Fig 1.
Electronic, micro-hydraulic and filters components.
A) System components such as the pump, microcontroller, solenoid valve, flow sensor, manifold, pressure gauge, filters and filters cartridge used in the development of the IS-ABS. B) Sterivex-GP filter image (left) and Sterivex-GP filter diagram and water flow (right) during filtration procedure (adapted from User Guide [15]).
Fig 2.
Main electronic blocks developed and how they connect to each other.
Fig 3.
Water and RNAlater circuit with the solenoid valves that control which circuit is being used and the relative location of the pump and sensors.
Fig 4.
Embedded microcontroller software structure.
Representation of the five tasks that are running in the microcontroller and which sensor or actuator is being connected to it. The information between them passed though a set of message queues and global event bits.
Fig 5.
Embedded control software state machine.
State machine implemented in the microcontroller firmware for global control of the system. The flags START COMPLETE and ABORT are set with information from the tasks that are processing the sensors signal.
Fig 6.
High level control and configuration.
The user interface is based on a web page where the mission is configured and then saved on a local database (SSD disk). The mission in then passed to the embedded electronics through a RS-232 protocol.
Fig 7.
The filtration of the different replicates started simultaneously in the OSD procedure and in the IS-ABS in the different carboys.
Fig 8.
Field autonomous biosampler prototype components (left) and CAD model (right). The components are all mounted inside a cylinder in vacuum.
Fig 9.
In situ autonomous biosampler (IS-ABS) prototype.
Water inlet/outlet (A); external connector interface (B); opened in the field (C); integrated in a multi-sensor system.
Fig 10.
Design of the filter cartridge box open (A) and closed (B); and Sterivex filter cartridge image (C).
Table 1.
Filtration time, volume, average flow and environmental DNA recovered.
In the tests performed with the Ocean Sampling Day (OSD) standard procedure and the autonomous biosampler (IS-ABS) (mean ± standard deviation, n = 3). For IS-ABS, two filtration pressures were selected. Different superscript letters indicate significant (ANOVA, P < 0.05) differences among the three filtration procedures for each parameter.
Table 2.
Diversity indices for 16S and 18S rDNA.
Calculated in the samples recovered using either the Ocean Sampling Day filtration standard procedure and the autonomous biosampler (IS-ABS) (mean ± standard deviation, n = 3). For IS-ABS two filtration pressures (1 and 1.3 bars) were used. Different superscript letters indicate significant (ANOVA, P < 0.05) differences among the three filtration procedures for each diversity index.
Table 3.
Relative percentage (>1%) of 16S OTUs (Bacteria and Archaea) taxonomic composition at phylum level.
Detected in the tests performed with the Ocean Sampling Day (OSD) standard procedure and with the autonomous biosampler (IS-ABS) (mean ± standard deviation, n = 3). For IS-ABS two filtration pressures were selected (1 and 1.3 bar). Different superscript letters indicate significant (ANOVA, P < 0.05) differences among the three filtration procedures for each phylum.
Table 4.
Relative percentage of 18S OTUs Taxonomic composition at phylum level.
Detected in the tests performed with the Ocean Sampling Day (OSD) standard procedure and with the autonomous Biosampler (IS-ABS) (mean ± standard deviation, n = 3). For IS-ABS two filtration pressures were selected (1 and 1.3 bars). Different superscript letters indicate significant (ANOVA, P < 0.05) differences among the three filtration procedures for each phylum.
Fig 11.
Distribution of the abundant taxa (>1%) retrieved from the 16S rDNA (A) and 18S rDNA (B) OTUs taxonomic composition at lower taxonomic level. Detected in the testes performed with the Ocean Sampling Day (OSD) standard procedure and with the autonomous biosampler (IS-ABS) (mean ± standard deviation, n = 3). For IS-ABS two filtration pressures were selected (1 and 1.3 bar). No significant differences (ANOVA, P ≥ 0.05) were observed among the three filtration procedures for the relative percentage of each genus.