Final answer:
While aerobic degradation is common for chlorinated xenobiotics, anaerobic microbial bioremediation is also possible for these compounds, and strict anaerobes can use anaerobic respiration or fermentation to degrade pollutants.
Step-by-step explanation:
The claim that chlorinated xenobiotics can ONLY be degraded aerobically, thus making them very recalcitrant in anoxic environments is not entirely accurate. Although aerobic degradation is a common and often efficient pathway for the breakdown of these compounds, some microbial bioremediation strategies can employ anaerobic processes. Microorganisms have been known to use various metabolic pathways to degrade pollutants, including those that function in the absence of oxygen. For example, strict anaerobes can metabolize substances through pathways like anaerobic respiration or fermentation. Furthermore, certain conditions might enhance the bioremediation process, such as the addition of inorganic nutrients to promote bacterial growth. Successful biodegradation of pollutants like chlorinated xenobiotics may involve a combination of both aerobic and anaerobic microbial processes.