Microbial surfactants are amphiphilic surface-active substances aid to reduce surface and interfacial tensions by accumulating between two fluid phases. They can be generically classified as low or high molecular weight biosurfactants based on their molecular weight, whilst overall chemical makeup determines whether they are neutral or anionic molecules. They demonstrate a variety of fundamental characteristics, including the lowering of surface tension, emulsification, adsorption, micelle formation, etc. Microbial genera like Bacillus spp., Pseudomonas spp., Candida spp., and Pseudozyma spp. are studied extensively for their production. The type of biosurfactant produced is reliant on the substrate utilized and the pathway pursued by the generating microorganisms. Some advantages of biosurfactants over synthetic surfactants comprise biodegradability, low toxicity, bioavailability, specificity of action, structural diversity, and effectiveness in harsh environments. Biosurfactants are physiologically crucial molecules for producing microorganisms which help the cells to grasp substrates in adverse conditions and also have antimicrobial, anti-adhesive, and antioxidant properties. Biosurfactants are in high demand as a potential product in industries like petroleum, cosmetics, detergents, agriculture, medicine, and food due to their beneficial properties. Biosurfactants are the significant natural biodegradable substances employed to replace the chemical surfactants on a global scale in order to make a cleaner and more sustainable environment.
A natural bacterial isolate that shows multiple plant growth-promoting activities was isolated from fermented panchagavya (a mixture of five indigenous cow products). It is a gram-positive, endospore-forming bacteria identified as Bacillus sp. PG-8 by 16S rRNA gene sequencing. The Bacillus sp. PG-8 have shown multiple plant growth-promoting activities as indole acetic acid (2.78 μg/ml), gibberellic acid (0.7 mg/ml), ammonia (6.51 μmol/ml), exopolysaccharide (2.6% w/v) production, and phosphate solubilization (198.27 μg/ml). The Bacillus sp. PG-8 has ability to survive under the abiotic stress conditions such as temperature (28–46°C), pH (5.0–12.0), salt (0.5–20.0% w/v NaCl), and osmotic resistance (1–10% w/v PEG-6000). Due to its diverse characteristics, the effect of Bacillus sp. PG-8 was tested on Arachis hypogea (groundnut). The seeds treated with Bacillus sp. PG-8 demonstrated a 70% germination rate with seedling vigor indexes of 154. In pot study, Arachis hypogea growth showed 1.38, 1.38, 1.32, 1.39, and 1.52 times increase in root hair number, leaf numbers, leaf width, leaf length, and leaf area, respectively. The addition of Bacillus sp. PG-8 culture to the Arachis hypogea plant resulted in a significant improvement in plant growth. Bacillus sp. PG-8 is a spore producer with stress tolerance and multiple plant growth-promoting properties, which makes it a potential liquid biofertilizer candidate.
Gibberellic acid production using Fusarium moniliforme, isolated from wilted sugarcane plant has been investigated by solid state fermentation (SSF). The gibberellic acid production of 154mgm/gm was obtained on commercial wheat bran (CWB) mineral salt acid bed in 500 ml flasks after 168 h incubation. The gibberellic acid production rate was about 0.6 to 0.9 mgm/gm/hr during 96 to 168 h. Different carbon sources namely sucrose, lactose, maltose, soluble starch, glycerol, wheat flour and maize flour were tested as an additional substrate along with CWB at the concentration of 25% w/w or v/w base to observe its effects on gibberellic acid production. Soluble starch has been proved the best additional carbon source for gibberellic acid production, which yielded 1160mgm/gm of gibberellic acid after 168 h. Similarly, various nitrogen sources namely NH4Cl, NH4NO3, (NH4)2SO4, (NH4)MoO4 and urea were tested as an additional substrate at the concentration of 0.07% w/w of CWB. Urea was proved as the best nitrogen source which yielded 532 mgm/gm of gibberellic acid after 168 h incubation. We have observed about 7.5-fold and 3.5-fold increase in gibberellic acid production upon addition of soluble starch and urea respectively, in CWB using Fusarium moniliforme.Int J Appl Sci Biotechnol, Vol 4(3): 402-407
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