Decolourization of congo red synthetic dyes by dark septate endophytes

The use of fungi is known to be an eco-friendly and cost-competitive approach to degrade synthetic dyes such as Congo Red (CR) in industrial effluents. This research aimed to evaluate the potential of dark septate endophytes (DSE) fungi in decolourizing CR synthetic dyes. Two DSE strains, namely CPP and KSP, were studied to decolourize 50 mgL−1 CR based on the capability to produce the ligninolytic enzyme, dye decolourization efficiency, decolourization index, and fungal dry biomass weight after 7 and 14 days of incubation. CR decolourization was monitored spectrophotometry at 495 nm. The result indicated that CPP and KSP were successfully decolourized CR dye up to 97.00% and 85.00%, respectively, with decolourization index of 1.37 and 1.36 within 14 days. There is no significant difference in DSE growth with and without the addition of CR dye. In addition, these two DSE fungi (CPP and KSP) are able to produce ligninolytic enzymes. The results indicated that the DSE are potential to be used as decolourization agents for azo synthetic dyes. This is the first report on the ability of DSE to decolourize azo synthetic dyes.

Antagonistic capacity of dark septate endophytes (DSE) against Ganoderma boninense from oil palm (Elaeis guinensis Jacq.)

Ganoderma boninense, a causal agent of basal stem rot, as one of the major problems in oil palm plantation in Indonesia. The potential of dark septate endophytes (DSE) as biocontrol agents for G. boninense is not widely studied. Therefore, this study aims to screen DSE strains to obtain high antagonistic strains. The antagonistic capacity of 10 DSE strains was determined based on the growth inhibition in the dual culture, and volatile compounds challenge against G. boninense, in vitro. Volatile compound profiling of selected DSE strains that showed the highest challenge capacity was done using Pyrolysis Gas Chromatography-Mass Spectrometry. Among 10 DSE strains tested, TKC 2.2a had the highest percentage of G. boninense inhibition in dual cultures and the volatile compound challenge. This strain inhibited better if grown in media seven days earlier than grown simultaneously with G. boninsense. The volatile compounds of 14 days old TKC 2.2a were of 2H-1-Benzopyran-7-ol, 3,4-dihydro-5-methoxy-6-methyl-2-phenyl; 4-Allyl-2,6-dimetho-xyphenol; and hexa-decanoic acid, which were reported as having either antimicrobial or antifungal activities. These results indicate that DSE TKC 2.2a can be a candidate for a biocontrol agent against G. boninense in oil palm, depending on further research on its ability to reduce basal stem rot symptoms.

Advances in the Role of Dark Septate Endophytes in the Plant Resistance to Abiotic and Biotic Stresses

Endophytic fungi have been studied in recent decades to understand how they interact with their hosts, the types of relationships they establish, and the potential effects of this interaction. Dark septate endophytes (DSE) are isolated from healthy plants and form melanised structures in the roots, including inter- and intracellular hyphae and microsclerotia, causing low host specificity and covering a wide geographic range. Many studies have revealed beneficial relationships between DSE and their hosts, such as enhanced plant growth, nutrient uptake, and resistance to biotic and abiotic stress. Furthermore, in recent decades, studies have revealed the ability of DSE to mitigate the negative effects of crop diseases, thereby highlighting DSE as potential biocontrol agents of plant diseases (BCAs). Given the importance of these fungi in nature, this article is a review of the role of DSE as BCAs. The findings of increasing numbers of studies on these fungi and their relationships with their plant hosts are also discussed to enable their use as a tool for the integrated management of crop diseases and pests.

Combined inoculation with dark septate endophytes and arbuscular mycorrhizal fungi: synergistic or competitive growth effects on maize?

Background Effects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species. Methods Suspensions of DSE isolated from Stipa krylovii were prepared at different densities (2, 4, and 8 × 105 CFU mL− 1) and inoculated separately (AMF or DSE) or together (AMF + DSE), to explore their effects on maize growth. Results Inoculation with AMF or medium and high densities of DSE and combined inoculation (AMF + DSE) increased plant above-ground growth and altered root morphology. Differences in plant growth were attributable to differences in DSE density, with negative DSE inoculation responsiveness at low density. AMF promoted plant above-ground growth more than DSE and the high density of DSE promoted root development more than AMF. Combined inoculation might lead to synergistic growth effects on maize at low density of DSE and competitive effects at medium and high DSE densities. Conclusions AMF and DSE co-colonized maize roots and they had positive effects on the host plants depending on DSE density. These findings indicate the optimum maize growth-promoting combination of AMF and DSE density and provide a foundation for further exploration of potentially synergistic mechanisms between AMF and DSE in physiological and ecological effects on host plants.