(Видно, сильнейший радиационный фон способствовал) гибели разлагающих органику микроорганизмов, (поэтому физическое тело не разлагалось, а превращалось в мумию). There are three main structures: фон способствовал гибели - enabled / promoted destruction (фон - a subject, способствовал - a predicate, гибели - an object, which depicts a consequence of radiation background) гибели микроорганизмов - bacterial desctuction, desctruction of bacterias / microorganisms микроорганизмов, разлагающих органику - bacterias / microorganisms which decompose organic matters (this is a present participle, pertaining to the noun "микроорганизмов")

The problem is in a participial clauseб where a main word is placed in its end. Russian language allows to place the object both before the participial clause (in this case the clause is embraced by commas) and after — like in this case, — and if it's at the end, there are no commas. Semantically both variants are equivalent: "микроорганизмов, разлагающих органику, ..." = "разлагающих органику микроорганизмов" The second case is much more difficult to read and understand.