Purification and biochemical characterization of a thermostable, alkaliphilic, extracellular α-amylase from Bacillus subtilis DM-03, a strain isolated from the traditional fermented food of India

Efficacy of the Fruit and Vegetable Peels as Substrates for the Growth and Production of α-Amylases in Marine Actinobacteria

Enzymes from haloalkaliphilic microorganisms have recently focused attention on their potential and suitability in various applications. In this study, the growth and production of extracellular amylases in the marine actinomycetes, using kitchen waste as the raw starch source, have been investigated. Actinobacteria were isolated from the seawater of the Kachhighadi Coast near Dwarika, Gujarat. Seven Actinobacterial isolates of pre-monsoon, monsoon, and post-monsoon seasons belonging to different strains of Nocardiopsis genera were screened and selected for amylase production. The amylase production was initially assessed on the solid media supplemented with the extracts of different fruits and vegetable peels as a substrate by agar plate assay. The strains Kh-2(13), Kh-2(1), and Kh-3(12) produced maximum amylase with potato peel as a substrate, while no significant differences were found with the media containing other peels. Nevertheless, all strains produced amylases at a significant level with other raw substrates as well. For the optimization of the growth and enzyme production, the selected two isolates Kh-2(13) and Kh-3(12) of the monsoon and winter seasons were cultivated in a liquid medium under the submerged fermentation conditions, with potato peel as a substrate. In both organisms, the optimum amylase production was observed in the stationary phase of growth. For amylase production, the effect of different physical and chemical parameters was evaluated. The optimum growth and amylase production was achieved in 2% inoculum size, at pH 8.0, 28℃, and 5% salt concentration. On the basis of the amylase production index (API) (a ratio of the amylase units and cell growth), both isolates produced significant amylase with the only extract of potato peels, without any other supplements. The trends further indicated that while additional complex sources, such as yeast extract and peptone can enhance the cell growth of the actinobacteria, the amylase production remained unaltered. The study projects the significance of waste raw materials for the production of enzymes in extremophilic microorganisms.

Exploring microbial diversity in hot springs of Surajkund, India through 16S rRNA analysis and thermozyme characterization from endogenous isolates

Hot springs are a valuable source of biologically significant chemicals due to their high microbial diversity. To investigate the possibilities for industrial uses of these bacteria, researchers collected water and sediment samples from variety of hot springs. Our investigation employed both culture-dependent and culture-independent techniques, including 16S-based marker gene analysis of the microbiota from the hot springs of Surajkund, Jharkhand. In addition, we cultivated thermophilic isolates and screened for their ability to produce amylase, xylanase, and cellulase. After the optimized production of amylase the enzyme was partially purified and characterized using UPLC, DLS-ZP, and TGA. The retention time for the amylase was observed to be around 0.5 min. We confirmed the stability of the amylase at higher temperatures through observation of a steady thermo gravimetric profile at 400 °C. One of the thermophilic isolates obtained from the kund, demonstrated the potential to degrade lignocellulosic agricultural waste.

Isolation, Extraction, Purification, and Molecular Characterization for Thermostable α-Amylase from Locally Isolated Bacillus Species in Sudan

The aim of this study was to isolate some soil bacteria strain that produced α-amylase and subsequent extraction and purification. One hundred soil samples were collected from different geographical areas in Khartoum State such as north Omdurman, Toti Island, and Soba. Samples were analyzed for starch hydrolyzing bacteria. Among several bacteria isolated, Bacillus cereus and Bacillus licheniformis were identified as active α-amylase producers. Both bacteria showed a large zone of clearance of 20 mm when grown on starch-agar plates. The identity was conducted using biochemical characterization and confirmed by sequencing their 16S-rDNA. The constitutive nature of amylase was proved by amplification of the amylase gene from the genome of B. licheniformis. The α-amylase activity from the spent medium of B. cereus and B. licheniformis was optimized at pH 8.0 and temperature of 45°C and 65°C, respectively. The α-amylase produced by both bacteria is alkalophilic and thermophilic. The experiments confirmed that B. licheniformis can be a good source of amylase for industrial applications in Sudan.

