Serratia fonticola: Emerging Versatile Player in Environmental and Biotechnological Applications

Overview of the Microbe#

Serratia fonticola is a Gram‑negative, rod‑shaped bacterium in the family Enterobacteriaceae, first described from freshwater habitats and now recognized in soils, wastewater, and plant rhizospheres[1]. It grows aerobically or anaerobically, ferments a range of sugars and alcohols, and tolerates diverse pH and salinity conditions. The type strain LMG 7882^T genome (~5.6 Mbp) reveals metabolic pathways for carbohydrate catabolism, siderophore production, and stress response, supported by multiple 16S rRNA gene copies for robust ecological adaptation.

Bioremediation of Hydrocarbons and Heavy Metals#

Hydrocarbon Degradation#

In anaerobic co‑digestion of refinery oily sludge, S. fonticola has been identified as a dominant hydrocarbon‑degrading bacterium, contributing to ≥ 92 % removal of organic content and enhanced methane yields[6]. Its presence in poultry manure–sludge mixes correlates with accelerated breakdown of complex petroleum fractions, underscoring its potential in waste‑to‑energy bioprocesses[6].

Heavy Metal Remediation#

Endophytic strain CPSE11 exhibits strong resistance to cadmium, lead, and arsenic, sequestering metals via EPS‑mediated sorption and metallophore chelation, and promoting plant growth in contaminated soils[7]. Two Ga/In‑resistant isolates demonstrated inducible oxidative‑stress defenses and metal efflux systems, maintaining viability under high metal loads, which could be harnessed for bioremediation of metalliferous effluents[8].

Plant Growth Promotion and Biocontrol#

Genome sequencing of DSM 4576^T confirmed genes for phosphate solubilization, indole‑3‑acetic acid (IAA) synthesis via the GS/GOGAT and IAM pathways, hydrogen cyanide production, and siderophore biosynthesis, all hallmark PGPR traits[3]. Quorum‑sensing‑deficient mutants of GS2 lose IAA and ACC deaminase activity and form weaker biofilms, verifying AHL‑mediated regulation of PGP functions[4]. Co‑inoculation of S. fonticola S1T1 with Pseudomonas koreensis S4T10 synergistically improved cucumber seedling biomass under salinity stress (200 mM NaCl), demonstrating its utility in ameliorating abiotic stresses in horticulture.

Industrial Enzyme Production#

S. fonticola strain GS2 exhibits high transcription of nitrile hydratase genes (nthA, nthB), enabling efficient conversion of nitriles to amides like acrylamide and nicotinamide under mild conditions; this aligns with industrial demands for greener amide synthesis[10][2]. Although protease and chitinase production is better characterized in Serratia marcescens, S. fonticola genomes encode esterases and dehydrogenases that may be exploited for specialty biocatalysis pending optimization[1].

Biosurfactant and Bioemulsifier Synthesis#

Members of the genus Serratia produce lipopeptide biosurfactants (serrawettins) and glycolipids (rubiwettins) that reduce surface tension and emulsify hydrophobic compounds[9]. Genomic analyses of several S. fonticola strains reveal serrawettin‑W2 gene clusters, indicating potential for in situ biosurfactant generation to enhance hydrocarbon bioavailability and microbial colonization in contaminated matrices .

Challenges and Future Potential#

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Although generally non‑pathogenic, S. fonticola has been implicated in rare human infections—including urosepsis and emphysematous pyelonephritis—often displaying intrinsic β‑lactam resistance, highlighting the need for careful strain selection and containment[5]. Horizontal gene transfer and antibiotic‑resistance genes call for genome‑based risk assessments before field applications. Future work will leverage CRISPR/Cas tools, biosafety kill‑switches, and synthetic‑biology pipelines to engineer strains with enhanced pollutant‑degrading and PGP traits—while minimizing ecological risks—and to scale bioprocesses in bioreactors and biofertilizer formulations.

Spotlight on Research: Bacillus subtilis FJ3 Biocontrol Study#

Brief Overview#

Jung et al. (2017) reported the complete genome (6.1 Mbp chromosome + 132 kbp + 94 kbp plasmids) of S. fonticola strain GS2, a sesame rhizosphere isolate with PGP and quorum‑sensing abilities[11].

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Key Insights#

GS2 harbors luxI/luxR homologs for AHL synthesis, produces N‑hexanoyl‑HSL and N‑octanoyl‑HSL, and synthesizes IAA at 6.7 µg mL⁻¹—demonstrating genomic and phenotypic bases for root colonization and plant‑growth enhancement[11].

Why This Matters#

Understanding GS2’s signaling circuits and PGP pathways enables rational design of bioinoculants and the deployment of S. fonticola in sustainable agriculture, reducing fertilizer inputs and improving crop resilience.

Summary Table: Spotlight Study#

Category	Details
Lead Researchers	Byung Kwon Jung et al.
Affiliations	Kyungpook Natl. Univ.; AtoGen Co. Ltd.; UC San Francisco
Research Focus	GS2 genome and PGP‑QS traits
Key Breakthroughs	Genome assembly; luxI/R and IAA clusters; AHL & IAA confirmed[11]
Collaborative Efforts	Kyungpook Univ.–AtoGen–UCSF
Published Work	J. Biotechnol. 241:158–162
Publication Date	2017
Location	Korea & USA
Key Findings	GS2 produces C6‑ and C8‑HSL, 27.1 µg/mL indolic compounds, supports PGP[11]

Conclusion#

Serratia fonticola emerges as a multifaceted microbe bridging environmental cleanup, crop enhancement, and industrial biocatalysis. Its genomic toolkit for hydrocarbon and metal remediation, quorum‑sensing‑regulated PGP traits, nitrile biotransformation, and biosurfactant production positions it for diverse “green microbe” applications. Strategic strain engineering, biosafety profiling, and process optimization will be key to safely unlocking its full potential for sustainable biotechnology.

References#

1. Serratia fonticola – an overview. ScienceDirect Topics. ScienceDirect
   
2. Lavigne R et al. Nitrile hydratase and its industrial applications. Front Bioeng Biotechnol. 2020;8:352. Frontiers
   
3. Kim D et al. Complete Genome Sequence of Serratia fonticola DSM 4576^T. Int J Syst Evol Microbiol. 2015;65(Pt 11):3761–3766. PubMed
   
4. Park CE, Jung BK, Khan AR et al. Quorum Sensing System Affects the Plant Growth Promotion Traits of Serratia fonticola GS2. Front Microbiol. 2020;11:536865. Frontiers
   
5. Villasuso-Alcocer V et al. Serratia fonticola and its role as a single pathogen causing emphysematous pyelonephritis in a non‑diabetic patient: a case report. World J Clin Cases. 2022;10(29):10600–10605. ScienceDirect