Pic of Girl . sub full of virgins . TO THE FRONT PAGE ! !!<| sep |> There are a few things going on in your question that reflect a little confusion . The first is that lignin does decompose , and it does so even absent microbial action . When lignin is buried , pressure and temperature increase and the lignin breaks down . This general process is called diagenesis . In fact our understanding of lignin diagenesis is central to our assessment of fossil fuel reservoir quality . One of the things that lignin makes when it decomposes is called vitrinite , which reflects light . By measuring the vitrinite reflectance , it ' s possible to know how the thermal history of a basin , which tells you the quality of coal , oil , gas , and kerogen you can expect . Crude oil is similarly complicated . Crude oils come in a wide range of complex chemical mixtures , but all of them contain different proportions of alkanes , cycloalkanes , asphaltenes , and aromatic hydrocarbons . They can be classified in an astonishingly detailed way . sweet , sour , light , heavy , and then a series of designations that reflect where an oil of that particular chemical composition was found . But there are plenty of bacteria that can eat them , mainly Vibrio and Pseudomonas species . Fungi are also incredibly good at digesting the compounds found in crude oil . Fungi are like the Mr . Fusion on the back of the back to the future car . they can run on damn nearly anything . The thing is , it ' s a fairly slow process , which is why bioremediation of the oil spill in the Gulf of Mexico isn ' t an overnight thing . Graphite is the stable phase of carbon over a huge range of temperatures and pressures , and I don ' t know of any microbe that eats it . Of course , graphite is not inert , so it does react particularly with oxygen . Plus some might argue it ' s not organic , so who knows .