced from sugars via biological and chemical conversion.  They are 1,4-diacids (succinic, fumaric and malic), 2,4-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol.  More than half of these chemicals are the metabolites of common metabolic pathways, which have been being explored for the large-scale production by fermentation.  It is of the great interest for exploration of the bio-production of those uncommon building-block chemicals in nature or by means of genetic engineering.  Symbiotic microbes act as protectors by producing toxins to ward off herbivores or pathnogens, which may be able to produce some of those chemicals.  The importance of those building-block chemicals and the potential production in microbial systems will be discussed.