Endophytes

Endophytes belong to the endosymbiotic category of bacteria that colonise microbes and plants, which can be distinguished easily in the plant growth media. They serve as repositories for novel bioactive secondary metabolites such as phenolic acids, alkaloids, quinones, saponins, tannins, steroids  and terpenoids, which have antibacterial anti-insect anticancer, and other activities. Chemical compounds for therapeutic reasons are being extensively researched; endophytic microorganisms are also a significant source for drug discovery. In this article, we will look into the meaning of endophytes with some examples to understand them more clearly and the types of endophytes. 

What are endophytes? 

Numerous surveys have been conducted, which focused on the pathogenicity relationships of microbes and plants with endophytes. However, following multiple research papers and recognized works by the significance of microbial variety about many types of plants, it has always been assumed that only some part, merely a fraction of microorganisms that interact, are pathogens. Most microorganisms that live in plants play an essential role in the plant’s development and health. However, some are neutral.

Apart from disease-causing bacteria, De Bary (1866) was the one who discovered the first occurrence of non-pathogenic material in the plant when he discovered microbial cells in microscopically studied plant tissues. This observation, however, remained unexamined, and hence the definition kept evolving and was finally developed in the last century.

Endophytes and bioactive compounds 

Endophytes have been demonstrated to produce a wide range of bioactive metabolites in a single plant or microbe, making them an attractive source of medicines for treating a wide range of ailments and with potential uses in agriculture, medicine, food, and cosmetics. Secondary metabolites were categorized into functional groups such as alkaloids, benzopyrones, steroids, phenolic acids, saponins, tannins, terpenoids, tetralones, xanthones, chinones, flavonoids, quinones, and many more. Several factors impact metabolite extraction from endophytes, such as sample collection season, environmental factors, and geographical location.

However, because of a modern synthetic approach, harvesting from plants and natural sources is now more feasible, efficient, and accessible. Endophytes’ bioactive substance production has been connected to the development of host microorganisms, which may have integrated genetic information from advanced plant species, enabling them to adapt better to the host plant and undertake some functions, such as protection from pathogens insects, and grazing animals.

Some of the more common Endophytes instances are as follows: Camptothecin, produced from Nothapodytes foetida, has antifungal and cytotoxic properties. Huperzine-A (HupA) is a cholinesterase inhibitor produced from the plant Huperzia Serrata. Anticancer compounds include cathartics, emetics, and cholagogues identified from endophytic Podophyllum hexandrum. Taxol (paclitaxol), a complex diterpene alkaloid produced by the endophyte Metarhizium anisopliae found in the bark of the Taxus tree, is one of the most promising anticancer medications available today. 

Association of  endophytes

Endophytes are associated with plants in various forms, including bacteria (actinomycetes or mycoplasma) or fungi that have been colonised inside the plant tissues. Sixteen Phyllis and two hundred genera of species of bacteria have been documented to be connected with endophytes, with the majority class belonging to the phylum Actinobacteria, Firmicutes and Proteobacteria. 

Actinomycetes

Actinomycetes belong to the class of prokaryotic microorganisms, a category of Actinobacteria phylum and have mycelium-like fungi, and produce spores. Historically, actinomycetes were thought to be intermediate forms between fungus and bacteria. However, the similarity that actinomycetes show with fungi is superficial, mainly as they have to resemble the nature of bacteria. Still, unlike most bacterial cells, actinomycetes have thin cells with a prokaryotic nucleoid and a peptidoglycan cell wall.

Mycoplasma

Plant endophytes have also been reported to be Mycoplasma species. Endophytic mycoplasma species have been shown to have a symbiotic interaction with certain red algae. Fungi are a heterotrophic category of organisms with diverse life cycles and symbiotic interactions with a wide range of autotrophic creatures. Many antibiotic substances have been isolated from endophytic actinomycetes. Streptomyces is a dominating genus that is usually isolated as endophytic actinomycetes.

Fungi

Fungi are a heterotrophic category of creatures with a diversity of life cycles and symbiotic interactions with a broad range of autotrophic species.

Conclusion

 Endophytes are a diverse group of microorganisms with distinct life histories: those that grow saprophytically on dead or senescing tissue after an endophytic growth phase.Endophytes are a poorly understood category of bacteria that can synthesize bioactive substances that can be utilized to battle various infections. These are reliable sources of bioactive and chemically novel molecules, making them suitable for innovative drug development. Biotransformation processes have several applications, including the synthesis of numerous bioactive substances such as antimicrobial (vanillin, essential oils), antifungal and antiviral (alkaloids), antioxidant (eugenol), anti-inflammatory (cineole), and so on. It is critical to examine and emphasize  past triumphs, ongoing research, and recent breakthroughs in endophytic microbe research to call the scientific community’s attention to this burgeoning topic.Endophyte bacterias are available in the environment in many forms, which generate a variety of bioactive metabolites, such as antibacterial and anticancer chemicals, with 76 percent of them identified from a single species, Streptomyces.