Incubation conditions used for studying biodegradation of fibers and films

3 Incubation conditions used for studying biodegradation of fibers and films 

In the enviromnent, fibers or textiles can find their way into aerobic or anaerobic environments. Many aquatic environments and the top few centimeters of soil contain sufficient O2 to be aerobic. In contrast, anaerobic conditions exist in the deeper soils, water-logged soils, aquatic sediments, and landfills. Thus, biodegradation studies have assessed the fates of fibers and textiles under aerobic and anaerobic conditions. 

One of the simplest methods for aerobic culturing (if carbon dioxide is not collected) is to add the fiber or film and the microbial inoculum to a container with liquid medium. This is covered in some manner to allow air to get into the container while preventing foreign microorganisms from contaminating the culture system this is typically achieved by means of a sterile foam plug in the neck of the container. The container may be placed on a rotary shaker to increase the rate of aeration. However, if the depth of 

The methods required to create and maintain conditions that are suitable for growing anaerobic cultures are more difficult than those required for culturing aerobic cultures. Nonetheless, use of methods such as the serum bottle modification of the Hungate technique [24] is now routine in many laboratories. As discussed in the previous section, the formulation of the medium depends on whether the fiber or fabric is to serve as the sole source of carbon, nitrogen or sulfur. In addition, the formulation of the anaerobic culture medium depends upon which terminal electron acceptor is to be considered in the study. As shown in Table 1.2, the list of terminal electron acceptors includes Mn(IV), nitrate, Fe(III), and sulfate. In addition, bicarbonate (carbon dioxide) serves as the terminal electron acceptor for methanogenesis (equation 1.1). Supplementing the medium with an abundant supply of one of the terminal electron acceptors prescribes the microbial process that occurs in the cultures. Fermentation, in which some oxidized organic compound serves as the terminal electron acceptor, also occurs under anaerobic conditions. 

In a pure-culture study, Janssen and Schink [33] elucidated the pathway for the depolymerization and subsequent fermentation of poly(3-hydroxybutyrate) by Ilyobacter delafieldiv, the products of fermentation were acetate, butyrate, and H2, with a molar ratio of acetate butyrate of 2.32 1. In a co-culture of I. delafieldii and ihe H2-consuming, sulfate reducer Desulfovibrio vulgaris, the molar ratio of acetate butyrate changed to 4.02 1. Accordingly, the amount of H2 detected in the co-culture was much lower in the presence 

---