Here we have a collection of some ways to use PREGO knowledge base and how to visualise the resulted networks using tools like Arena3D web.
There are cases that microbiologists are focused on specific environmental characteristics in their research. An important abiotic characteristic of environments is salinity. As climate change accelarates, salinity in various habitats is also increased and an important challenge is the advancements of agriculture crops with microbiome symbiotes tolerant in high salinity.
PREGO, being a data and metadata aggregator, can provide microbes and their processes that are associated with Environmental Ontology terms of saline environments. These are:
ENVO:00000017 saline hydrographic feature
ENVO:00000019 saline lake
ENVO:00000054 saline marsh
ENVO:00000055 saline evaporation pond
ENVO:00000226 saline wedge estuary
ENVO:00000240 saline wetland
ENVO:00000279 saline pan
ENVO:00002010 saline water
ENVO:00002012 hypersaline water
ENVO:00002121 alkaline salt lake
ENVO:00002197 saline water aquarium
ENVO:00002209 saline lake sediment
ENVO:00005775 salt contaminated soil
ENVO:01000022 marine salt marsh biome
ENVO:01000307 saline water environment
ENVO:00002252 solonchak
ENVO:00002255 solonetz
ENVO:00000369 brine pool
ENVO:00003044 brine
Searching the PREGO knowledge base for the above terms results in multilayer network data, environments, microbes and processes as compliled from the Literature, Environmental Samples and Annotated Genomes.
PREGO's knowledge space contains 94042 associations of these entities from all channels combined. This information is obtained by a filtering script executed on bulk data available for download (see the paper)
20344 experiments
94 knowledge
73604 textmining
PREGO scoring scheme assists in filtering the most probable associations. In this case we filtered the Literature channel associations with score higher that 4.8 and the rest of the channels with score higher or equal to 3.
gawk -F"\t" '{if ($1 ~ /textmining/){if ($6>4.8){print $0}} else {if ($8>=3){print $0}}}' saline_envo_pairs.tsv > saline_envo_pairs_filters.tsv
Narrows down to these associations
491 experiments
94 knowledge
711 textmining
In order to add metadata we create a file that contains the ids, name, layer and rank (if it is a taxon). We further filter the microbes to keep only species and strains taxonomic levels.
gawk -F"\t" '(ARGIND==1){terms[$3]=1; terms[$5]=1}(ARGIND==2){rank[$1]=$5}(ARGIND==3 && ($2 in terms)){if ($1==-2) {if (rank[$2]=="species" || rank[$2]=="strain"){print $2 FS $3 FS $1 FS rank[$2]}} ; if ($1 !="-2" && $1 !=-3) {print $2 FS $3 FS $1 FS "na"} }' saline_envo_pairs_filters.tsv nodes.dmp /data/dictionary/database_preferred.tsv > saline_envo_pairs_metadata.tsv
Because of the last filtering of species and strains we have to filter the edgelist again based on the latest ids.
gawk -F"\t" 'FNR==NR{terms[$1]=1; next}($5 in terms){print}' saline_envo_pairs_metadata.tsv saline_envo_pairs_filters.tsv > saline_envo_pairs_edgelist.tsv
To display all the attributes names instead of ids run the following line
gawk -F"\t" 'BEGIN{channel["-2"]="Organism";channel["-27"]="Environment";channel["-21"]="Biological Process";channel["-23"]="Molecular Function"}(ARGIND==1){node[$1]=$2}(ARGIND==2){ if (FNR==1) {print $0} else {print node[$1] FS node[$2] FS $3 FS channel[$4] FS channel[$5] FS $6}}' prego_saline_environments/saline_envo_pairs_metadata.tsv prego_saline_environments/saline_envo_pairs_edgelist-arena.tsv > arena_example_prego_saline_edgelist_names.tsv
The final network has 4 layers, 758 nodes and 904 edges in total.
- Microorganisms in Saline Environments: Strategies and Functions
- Environmental Microbiology: Fundamentals and Applications
PREGO users can query with a single term to find the associated terms. For example, anaerobic ammonium oxidation. This redirects the user to organisms that this process is found in the Literature channel. Then the user can select organisms that are of interest, for example Beggiatoa. This genus is known since the 19th century for oxidizing hydrogen sulfide. These microorganisms are found in both marine and fresh water in various habitats such as sendiment, mangooves, etc.
Some information regarding the relation of anaerobic ammonium oxidation and Beggiatoa that Literature channel unearthed:
Previous studies have observed that both denitrification and anammox in anoxic sediments can be supported by intracellular nitrate transport performed by sulfide-oxidizing bacteria like Thioploca and Beggiatoa (Mußmann et al., 2007; Jørgensen, 2010; Prokopenko et al., 2013) down to deeper sediment layers and possibly supplying anammox bacteria with nitrite and/or ammonia produced by DNRA (source - PMID: 27812355)
So Beggiatoa assist neighbor microbes with annamox in anoxic sediments.
Furthermore, users can select microorganisms to further expand the indirect associations of annamox with the environments. For example using Beggiatoa to find the associated environment types we selected the top 12 environments from the Literature channel and the top 8 environments from the Environmental Samples channel to a total of 20 environment associations. This compilation forms a tripartite network with Biological Processes, Organisms and Environments as layers. There are two types edges that show the PREGO channel that each is association is derived from forming a multi-edged network. This network can be visualized with Arena3D web. There are 2 associations of Beggiatoa with Environments, sediment and coast, that form multi-edges.