Acid stable α-amylase from Pseudomonas balearica VITPS19-Production, purification and characterization

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α – Amylase was produced from a rhizobacteria Pseudomonas balearica VITPS19.

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One factor at a time method (OFAT) was employed to optimize the α –amylase production.

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Three step purification of α – amylase from the fermentation broth.

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Determining the optimal conditions for enzyme activity.

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Estimation of the enzymatic kinetic parameters of the α-amylase.

In the present study, α-amylase from Pseudomonas balearica VITPS19 isolated from Kolathur, Tamil Nadu, India was studied. Initially, one factor at a time (OFAT) approach was used to optimize the medium parameters like pH, temperature, carbon and nitrogen sources and the presence of metal ions to enhance the amylase activity. After the optimization, 6.5-fold increase in the enzyme production was observed. Enzyme purification was carried out in three stages. The molecular weight of purified α-amylase was estimated to be 47 kDa.The optimum activity for the purified enzyme was observed at pH 6 in 0.1 M phosphate buffer at 25 ± 2 °C and the activity is enhanced in the presence of ions like Mn²⁺, Mo⁶⁺, Na⁺, Mg²⁺and Zn²⁺ and was inhibited in the presence of Hg²⁺ ions. Compounds such as Sodium dodecyl sulfate (SDS), Ethylenediaminetetraacetic acid (EDTA), urea and β- mercaptoethanol reduced the amylase activity. The K_m and V_max of the α-amylase was estimated to be 45.23 mM and 20.83 U/mL, respectively.

Optimizing and purifying extracellular amylase from soil bacteria to inhibit clinical biofilm-forming bacteria

Background

Bacterial biofilms have become a major threat to human health. The objective of this study was to isolate amylase-producing bacteria from soil to determine the overall inhibition of certain pathogenic bacterial biofilms.

Methods

We used serial dilution and the streaking method to obtain a total of 75 positive amylase isolates. The starch-agar plate method was used to screen the amylolytic activities of these isolates, and we used morphological and biochemical methods to characterize the isolates. Optimal conditions for amylase production and purification using Sephadex G-200 and SDS-PAGE were monitored. We screened these isolates’ antagonistic activities and the purified amylase against pathogenic and multi-drug-resistant human bacteria using the agar disk diffusion method. Some standard antibiotics were controlled according to their degree of sensitivity. Finally, we used spectrophotometric methods to screen the antibiofilm 24 and 48 h after application of filtering and purifying enzymes in order to determine its efficacy at human pathogenic bacteria.

Results

The isolated Bacillus species were Bacillus megaterium (26.7%), Bacillus subtilis (16%), Bacillus cereus (13.3%), Bacillus thuringiesis (10.7%), Bacillus lentus (10.7%), Bacillus mycoides (5.3%), Bacillus alvei (5.3%), Bacillus polymyxa (4%), Bacillus circulans (4%), and Micrococcus roseus (4%). Interestingly, all isolates showed a high antagonism to target pathogens. B. alevi had the highest recorded activity (48 mm) and B. polymyxa had the lowest recorded activity (12 mm) against Staphylococcus aureus (MRSA) and Escherichia coli, respectively. On the other hand, we detected no antibacterial activity for purified amylase. The supernatant of the isolated amylase-producing bacteria and its purified amylase showed significant inhibition for biofilm: 93.7% and 78.8%, respectively. This suggests that supernatant and purified amylase may be effective for clinical and environmental biofilm control.

Discussion

Our results showed that soil bacterial isolates such as Bacillus sp. supernatant and its purified amylase are good antibiofilm tools that can inhibit multidrug-resistant former strains. They could be beneficial for pharmaceutical use. While purified amylase was effective as an antibiofilm, the isolated supernatant showed better results.

