What tense should be used in writing the previous researches? For the following example, which one should I revise? Or I could always use any tense although the research has passed?
More than 20,000 bioactive metabolites are of microbial origin (Berdy 2005).
Starting from 2007 to 2010 there were only approximately 200 publications on endophyte diversity. Further, these publications were mainly used morphology and molecular data as the basis of identification (2011).