Actinobacteria include a group of branching unicellular microorganisms, most of which are known as substrates and air and become mycelium by forming aerobic. They reproduce by binary fission, producing spores or conidia, and the sporulation of actinobacteria is through fragmentation and segmentation or formation of conidia. Its morphological appearance is compact, usually leathery, gives a conical appearance with a dry surface on the culture medium, and is often covered with air mycelium.
Mycelium in the air
Airborne mycelium is usually thicker than the substrate mycelium. It shows enough differentiation that various isolates can be divided into several groups with similar morphological characteristics under fixed conditions. This has been established as one of the most important criteria for classification of the breed. Streptomyces develops into species with structure (cottony, velvety, or powdery), the formation of rings or concentric regions, and pigmentation.
Alt Tabaka Miselyum
The substrate mycelium of the actinobacterium differs in size, shape and thickness. Its color ranges from white or almost colorless to yellow, brown, red, pink, orange, green or black.
Morphology has been an important feature for the protection of isolates of actinobacteria especially streptomyces species used in the first definitions. This streptomyces project (ISP) is done using a variety of standard culture media, including international. For non-streptomycetes or rare actinobacteria, ATCC Media No. Strains retained above 172 were used. Various morphological observations such as germination of spores, elongation and branching of vegetative mycelium, mycelium formation in air, air and substrate mycelium color, and pigment production have been used to identify actinobacteria. Light microscopy was used to examine the formation of airborne and substrate mycelium, and a scanning electron microscope was used to examine spores, spore surface and structure.
Another interesting application of actinobacteria is the use of their secondary metabolites as herbicides against unwanted weeds and weeds. Streptomyces produces herbicides and herbimicins that control monocotyledonous and dicotyledonous weeds. Anisomycin produced by streptomyces sp is a type of growth inhibitor for annual grassy weeds such as common crab grass and broadleaf weeds, also anisomycin can destroy the plants’ ability to synthesize chlorophyll. Similarly, bialaphos streptomyces viridochromogenes, a metabolite, is widely used to control annual and perennial grassy or broadleaf weeds by inhibiting glutamine synthesis.
While anisomycin can kill small shrub seedlings above 50 ppm, below 12.5 ppm can inhibit root growth. Synthesis can accumulate ammonia and control photosynthetic phosphorylation, causing plant death. S. hygroscopicus produces carbocyclic coformycin and hydantocide, which can increase ATP content and decrease aclenylosuccinate synthetase and inhibit protein synthesis. Dhanasekaran and his team found that streptomyces Echinochilora crusgalli has the capacity to inhibit growth.
Biological surfactants are microbially derived compounds that share the hydrophilic and hydrophobic moieties that are surfactants. Compared to chemically derived surfactants, bio surfactants are independent of mineral oil as raw material. They are also easily biodegradable and can be produced at low temperatures. Biological surfactants can be applied in a variety of fields such as the food, cosmetics, textile, varnish, pharmaceutical, mining and oil recovery industries. Among the best described bio-surfactants are glucose-based glycolipids, most of which have a hydrophilic backbone of glycosidic linked glucose units forming a trehalose moiety.
Germ-focused pigments are of great importance for the production of synthetic paints, as they have some limitations such as the use of hazardous chemicals, worker safety concerns and the generation of hazardous wastes. In particular, actinobacteria are characterized by the production of various pigments in natural or synthetic environments and are considered an important cultural trait in identifying organisms. Any phenotypic changes caused by environmental influences help actinobacteria as they have distinctive colonial morphologies and produce a variety of pigments called hyphae and air branching filaments that give them a characteristic hairy appearance.
These pigments usually come in a variety of shades of blue, purple, red, rose, yellow, green, brown, and black, and they can be dissolved in medium or kept in mycelium. Pigments produced by it can be atreptomycesendopigments or exopigments. Sometimes different antibiotics produced by actinobacteria are considered pigments. Little is known about the exact chemical makeup of the pigments, as pigment formation is affected by the pH of the environment, aeration, growth temperature, carbon and nitrogen sources. Its formation is also linked to respiratory mechanisms, defense mechanisms, and ultraviolet protection. These microbes also have the ability to synthesize and secrete dark pigments, melanin or melanoid, which are considered a useful criterion for taxonomic studies. The textile industry produces and uses about 1.3 million tons of dyes, pigments and dye precursors worth about $ 23 billion.
