Pseudomonas fulva HARBPS9.1: candidate anti-Fusarium agent in South Africa

Abstract

Phytopathogens causing mycotoxicoses in maize are a potential threat to grain quality and availability in many maize producing countries including South Africa. The use of natural biological agents for controlling maize fusariosis and many other such plant diseases, as opposed to the more traditional use of chemicals, is growing in popularity globally, as a greater emphasis gets placed on public health. In this study, nine Fusarium inhibiting isolates representing a subset of 200 native Pseudomonas isolates from the maize rhizosphere of 10 different farms in the North West Province of South Africa were further evaluated for their in vitro biocontrol potential. Although few of the isolates (PS1.1, PS1.22, PS2.2, PS6.4, PS6.8, PS7.2, PS8.3, PS8.6, and PS9.1) had impressive in vitro biosuppressive effects against Fusarium graminearum and Fusarium culmorum, while also producing biosurfactants, only isolate HARBPS9.1 showed consistent antifungal capacity along with maize seed bioprotection capability. The candidate antagonist HARBPS9.1 was molecularly characterized as a Pseudomonas fulva strain and was found to harbor multiple functional biosynthetic gene clusters after FTIR, NMR and ESI-Q-TOF-MS metabolomics investigation. P. fulva HARBPS9.1 bioprotective mechanism is attributed to the possible presence of hydrogen cyanide, pyrrolnitrin, and rhamnolipids.

Draft Genome Sequences of Various Bacterial Phyla Isolated from the International Space Station

“…Three species from the phylum Proteobacteria were identified. Acinetobacter pittii is a less common nosocomial pathogen that causes pneumonia and meningitis in intensive care patients ( 16 ), Pseudomonas fulva is a commensal plant endophyte ( 17 ) that can also infect immunocompromised patients ( 18 , 19 ), and Pseudomonas granadensis is a recently discovered soil bacterium ( 20 ).…”

Evaluation of Pseudomonas fulva PS9.1 and Bacillus velezensis NWUMFkBS10.5 as Candidate Plant Growth Promoters during Maize-Fusarium Interaction

“…The consortia, however, enhanced plant growth and suppressed Fg activity better where Fg infection was included in the treatments. Whilst antagonist PS9.1 possesses some plant-growth-promoting and biocontrol compounds, rhamnolipids, pyoverdine, and rhizomide [ 22 , 32 ], the antagonist NWUMFkBS10.5 performed significantly ( p = 0.05) better than PS9.1 in all the treatments. This could be attributed to the action of its multiple plant-growth-promoting and biocontrol biosynthetic compounds, macrolactin, bacillibactin, mersacidin, bacilysin, surfactin, difficidin, iturin, and fengycin [ 21 , 33 ].…”

“…In previous reports, both the cells and crude extracts of Bacillus velezensis NWUMFkBS10.5 (Gram-positive) [ 21 ], and Pseudomonas fulva HARBPS9.1 (Gram-negative) [ 22 ], exerted biosuppressive activity against Fg . Here we assess the influence of these candidate biocontrollers on maize plants grown in the presence of the Fg pathogen during the maize pot experiment.…”

How Maize Seed Systems Can Contribute to the Control of Mycotoxigenic Fungal Infection: A Perspective

“…Work on strains of the fungus Trichoderma harzianum has shown promise both in the lab [33,34,36,75] and in the field [33,35]. Moreover, strains of bacteria from the genera Pseudomonas and Lactobacillus have been found to reduce contamination either in the field (contamination of Fusarium [37]; contamination of Aspergillus [76]) or post harvest (contamination of Aspergillus [77]). Much more field work under soil and disease pressure conditions typical to smallholder farmers in low-and middle-income countries will be needed, and input value chains will need to be developed.…”

“…Such strategies could involve biopriming of the seeds with Trichoderma harzianum Rifai [33][34][35], T. gamsii Samuels & Druzhin. [36], or Pseudomonas fulva Iizuka & Komagata [37].…”