Cultivation of recalcitrant microbes: cells are alive, well and revealing their secrets in the 21st century laboratory.

Any talk of the demise of in vitro cultivation as a useful mechanism for revealing many of nature's past and present secrets appears to be unfounded and premature. The first years of this century have been as productive in the cultivation of physiologically novel, environmentally abundant and phylogenetically distinct microbes as were the first years of the 20th century. The diversity of organic and inorganic electron donors and acceptors known to be used during microbial energy metabolisms continues to grow, expanding our appreciation for the niches that may be, or historically may have been, filled by microbes in the biosphere. Either guided and instigated by, or independent of, the results of gene inventories representing diverse environmental settings, significant advances are constantly being made in the isolation of bacteria and archaea, demonstrating either strikingly rich phylogenetic diversity or significant activity and abundance in their respective environments. The potential synergisms between molecular ecological analyses and innovative in vitro growth studies are real and should be embraced, rather than treated as dueling agents in some zero-sum game.