Gut microbes why studies have different conclusions and which is more accurate

A study of the human gut performed in 1982 used various types of plates under different growth conditions to    describe and enumerate the microbes in the human gut. They concluded that the majority of the microbes in the    human gut are Gammaproteobacteria. A study conducted in 2010 using next-generation sequencing to    characterize 16S rRNA sequences concluded that the majority of the microbes in the human gut are Firmicutes    and Bacteriodetes. Why did these studies have different conclusions? Which study do you think is most accurate?