Marine environments were investigated and 34 actinomycetes were isolated: 21 Micromonospora strains, 10 Streptomyces, and 3 Pseudonocardia. Potentially, all 21 Micromonospora strains are novel, as revealed by an original identification scheme developed to assess quickly and easily the novelty of newly isolated environmental Micromonospora strains. Standardized media for testing physiological characters of Micromonospora were developed, and additional physiological characteristics of 15 of the validly published members of Micromonospora are described. Micromonospora isolates grew under anaerobic conditions. 8 new Micromonospora species are proposed. The antibiotic biosynthetic capability of strains was assessed by PCR targeted amplification of antibiotic biosynthetic and resistance genes (oxyB, ARO-PKS, ANSA, grm, fmr). An aminoglycoside antibiotic susceptibility plate assay and the grm and fmr PCR primers revealed the presence of aminoglycoside resistance genes in the genome of Micromonospora and suggested that these strains are capable of synthesizing aminoglycoside-type antibiotics.