Production of a novel α-amylase by Bacillus atrophaeus NRC1 isolated from honey: Purification and characterization

Different bacterial isolates with amylolytic activity were insulated from various honey samples. The most active isolate was identified by the molecular 16SrRNA sequence technique as Bacillus atrophaeus NRC1. The bacterium showed maximum amylase production under optimum culture conditions at pH 6.0, 40 °C and after 24 h incubation. Two amylase isoenzymes (AmyI and AmyII) from Bacillus atrophaeus NRC1 have been purified to homogeneity by using ammonium sulfate precipitation, Sephacryl S-200 and DEAE-Sepharose chromatography. The major isoenzyme, AmyI, had a specific activity 4635 U/mg proteins with molecular weight of 61 kDa using SDS-PAGE electrophoresis. The maximum activity of AmyI against starch was determined at pH 6.0 and 50 °C. AmyI was stable up to 50 °C after incubation for 30 min, retained 65 and 23% of its activity at 60 and 70 °C, respectively. Pre-incubation with Ca²⁺, Mg²⁺ and Ba²⁺ cations for 30 min enhanced the enzyme activity; while it was completely inhibited by Hg²⁺. Varied inhibition degree of the enzyme activity was determined with K⁺, Ni²⁺, Zn²⁺, Na²⁺ and Cu²⁺ ions. AmyI was inhibited by EDTA, PMSF and SDS, while it was activated by l-Cysteine-HCl and DTT. AmyI had the ability to degrade starch, amylopectin, glycogen, amylose and lacked the affinity towards β-1,4-linked xyloses.

Enhanced amylase production by a Bacillus subtilis strain under blue light-emitting diodes

A chemotrophic, aerobic bacterial strain, Bacillus subtilis B2, was used to produce amylase by submerged fermentation under different light sources. SDS-PAGE indicated that the 55 kDa enzyme belonged to the α-amylase group. B2 was incubated in basal media with 1% soluble starch (pH 7.0) under blue, green, red, and white light-emitting diodes (LEDs), and white fluorescent light. Fermentation under blue LEDs maximized amylase production (180.59 ± 1.6 U/mL at 24 h). Production at 48 h increased to 310.56 ± 1.6 U/mL with 5% glucose as a simple carbon source and to 300.51 ± 1.7 U/mL with 5% groundnut oil cake as an agricultural waste substrate. Activity and stability of the amylase were greatest at pH 7.0 and 45-55 °C. Na⁺, Ca²⁺, Mg²⁺, Co²⁺, Ba²⁺, and K⁺ increased activity, while Ni²⁺, Hg²⁺, Mn²⁺, Cu²⁺, Fe³⁺, and Zn²⁺ inhibited activity. EDTA, PMSF and DTNB reduced activity by 50% or more, while tetrafluoroethylene and 1,10-phenanthroline reduced activity by 30%. The amylase was highly tolerant of the surfactants, compatible with organic solvents, oxidizing agents and the reducing agents reduced activity. These properties suggest utility of amylase produced by B. subtilis B2 under blue LED-mediated fermentation for industrial applications.

Purification and Characterization of Thermostable and Detergent-Stable α-Amylase from Anoxybacillus sp. AH1

A thermostable and detergent-stable α-amylase from a newly isolated Anoxybacillus sp. AH1 was purified and characterized. Maximum enzyme production (1874.8 U/mL) was obtained at 24 h of incubation. The amylase was purified by using Sephadex G-75 gel filtration, after which an 18-fold increase in specific activity and a yield of 9% were achieved. The molecular mass of the purified enzyme was estimated at 85 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature values of the enzyme were 7.0 and 60 °C, respectively. The enzyme was highly stable in the presence of 30% glycerol, retaining 85% of its original activity at 60 °C within 120 min. Km and vmax values were 0.102 µmol and 0.929 µmol/min, respectively, using Lineweaver-Burk plot. The enzyme activity was increased by various detergents, but it was significantly inhibited in the presence of urea. Mg2+ and Ca2+ also significantly activated α-amylase, while Zn2+, Cu2+ and metal ion chelators ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline (phen) greatly inhibited the enzyme activity. α-Amylase activity was enhanced by β-mercaptoethanol (β-ME) and dithiothreitol (DTT) to a great extent, but inhibited by p-chloromercuribenzoic acid (PCMB). Iodoacetamide (IAA) and N-ethylmaleimide (NEM) had a slight, whereas phenylmethylsulfonyl fluoride (PMSF) had a strong inhibitory effect on the amylase activity.

