Diversity and antimicrobial activity of endophytic fungi isolated from Securinega suffruticosa in the Yellow River Delta

Abstract

Securinega suffruticosa (Pall.) Rehd is an excellent natural secondary shrub in the Shell Islands of Yellow River Delta. The roots of S. suffruticosa have high medicinal value and are used to treat diseases, such as neurasthenia and infant malnutrition. Any organism that is isolated from this species is of immense interest due to its potential novel bioactive compounds. In this research, the distribution and diversity of culturable endophytic fungi in S. suffruticosa were studied, and the endophytic fungi with antimicrobial activity were screened. A total of 420 endophytic fungi isolates were obtained from the S. suffruticosa grown in Shell Islands, from which 20 genera and 35 species were identified through morphological and internal transcribed spacer (ITS) sequence analyses. Chaetomium, Fusarium, Cladosporium, and Ceratobasidium were the dominant genera. The high species richness S (42), Margalef index D 0 (5.6289), Shannon-Wiener index H 0 (3.1000), Simpson diversity index D s (0.9459), PIE index (0.8670), and evenness Pielou index J (0.8719) and a low dominant index λ (0.0541) indicated the high diversity of endophytic fungi in S. suffruticosa, the various species of endophytic fungi with obvious tissue specificity. The inhibition percentages of the 12 species of such endophytic fungi against Colletotrichum siamense were 3.6%-26.3%. C. globosum, Fusarium sp.3, and C. ramotenellum had a high antibacterial activity against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were between 0.5 mg/mL and 2 mg/mL. Alkaloid content detection indicated that endophytic fungi had a high alkaloid content, whereas the alkaloid contents of C. globosum and Fusarium sp.3 reached 0.231% and 0.170%, respectively. Members belonging to the endophytic fungal community in the S. suffruticosa of Shell Islands that may be used as antagonists and antibacterial agents for future biotechnology applications were identified for the first time.

Evaluation of the stability and antibacterial activity of crude extracts of hydro-endophytic fungi

“…Fungal crude extracts with antibacterial activity were further examined for their MIC and MBC by the agar disc-diffusion assay[ 20 ] against MRSA [ Table 5 ]. EtOAc and MeOH extracts of EF14 had MIC value of 4.80 and 4.90 mg/mL, respectively, though only EtOAc extracts displayed MBC at the concentration of 9.60 mg/mL.…”

Bacterial Endophyte Community Dynamics in Apple (Malus domestica Borkh.) Germplasm and Their Evaluation for Scab Management Strategies

“…The wilt prevalence in eggplant to an extent of more than 70% was reported to be contained by the formulations of Pseudomonas sp., Enterobacter sp., and Bacillus sp., and it was found that most of these isolates produced an antibiotic DAPG under in vitro conditions [75]. The naturally-occurring bacterial endophytes that could confer a prominent disease resistance to plants are very low in number and such populations have to be raised to a specific level in order to encourage a contrasting check in the proliferation of phytopathogens [76].…”

Effect of Charcoal on the Properties, Enzyme Activities and Microbial Diversity of Temperate Pine Forest Soils

“…The relative frequency (RF) was expressed as the ratio of the number of isolates of a specific taxon to the total number of isolates in each nest. Dominance (Y) was calculated as described by Du et al [50]; a dominant genus was defined when Y > 0.02. The following ecological diversity measures used by Du et al [50] and characterised by Magurran [51] were calculated for each nest: species richness index (S), Margalef index (D ), Shannon-Wiener index (H ), Simpson diversity index (D s ), Simpson dominant index (λ), Pie index (PIE) and Pielou's evenness index (J).…”