• Microfluidic technology promotes the development of soil bacteria research. • Microfluidics can achieve real time observation and analysis of microorganisms in controlled environments. • Microfluidics generally use optical and electrochemical methods to detect single cells combined with polymerase chain reaction (PCR) to realize high throughput gene detection on chips. • Microfluidics is mainly applied in chemotaxis, biofilm, antibiotic and horizontal gene transfer research of soil bacteria.
Soil science is an inherently diverse and multidisciplinary subject that cannot develop further without the continuous introduction and promotion of emerging technologies. One such technology that is widely used in biomedicine and similar research fields, microfluidics, poses significant benefits for soil research; however, this technology is still underutilized in the field. Microfluidics offers unparalleled opportunities in soil bacterial cultivation, observation, and manipulation when compared to conventional approaches to these tasks. This review focuses on the use of microfluidics for bacteria research and, where possible, pulls from examples in the literature where the technologies were used for soil related research. The review also provides commentary on the use of microfluidics for soil bacteria research and discusses the key challenges researchers face when implementing this technology. We believe that microfluidic chips and their associated auxiliary technologies provide a prime inroad into the future of soil science research.
• Soil nematode samples can be quite turbid, which are not satisfactory for microscopy. • Three methods were designed for cleaning turbid nematode suspensions. • Nematode abundance did not significantly differ among control and the three methods. • Repeated centrifugation had slightly higher recovery rate of nematodes than the other methods.
Soil nematodes are useful ecological indicators and can be extracted from soil by a variety of techniques. Because the extracted nematode samples (suspensions) can be quite turbid (i.e., they contain soil particles and organic particles in addition to nematodes), quantitative and taxonomic analyses of the nematodes by microscopy can be difficult. In this study, the following three methods for cleaning turbid suspensions obtained from Baermann funnels were assessed: repeated centrifugation at 692.5´g for 1 min, repeated settling at low-temperature (4°C) for 24 h, and a combination of low-temperature settling and centrifugation. Nematodes were extracted with Baermann funnels from soil samples collected from four land-use types (since land-use type can affect the turbidity of nematode suspensions), and the resulting suspensions were cleaned by the three methods before nematode abundance was assessed. As a control, samples (i.e., suspensions) were simply diluted with water, and nematodes were counted in the entire volume. The results showed that, within each land-use type, nematode abundance did not significantly differ between the control and the three cleaning methods. Averaged across all land-use types, however, the nematode recovery rate was slightly higher with repeated centrifugation than with the other two cleaning methods. Therefore, the proposed methods are sound for cleaning turbid nematode suspensions, and repeated centrifugation is the most efficient method.
