Endophytic bacteria isolated from Urtica dioica L.- preliminary screening for enzyme and polyphenols production.

Endophytes, especially those isolated from herbal plants, may act as a reservoir of a variety of secondary metabolites exhibiting biological activity. Some endophytes express the ability to produce the same bioactive compounds as their plant hosts, making them a more sustainable industrial supply of these substances. Urtica dioica L. (common stinging nettle) is a synanthropic plant that is widely used in herbal medicine due to the diversity of bioactive chemicals it contains, e.g., polyphenols, which demonstrate anti-inflammatory, antioxidant, and anti-cancerous capabilities. This study aimed at isolating endophytic bacteria from stinging nettles for their bioactive compounds. The endophytic isolates were identified by both biochemical and molecular methods (16S rRNA) and investigated for enzymes, biosurfactants, and polyphenols production. Each of the isolated bacterial strains was capable of producing biosurfactants and polyphenols. However, three of the isolated endophytes, identified as two strains of Bacillus cereus and one strain of Bacillus mycoides, possessed the greatest capacity to produce biosurfactants and polyphenols. The derivatized extracts from culture liquid showed the 1.633 mol l-1 (9.691 mg l-1) concentration of polyphenol compounds. Therefore, the present study signifies that endophytic B. cereus and B. mycoides isolated from Urtica dioica L. could be a potential source of biosurfactants and polyphenols. However, further study is required to understand the mechanism of the process and achieve efficient polyphenol production by endophytic bacteria.

Biosurfactant from endophytic Bacillus pumilus 2A: physicochemical characterization, production and optimization and potential for plant growth promotion.

BACKGROUND: Microbial surfactants called biosurfactants, thanks to their high biodegradability, low toxicity and stability can be used not only in bioremediation and oil processing, but also in the food and cosmetic industries, and even in medicine. However, the high production costs of microbial surfactants and low efficiency limit their large-scale production. This requires optimization of management conditions, including the possibility of using waste as a carbon source, such as food processing by-products. This papers describes the production and characterization of the biosurfactant obtained from the endophytic bacterial strain Bacillus pumilus 2A grown on various by-products of food processing and its potential applications in supporting plant growth. Four different carbon and nitrogen sources, pH, inoculum concentration and temperature were optimized within Taguchi method. RESULTS: Optimization of bioprocess within Taguchi method and experimental analysis revealed that the optimal conditions for biosurfactant production were brewer's spent grain (5% w/v), ammonium nitrate (1% w/v), pH of 6, 5% of inoculum, and temperature at 30 °C, leading to 6.8 g/L of biosurfactant. Based on gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy analysis produced biosurfactant was determined as glycolipid. Obtained biosurfactant has shown high and long term thermostability, surface tension of 47.7 mN/m, oil displacement of 8 cm and the emulsion index of 69.11%. The examined glycolipid, used in a concentration of 0.2% significantly enhanced growth of Phaseolus vulgaris L. (bean), Raphanus L. (radish), Beta vulgaris L. (beetroot). CONCLUSIONS: The endophytic Bacillus pumilus 2A produce glycolipid biosurfactant with high and long tem thermostability, what makes it useful for many purposes including food processing. The use of brewer's spent grain as the sole carbon source makes the production of biosurfactants profitable, and from an environmental point of view, it is an environmentally friendly way to remove food processing by products. Glycolipid produced by endophytic Bacillus pumilus 2A significantly improve growth of Phaseolus vulgaris L. (bean), Raphanus L. (radish), Beta vulgaris L. (beetroot). Obtained results provide new insight to the possible use of glycolipids as plant growth promoting agents.

Biodegradation of slop oil by endophytic Bacillus cereus EN18 coupled with lipase from Rhizomucor miehei (Palatase®).

Removal of slop oil, a by-product of oil refining, also obtained in cleaning up of oil tanks and filters is a difficult issue. High content of hydrocarbons (C3-C40) and other organic compounds makes this waste difficult to eliminate from the environment. The purpose of this investigation was to combine bacterial degradation by endophytic Bacillus cereus EN18 with biotransformation performed using lipase enzyme preparation (Palatase®) to remove recalcitrant compounds present in slop oil from the environment. Endophytic B. cereus EN18 was able to biodegrade up to 40% of slop oil while supplementation with lipase improved the efficiency of contamination removal in about one third. Also the use of lipase enzyme preparation resulted in higher microbial activity of B. cereus EN18 bacterial strain, as well as higher concentration of fatty acids in the culture medium, which indicates higher degradation efficiency. Obtained results suggest that lipase preparation from Rhizomucor miehei (Palatase®) may be a useful agent to improve microbial degradation of recalcitrant pollutants, like slop oil in water environments. GC and spectrometric analysis revealed that hydrocarbons from slop oil were effectively degraded while using both microbial degradation and lipase catalysis.

Biosurfactant production and hydrocarbon degradation activity of endophytic bacteria isolated from Chelidonium majus L.

BACKGROUND: The process of plant growth in the contaminated environment is often inhibited and entails the neutralization of harmful compounds. To reduce the negative impact of harmful compounds microorganisms produce unique compounds called biosurfactants. This paper describes the potential of culturable endophytic microorganisms from synanthropic plant-Chelidonium majus L. for the production of biosurfactants, as indirect plant promoting factors as well as their degradation activity. Emulsifying activity and degradation potential of tested strains were assessed by cultivation of isolates in the presence of diesel oil and waste engine oil. RESULTS: Ten bacterial strain were isolated. Analysis of emulsifying activity revealed that all isolates possessed the ability for biosurfactant production. However, one of the isolated endophytes-2A, identified as Bacillus pumilus, exhibited the highest emulsifying activity (OD500 1.96). The same strain has shown very high degradation potential, both for diesel oil and waste engine oil hydrocarbons. Results obtained with the Phytotoxkit tests revealed that the addition of biosurfactant isolated from B. pumilus 2A strain resulted in stimulation of seed germination in soil contaminated with diesel oil (137%) and waste engine oil (120%). Positive impact of the biosurfactant produced by B. pumilus 2A on the growth of Sinapis alba in hydrocarbons contaminated soil was demonstrated. CONCLUSIONS: The endophytic strain identified as Bacillus pumilus 2A produce biosurfactant that is able to act as plant-growth promoting agent. Endophytic bacteria isolated from Chelidonium majus L. exhibit potential for hydrocarbons degradation and biosurfactant production. These properties provide promising perspectives for application of biosurfactants as potential agents for bioremediation of environment contaminated with hydrocarbons.