Biphenyl-utilizing bacteria

Recent developments involve utilization of cyclodextrins that are absorbed only in minor quantities in the small intestine but are fermented by the colonic bacteria. In a recent study [56,57], the use of biphenyl acetic acid conjugates of P-cylcodextrins was described. The ester conjugate released the drug preferentially when incubated with rat cecal contents, and almost no release was observed on incubation with the contents of the stomach or the small intestine. 

It has been observed that the incorporation of lipophilic chains into vancomycin can increase the potency of the dmg [159,160,161,162]. This is best exemplified by the observation that teicoplanin retains activity against some vancomycin-resistant bacterial strains. In one early study directed at improving the efficacy of these antibiotics, Ge et al. investigated the mechanism of action of a chloro-biphenyl derivative of vancomycin that showed activity against resistant bacteria [163]. The sulfoxide method of glycosylation was utilized to achieve the desired modification of the gluco-vancomycin precursor (O Scheme 28). 

Some examples for PAH compounds suggest that decreased solubility and non-aqueous-phase partitioning and sorption processes are restrictive toward microbial degradation. Wodzinski and Bertolini (16) and Wodzinski and Coyle (17) concluded that bacteria utilize naphthalene, biphenyl, and phenanthrene as dissolved solutes, with the rate of biodegradation independent of the total amount of solid-phase hydrocarbon. Stucki and Alexander (18) found that the dissolution rate of phenanthrene may limit the biodegradation rate. 

The ubiquitous occurrence of bacteria, which can utilize biphenyl as a sole source of carbon and energy, has been reported. Several species of Gram-negative and Gram-positive bacteria have been shown to degrade biphenyl and PCBs. The main pathway for biphenyl catabolism is outlined in Figure 3 [58-66]. 

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