Microscale microbial culture.

Abstract

The culture of microorganisms dates back to the early times of human civilization. Yeast and bacteria were used as mixed cultures for the preparation of food such as cheese, beer, bread, pickling of meat, and for fabric production, farming and nutrition. The invention of the microscope in the 1600s led to the accurate description of microorganisms, and later to the definition of pure and defined cultures containing single species versus a pastiche of mixed and, often unknown, concoction of many organisms. The growth and maintenance of pure cultures isolated from contaminating environmental microbes was achieved by ingenious culture techniques devised in the late 1800s: the swan-necked Pasteur flask, the conical Erlenmeyer flasks, Petri dishes with overhanging lids and the usage of solid agar in glass plates pioneered by Koch and coworkers. Remarkably, these ‘traditional’ culture techniques have changed very little since then, and are still widely used in almost all microbiology labs even today. As a discipline, while microbiology has revolutionized science by spurring major discoveries in molecular biology, genomics and proteomics, microbial cell culture has resolutely lagged behind the other fields for the longest time. It may be fair to comment that, at least until recently, the technological improvements in automation, novel devices, computational and analytical techniques have not had a serious impact in the practice of microbial cell culture per se. It was almost 100 years after the invention of the Petri dish that a significant advancement was made with the introduction of multiwell plates in the late 20th century. The well plates increased the culture densities by 10- to 100- fold compared with that of flasks or dishes. In the past 10 years, there has been radical shift in the craft of microbial culture with the introduction ‘microscale cell cultures’. The microscale cultures are highly miniaturized with three to six orders of magnitude increase in cell density and throughput compared with traditional culture methods [1]. The microscale cell cultures have not only given us glimpses into the microbial wonderland but also have spawned technological innovations for many practical applications. In this article, we present a survey of the current status of microscale microbial culture, and speculate what the immediate future may hold.