Table 2.

Some novel bioactives and biosynthetic pathways of industrial interest discovered through functional metagenomics.

Bioactive /Pathway	Closest known homolog	Method/Host	Environment	References
Pederin	>80% identity to sequences from P. aeruginosa. The discovered ped gene cluster is believed to be from a symbiont of the Paederus beetle from the genus Pseudomonas	Targeted sequencing-based strategy	Paederus beetles	Piel, 2002
Biotin	Highest identity to proteins from Erwinia herbicola. Significant identity also shown to proteins from E. coli and Pseudomonas putida	Selelction-based screening of enriched cosmid library in E. coli biotin auxotrophic strain	Horse excrement	Entcheva et al., 2001
Known siderophore: vibrioferrin	98% identity to proteins from Vibrio parahaemolyticus and Vibrio alginolyticus	Function-based screening of E. coli plasmid library	Tidal-flat sediment, Ariake Sea	Fujita et al., 2011
Polyketide synthase (PKS) gene	55–59% identity to hypothetical PKS from Mycobacterium avium (NP_961164)	Targeted sequencing-based strategy	Marine sponge Discodermia dissoluta, Netherlands Antilles	Schirmer et al., 2005
Novel serine protease inhibitor (serpin) gene	Moderate identities to serpins from Salinibacter ruber M8 and Spirosoma linguale DSM 74. Similarities with possible partial serpins from Dyadobacter fermentans DSM 18053, Arthrospira maxima CS-328 and Cyanothece sp. PCC 7822	Sequence-based screening of E. coli plasmid library.	Uncultured marine organisms	Jiang et al., 2011
Borregomycin A and B encoded by bor pathway (antiproliferative and antibiotic properties)	ORFs showing 32–86% identity to species from the following genera: Micromonospora, Streptomyces, Actinoplanes, Corallococcus, Cellulomonas, Actinomadura, Salinispora, Microlunatus, Modestobacter, Frankia, Saccharomonospora, Nocardia, Phaeosphaeria	Homology guided screening	Soil, Anza-Borrego Desert (CA)	Chang and Brady, 2013
Hypothetical protein with NF-kB pathway stimulatory activity	42% of predicted genes coverage to B. vulgatus ATCC 8482	Activity-based screening using a reporter cell line of an E. coli fosmid library	Human gut microbiota of Crohn's Disease patients	Lakhdari et al., 2010
Novel prebiotic degradation pathways (11 contigs)	Sequence homology to species of Bifidobacterium, Eubacterium, Streptococcus, Bacteroides, Faecalibacterium	Hydrolytic activity-based selective screening of two E. coli fosmid libraries	Human ileum mucosa and fecal microbiota samples	Cecchini et al., 2013
Five novel putative salt tolerance genes	Identity to hypothetical proteins from genus Collinsella, Eggerthella, and Akkermansia	Function-based screening of E. coli plasmid library	Human gut microbiota	Culligan et al., 2012
Novel salt tolerance gene	Not homologous to any sequence at time of study, highest BLAST score to hypothetical protein from Caulobacter crescentus	Function-based screening of E. coli plasmid library	Faecal sample, healthy 26 year old Caucasian male	Culligan et al., 2013
15 acid resistance genes	37–90% identity to proteins and hypothetical proteins from the following genera: Thermosinus, Streptomyces, Candidatus, Hyphomicrobium, Methylococcus, Acidithiobacillus, Thioalkalivibrio, Nitrosococcus, Halorhodospira, Haliangium, Clostridium, Roseomonas, Acidiphilium, Gemmata, Terriglobus, Burkholderia	Function-based screening of six E. coli plasmid libraries. Followed by expression in Pseudomonas putida and Bacillus subtilis	Planktonic and rhizosphere microbial communities of the Tinto River. Five libraries from Erica andevalensis, one from headwaters of Tinto River	Guazzaroni et al., 2013