Structural and physico-chemical characterization of a dirhamnolipid biosurfactant purified from Pseudomonas aeruginosa: application of crude biosurfactant in enhanced oil recovery

The present study describes the structural characterization and biotechnological application of a dirhamnolipid biosurfactant produced byPseudomonas aeruginosastrain NBTU-01 isolated from a petroleum oil-contaminated soil sample.

Biochemical features and kinetic properties of α-amylases from marine organisms

Marine organisms have the ability of producing enzymes with unique properties compared to those of the same enzymes from terrestrial organisms. α-Amylases are among the most important extracellular enzymes found in various groups of organisms such as plants, animals and microorganisms. They play important roles in their carbohydrates metabolism of each organism. Microbial production of α-amylases is more effective than other sources of the enzyme. Many microorganisms are known to produce α-amylase including bacteria, yeasts, fungi and actinomycetes. However, enzymes from fungal and bacterial sources have dominated applications in industrial sectors. This review deals with what is known about the kinetics, biochemical properties and applications of these enzymes that have only been found in them and not in other α-amylases, and discussing their mechanistic and regulatory implications.

Molecular Identification of a Newly Isolated Bacillus subtilis BI19 and Optimization of Production Conditions for Enhanced Production of Extracellular Amylase

A study was carried out with a newly isolated bacterial strain yielding extracellular amylase. The phylogenetic tree constructed on the basis of 16S rDNA gene sequences revealed this strain as clustered with the closest members of Bacillus sp. and identified as Bacillus subtilis BI19. The effect of various fermentation conditions on amylase production through shake-flask culture was investigated. Rice flour (1.25%) as a cheap natural carbon source was found to induce amylase production mostly. A combination of peptone and tryptone as organic and ammonium sulfate as inorganic nitrogen sources gave highest yield. Maximum production was obtained after 24 h of incubation at 37 °C with an initial medium pH 8.0. Addition of surfactants like Tween 80 (0.25 g/L) and sodium lauryl sulfate (0.2 g/L) resulted in 28% and 15% increase in enzyme production, respectively. Amylase production was 3.06 times higher when optimized production conditions were used. Optimum reaction temperature and pH for crude amylase activity were 50 °C and 6.0, respectively. The crude enzyme showed activity and stability over a fair range of temperature and pH. These results suggest that B. subtilis BI19 could be exploited for production of amylase at relatively low cost and time.

Optimization of Amylase Production from B. amyloliquefaciens (MTCC 1270) Using Solid State Fermentation

Demand for microbial amylase production persists because of its immense importance in wide spectrum industries. The present work has been initiated with a goal of optimization of solid state fermentation condition for amylase using agroindustrial waste and microbial strain like B. amyloliquefaciens (MTCC 1270). In an aim to improve the productivity of amylase, fermentation has been carried out in the presence of calcium (Ca(+2)), Nitrate (NO3 (-)), and chloride ions (Cl(-)) as well as in the presence of D-inositol and mannitol. Amylase needs calcium ion for the preservation of its structure, activity and stability that proves beneficial also for amylase production using solid state fermentation. The inclusion of ions and sugars in the SSF media is promising which can be explained by the protection offered by them against thermal decay of amylase at various incubation periods at 37°C.

