Volatile compounds microbial metabolites

Many microbial metabolites are volatile compounds and in terms of their sensory properties can be broken into two broad categories odorants and tastants (Table 1). Tastants include salty, sour, sweet, and bitter compounds such as amino acids, peptides, and sugars. Primary odorants typically are quite volatile and include carbonyl compounds, esters, and terpenes. There is considerable overlap between the two categories lactones, for example, have both taste and odor properties. In keeping with the theme of this symposium, volatile aroma substances will be the primary focus. 

Compounds 8-11 belonged to the bisabolane family of sesquiterpenes. Bisabolane sesquiterpenes are not typical microbial metabolites. Most compounds of this skeletal class have been isolated from numerous terrestrial plants, a basidiomycete [101], sponges [102-103], octocoral [104, 105], and red algae [106], To our knowledge there have been two reports of bisabolanes from fungi. The first report in 1989 was of a mycotoxin from Fusarium sambucinum [107], More recently, mass spectral analysis of the volatile constituents of toxigenic Penicillium roqueforti strains yielded P-bisabolene [108]. 

Lewisite in soil may rapidly volatilize or may be converted to lewisite oxide due to moisture in the soil (Rosenblatt et al, 1975). The low water solubility suggests intermediate persistence in moist soil (Watson and Griffin, 1992). Both lewisite and lewisite oxide may be slowly oxidized to 2-chlorovinylarsonic acid (Rosenblatt et al, 1975). Possible pathways of microbial degradation in soil include epoxidation of the C=C bond and reductive deha-logenation and dehydrohalogenation (Morrill et al, 1985). Due to the epoxy bond and arsine group, toxic metabolites may result. Additionally, residual hydrolysis may result in arsenic compounds. Lewisite is not likely to bioaccumulate. However, the arsenic degradation products may bioaccumulate (Rosenblatt et al, 1975). 

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