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).
Thank you.
Talking of past publications, I would use the past tense, as you did. That is if I don't have to follow a specific style, or I am not supposed to write how a specific style manual tells me.
Notice that in your last sentence you are using the passive voice, when you should use the active voice.
Further, these publications mainly used morphology and molecular data as the basis of identification (2011).
The tense used is less important than being consistent. Another important consideration is eliminating the inevitable verbosity and awkwardness of biomedical English. Sometimes the latter is difficult to do without a major rewrite, but what I've given you below is much better than the original. I'm not claiming that it's perfect or beautiful, just briefer and clearer, both pluses for biomedical readers.
More than 20,000 bioactive metabolites are of microbial origin (Berdy 2005). From 2007 to 2010, only about 200 articles on endophyte diversity were published, and most of them used morphological and molecular data to identify the metabolites ([AUTHOR NAME] 2011).
I wouldn't use present tense here unless you're about to review those 200 articles. But it really doesn't matter unless the journal's style manual states a preference or requirement for past or present tense.