Statistical optimization of culture conditions for milk-clotting enzyme production by bacillus amyloliquefaciens using wheat bran-an agro-industry waste

In order to improve the production of the milk-clotting enzyme under submerged fermentation, two statistical methods were applied to optimize the culture conditions of Bacillus amyloliquefaciens D4 using wheat bran as nutrient source. First, initial pH, agitation speed, and fermentation time were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, optimal conditions were obtained using the Box-Behnken method, which were as follows: initial pH 7.57, agitation speed 241 rpm, fermentation time 53.3 h. Under these conditions, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 1996.9 SU/mL, which was 2.92-fold higher than that of the initial culture conditions, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize culture conditions. The research can provide a reference for full utilization of wheat bran and the production of milk-clotting enzyme by B. amyloliquefaciens D4 under submerged fermentation.

Enzymatic conversions of starch

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry. Some sections are devoted to the fermentation of starch to ethanol and other products, and to the production of cyclodextrins, along with the properties of these products. Light is also shed on the enzymes involved in the digestion of starch in human and animal organisms. Enzymatic processes acting on starch are useful in structural studies of the substrates and in understanding the characteristics of digesting enzymes. One section presents the application of enzymes to these problems. The information that is included covers the period from the early 19th century up to 2009.

Production and partial characterization of extracellular amylase enzyme from Bacillus amyloliquefaciens P-001

Amylases are one of the most important enzymes in present-day biotechnology. The present study was concerned with the production and partial characterization of extracellular amylase from Bacillus amyloliquefaciens P-001. The effect of various fermentation conditions on amylase production through shake-flask culture was investigated. Enzyme production was induced by a variety of starchy substrate but corn flour was found to be a suitable natural source for maximum production. Tryptone and ammonium nitrate (0.2%) as nitrogen sources gave higher yield compared to other nitrogen sources. Maximum enzyme production was obtained after 48 hrs of incubation in a fermentation medium with initial pH 9.0 at 42°C under continuous agitation at 150 rpm. The size of inoculum was also optimized which was found to be 1% (v/v). Enzyme production was 2.43 times higher after optimizing the production conditions as compared to the basal media. Studies on crude amylase revealed that optimum pH, temperature and reaction time of enzyme activity was 6.5, 60°C and 40 minutes respectively. About 73% of the activity retained after heating the crude enzyme solution at 50°C for 30 min. The enzyme was activated by Ca²⁺ (relative activity 146.25%). It was strongly inhibited by Mn²⁺, Zn²⁺ and Cu²⁺, but less affected by Mg²⁺ and Fe²⁺.

Purification and characterization of novel α-amylase from Bacillus subtilis KIBGE HAS

Purification of extracellular α-amylase from Bacillus subtilis KIBGE HAS was carried out by ultrafiltration, ammonium sulfate precipitation and gel filtration chromatography. The enzyme was purified to homogeneity with 96.3-fold purification with specific activity of 13011 U/mg. The molecular weight of purified α-amylase was found to be 56,000 Da by SDS-PAGE. Characteristics of extracellular α-amylase showed that the enzyme had a Km and V (max) value of 2.68 mg/ml and 1773 U/ml, respectively. The optimum activity was observed at pH 7.5 in 0.1 M phosphate buffer at 50 °C. The amino acid composition of the enzyme showed that the enzyme is rich in neutral/non polar amino acids and less in acidic/polar and basic amino acids. The N-terminal protein sequence of 10 residues was found to be as Ser-Ser-Asn-Lys-Leu-Thr-Thr-Ser-Trp-Gly (S-S-N-K-L-T-T-S-W-G). Furthermore, the protein was not N-terminally blocked. The sequence of α-amylase from B. subtilis KIBGE HAS was a novel sequence and showed no homology to other reported α-amylases from Bacillus strain.

Extraction, Purification and Characterization of Thermostable, Alkaline Tolerant α-Amylase from Bacillus cereus

Thermostable alkaline α-amylase producing bacterium Bacilluscereus strain isolated from Cuddalore harbour waters grew maximally in both shake flask and fermentor, and produced α-amylase at 35°C, pH 7.5 and 1.0% of substrate concentrations. α-Amylase activity was maximum at 65°C, pH 8.0, 89% of its activity was sustained even at pH 11.0. Added with MnCl(2,) α-amylase activity showed 4% increase but it was inhibited by EDTA. The molecular weight of the purified α-amylase is 42 kDa.

