Phage Biology

T-even phage are especially virulent and are often found among phage selected for therapeutic purposes. Much is known about the molecular aspects of T4, but practically nothing is known about its growth physiology in the wild. Half of the genes in T4 have no known function in laboratory conditions, but may have functionality in their natural environments. T-even phage commonly exist in the mammalian digestive system, requiring anaerobic fermentation and/or respiration.

As a facultative aerobe E. coli has the capability to switch its metabolism in anoxic conditions to anaerobic respiration using an alternative terminal electron acceptor such as nitrate or fumarate. The organism can then still use the electron transport system (ETS). This study is the first to examine the ability of T-even phages to infect E. coli grown under anaerobic respiration conditions; nitrate was chosen as the electron acceptor.

T4 was included as the most extensively studied and fully sequenced, but it has a limited host range. Other phages were selected for their broad host range on the ECOR collection and on agricultural and clinical isolates. The bacteria used were B, ECOR4 and the sequenced K12 strain MG1655. We find that the patterns of infection are often substantially different under the various conditions. We see cases where phage infect efficiently aerobically but are unable to attach anaerobically (suggesting alterations in the surface receptors because of growth physiology). The kinetics of anaerobic infection are generally greatly prolonged, with lysis inhibition up to 27 hours as opposed to 3-5 hours seen aerobically. (In these cases, ability to lyse with chloroform demonstrates that all cells were productively infected early in this period.)

Total phage production and bacterial survivors were followed to document the ability of the virion to kill its host. In summary, we have shown that T-even phages have the ability to infect a variety of hosts anaerobically with minimum nutrient availability. Clearly, this aspect of phage biology is important as a preliminary to therapeutic usage as well as to better understand phage physiology in natural conditions.

Other Data Collected:
Topic (Complete): A04 Experimental Therapeutics Keyword
(Complete): bacteriophage; anaerobic Grant Request (Complete):

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Last Updated: May 29, 2008

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