Diversity and community structure of endophytic Bacillus with antagonistic and antioxidant activity in the fruits of Xisha Wild Noni (Morinda citrifolia L.). (September 2021)

• Record Type: Journal Article
• Authors: Sun, Biqi; Jing, Ruixue; Wang, Zhishan; Tian, Liang; Mao, Feifei; Liu, Yang
• Is Part Of: Microbial pathogenesis. Volume 158(2021)
• Publication Date: 2021-09
• Subjects: Noni -- Endophytic bacteria -- Identification -- Bacillus -- Antagonistic activity -- Antioxidant activity; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2021.105065
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: Noni ( Morinda citrifolia L.) is a tropical crop with strong antibacterial, antioxidant and other abilities, and its fruit has a strong potential for adjuvant treatment of diseases. This study aimed to explore the dynamic change of endophytic bacteria in Noni fruit at different stages and the correlation between the antagonistic and antioxidant activity of the Bacillus which was screened and the change of the host's growth stage. In this study, though the high-throughput sequencing technology (HTS), 106 endophytic bacteria species were found in A, B, C, D, E and F stages of Noni fruit, among which the dominant group were Pantoea (0.3%–20.9%), and Candidatus _Uzinura (2.3%–35.2%) etc. The endophytic bacteria were isolated by culture-dependent method. Through their antagonistic experiments on Staphylococcus aureus and Escherichia coli, the results of 16S polyphasic taxonomic identification showed that the 34 antagonistic strains belonged to Bacillus . Five species of these Bacillus were identified by gyrA polyphase taxonomy, including Bacillus subtilis (76% of all Bacillus ), Bacillus licheniformis (9%), Bacillus amyloliquefaciens (6%), Bacillus velezensis (6%) and Bacillus mojavensi (3%), and the RAPD showed these Bacillus are no signs of stable passage. In C, D, E and F stages, the average total antioxidant activity of Bacillus endophytic antagonists against Noni was 7.812 U/mL, 8.144 U/mL, 7.817 U/mL and 7.144 U/mL, which was much higher than that of Noni fruit, and antioxidant activity of Noni juice and Bacillus bacterial liquid vary with host's growth period showed the same trend, both rose slowly at first, and reached the highest in period E, then declined slightly in period F, it showed that the antagonistic Bacillus of Noni had synergistic function with Noni fruit. This study clarified the relationship of function between Noni fruit and endophytic bacteria, and laid a foundation for future study on the dynamic change of endophytic flora succession and efficacy. Highlights: 1) Probing the microbial diversity of Noni fruit at different stages using high-throughput sequencing technology. 2) Through the dural culture method and 16s polyphasic taxonomic identification, some Bacillus strains are significantly antagonistic abilities against E. coli and Staphylococcus aureus. 3) These strains were identified as Bacillus subtilis, Bacillus licheniformis, Bacillus amyloliquefaciens, Bacillus velezensis and Bacillus mojavensi. 4) The total antioxidant activity in Noni fruit and in endophytic Bacillus in the corresponding periods was tested and showed the same trend, with a slight increase at first, and reached the highest in period E and a slight decrease in period F.