minimal Illumina read length acceptable for microbial diversity analysis

Question

[Louis Kok]

Hi All. I have 16S amplicons for soil samples generated from HiSeq 2500 2 x 100bp paired-end library. I was wondering if it would be sufficient enough to perform the analysis using only R1 reads because R2 reads bases quality are very bad. My another question is, What is the minimal read length acceptable to perform alpha and beta diversity analyses for . Even thought the read length is 100 bp, it would become shorter after trimming the right end of the reads. Could you share with me your experience in handling the data? Thanks in advance.