Nanoparticles are of great scientific interest as they fill the gap between bulk materials and atomic or molecular structures. Generally, chemical methods are low cost for high volume, but disadvantages include contamination from precursor chemicals, the use of toxic solvents, and the formation of hazardous by-products. Therefore, there is an increasing need to develop highly efficient, low cost, non-toxic and environmentally friendly procedures for the synthesis of metallic nanoparticles. Also, biological approach gains importance for the synthesis of nanoparticles. In fact, actinobacteria are effective nanoparticle producers with a range of biological properties such as antibacterial, antifungal, anticancer, antibiotic, antimalarial, antiparasitic and antioxidant.
Streptomyces and arthrobacter have been studied as possible nanofactures for the development of clean and non-toxic methods of synthesis of silver and gold nanoparticles. A new example of silver nanoparticle synthesis from an actinobacterium, streptomyces sp GRD, has been made by Gopinath et al. Ranjani and his team observed the diversity of silver nanoparticles synthesizing actinobacteria from the marine environment. They contain 25 isolates of 49 synthesized silver nanoparticles, including Streptomyces sp, nocardiopsis sp, Kitasatosporia sp, actinopolisporalar sp, thermoactinomyces sp, sakalosiburatin sp, and thermomonospora sp.
The widespread use of chemical insecticides to control malaria, filaria, dengue fever, chickens, Japanese encephalitis and other mosquitoes has damaged the environment and resulted in the development of resistance in vector mosquitoes. Accordingly, various biological control agents have gained importance with numerous advantages over chemical insecticides. At very low doses, these biolarvicides are highly effective against mosquito larvae and are completely safe for other non-target organisms, the environment, humans and wildlife. Various types of microorganisms, including fungi, bacteria, and nematodes, have been reported as strategies to control vectors biologically. Specifically, actinobacteria produce many important bioactive compounds of high commercial value and continue to be routinely screened for new bioactive substances.
Extracellular secondary metabolites were produced from 35 different actinobacterial isolates. Dhanasekaran et al., Anopheles mosquito larvae isolates have high larvicidal activity against streptomyces sp, streptosporangium sp and micropolis sp. Rajesh et al, silver nanoparticles streptomyces sp. The GRD cell filtrate and the observed larvicidal activity are the vectors responsible for the transmission of Aedes and Culex Dengue fever and filariasis. Rajesh et al., In their study of the larvicidal effect of actinobacterial extracts, found 1000 ppm concentration of culex larva and isolate. Streptomyces sp. KA13-3 showed 100% and streptomyces sp KA25-A 90% mortality. Other secondary metabolites from actinobacteria namely tetranectin, avermectin, macrotetrolides and flavonoids have been found to be toxic to mosquitoes.
Actinobacterial human and animal diseases
Actinobacteria have proven to be causative agents of many human and animal infections, including a number of common and extensively studied diseases such as diphtheria, tuberculosis, and leprosy. There are also a wide variety of lesser known infections, some of which prove to be clinically more important than previously thought, such as actinomycosis and nocardiosis. In addition, it becomes increasingly prominent that actinomyces plays a role in the etiology of caries and periodontal disease.
As a result, actinobacteria are one of the dominant groups of microorganisms that produce industrially important secondary metabolites, and a wide range of antibiotics on the market are derived from actinobacteria. Products such as enzymes, herbicides, vitamins, pigments, larvicides, phytohormones, and surfactants are produced by these few species of actinobacteria with great commercial value. They are able to break down a wide variety of hydrocarbons, pesticides and feather waste, and their metabolic potential offers a powerful field for research. However, most of its rare strains were neither discovered from undiscovered locations nor used for their biotechnological and industrial potential. Therefore, studies of unique ecological environments can produce molecules that could be future precursors of green technology.
Writer: Ozlem Guvenc Agaoglu