Antifungal Peptides from a Burkholderia Strain Suppress Basal Stem Rot Disease of Oil Palm

Abstract

Basal stem rot (BSR) is the most common disease of oil palm (Elaeis guineensis Jacq.) in Southeast Asia. BSR is caused by a white-rot fungus Ganoderma boninense. The disease is difficult to manage. Therefore, development of novel and environmentally safe approaches to control the disease is important. Species of Burkholderia are known to have diverse lifestyles, some of which can be beneficial to plants either by suppressing diseases or enhancing plant growth. In the present study, antifungal peptides (AFPs) produced by a bacterial strain isolated from the rhizosphere of an oil palm tree, namely Burkholderia sp. strain CP01, exhibited strong growth inhibition on G. boninense. A loss-of-function mutant of CP01 was generated, and it has enabled the identification of a 1.2 kDa peptide and its variants as the active antifungal compounds. High-resolution mass spectrometry revealed six analogous compounds with monoisotopic masses similar to the previously reported cyclic lipopeptides occidiofungin and burkholdine. The antifungal compounds of CP01 were secreted into media and we sought to use CP01 culture extract without living cells to control BSR disease. Glasshouse experiments showed that CP01 culture extract suppressed BSR disease in oil palm seedlings. The ability of CP01 to produce an antifungal substance and suppress plant disease suggests its potential application as a biofungicide in agriculture.

Comparison of the colonization ability of Burkholderia strain B23 in the citrus rhizoplane and rhizosphere and assessment of the underlying mechanisms using full‐length 16S rDNA amplicon and metatranscriptomic analyses

“…Occidiofungin and ornibactin have been demonstrated to be the key metabolites of several Burkholderia species for inhibiting the growth of fungal and bacterial competitors, respectively (Deng et al, 2017 ; Gu et al, 2011 ; Jia et al, 2022 ; Prihatna et al, 2022 ). Occidiofungin and ornibactin biosynthesis loci were identified in strain B23, with all the genes exhibiting a high degree of conservation with those in the well‐studied strain B. contaminans MS14 (Figures 3 and 4 ).…”

“…At 3 dpi, the expression levels of all these genes were higher than those at 1 dpi in both the rhizosphere and rhizoplane. In particular, ambR1 , the key positive regulator of occidiofungin synthesis, and several other occidiofungin synthesis‐related genes, including ocfD , ocfI , ocfK , and ocfM , were significantly upregulated in the rhizoplane, whereas all the genes in the locus were significantly upregulated in the rhizosphere ( p < 0.05) (Deng et al, 2017 ; Gu et al, 2011 ; Jia et al, 2022 ; Prihatna et al, 2022 ). Interestingly, compared with 3 dpi, the expression levels of all the analysed genes did not change dramatically at 9 dpi in the cells colonizing the rhizoplane; however, the expression levels were significantly downregulated in the cells colonizing the rhizosphere (Figures 2 and 3C ).…”

“…The gradients of these nutrients attract bacteria towards the rhizoplane from the rhizosphere; however, because of the selective pressures exerted by the plant host and rhizoplane microbes, only certain taxa can successfully colonize the rhizoplane (Knights et al, 2021 ;Reinhold‐Hurek et al, 2015 ; Zhang et al, 2021 ). Interestingly, the gene loci for synthesizing the two key secondary metabolites occidiofungin and ornibactin, which are the most important weapons for exerting antagonistic effects against fungi and bacteria, respectively (Deng et al, 2017 ; Gu et al, 2011 ; Jia et al, 2022 ; Prihatna et al, 2022 ), were induced during the rhizoplane colonization process; these genes maintained a relatively high expression level in the rhizoplane when strain B23 became relatively stable in the niche (Figures 2 , 3 , 4 ). Furthermore, several genes involved in resistance to plant‐derived ROS stress and microbial competition‐related antibiotics and toxins were upregulated in the rhizoplane compared with the rhizosphere during the colonization process of stain B23 (Figure 2 ).…”

Isolation and lipid production of thraustochytrids from fishing village in Tangkolak Indonesia

“…Culture extract of Paraburkholderia sp. CP01 containing antifungal compound were also added to the agar media to selectively inhibit yeast growth (Prihatna et al 2022). The samples were then observed under a microscope for possible thraustochytrids identi cation.…”

Tempeh flour as an excellent source of paraprobiotics

“…First, 100 µL of the bacterial suspension was serially diluted to 10 -4 . Then, the suspension was spread on Man-Rogosa Sharpe Agar (MRSA) media with the addition of 0.5% (w/v) calcium carbonate (CaCO3) (Merck, Darmstadt, Germany) and 5% (v/v) ProPlant C (an in-house peptidebased antifungal compound) (Prihatna et al 2022) to determine the LAB population. Next, Eosin Methylene Blue Agar (EMBA) media (Merck) was used to grow bacteria from the Enterobacteriaceae family.…”