Biocontrol and other beneficial activities of Bacillus subtilis isolated from cowdung microflora

Bacillus subtilis strains isolated from cowdung (CD) had several beneficial attributes, which included biocontrol, plant growth promotion, sulphur (S) oxidation, phosphorus (P) solubilization and production of industrially important enzymes (amylase and cellulase). The B. subtilis strains from CD inhibited the in vitro growth of fungi, Fusarium oxysporum (25-34%) and Botryodiplodia theobromae (100%), isolated from the postharvest rots of yam (Dioscorea rotundata) tubers. Other than biocontrol, B. subtilis strains were able to promote root elongation in seedlings of Cicer arietinum up to 70-74% as compared to untreated seeds (control). B. subtilis strains had also the ability to oxidize elemental S to sulphate (2-15microgml(-1)) and showed distinct P-solubilization activity in vitro. In addition, the cultures showed cellulase activity in carboxy methyl cellulose medium (1.5-1.8mg of reducing sugar24h(-1)ml(-1)) and amylase activity in vitro.

Biochemical characterization of raw-starch-digesting alpha amylase purified from Bacillus amyloliquefaciens

Alpha amylase (E.C. 3.2.1.1) of Bacillus amyloliquefaciens produced by submerged fermentation was purified to near homogeneity by ion exchange chromatography. Through the process 38.6-fold increase in purity with a specific activity of 72 U/mg proteins was obtained. The apparent molecular weight of the purified enzyme was found to be 58 kDa by SDS-PAGE. The enzyme was relatively stable between pH 5.0-8.0 and temperature between 50 and 60 degrees C. The enzyme did not show any obligate requirement of metal ions but Ca2+ and Cu2+ enhanced the enzyme activity marginally and the thermostability was enhanced in the presence of Ca2+ ions. The purified enzyme exhibited maximal substrate specificity for amylose and efficiency in digesting various raw starches. The K(m) and V(max) of the enzyme was determined using both amylose and soluble starch as substrate. The analysis of the hydrolyzed products of soluble starch by thin layer chromatography showed the yield of maltosaccharides after 6 h of hydrolysis.

Potential application of cyclic lipopeptide biosurfactants produced by Bacillus subtilis strains in laundry detergent formulations

AIMS

Crude cyclic lipopeptide (CLP) biosurfactants from two Bacillus subtilis strains (DM-03 and DM-04) were studied for their compatibility and stability with some locally available commercial laundry detergents.

METHODS AND RESULTS

CLP biosurfactants from both B. subtilis strains were stable over the pH range of 7.0-12.0, and heating them at 80 degrees C for 60 min did not result in any loss of their surface-active property. Crude CLP biosurfactants showed good emulsion formation capability with vegetable oils, and demonstrated excellent compatibility and stability with all the tested laundry detergents.

CONCLUSION

CLP biosurfactants from B. subtilis strains act additively with other components of the detergents to further improve the wash quality of detergents. The thermal resistance and extreme alkaline pH stability of B. subtilis CLP biosurfactants favour their inclusion in laundry detergent formulations.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study has great significance because it is already known that microbial biosurfactants are considered safer alternative to chemical or synthetic surfactants owing to lower toxicity, ease of biodegradability and low ecological impact. The present study provides further evidence that CLP biosurfactants from B. subtilis strains can be employed in laundry detergents.

Assessment of mosquito larvicidal potency of cyclic lipopeptides produced by Bacillus subtilis strains

In this study, mosquito larvicidal potency of cyclic lipopeptides (CLPs) secreted by two Bacillus subtilis strains were determined. LC50 of the crude CLPs secreted by B. subtilis DM-03 and DM-04 strains against third instar larvae of Culex quinquefasciatus was 120.0+/-5.0 and 300.0+/-8.0mg/l respectively post 24 h of treatment. Physico-chemical factors such as pH of water, incubation temperature, heating and exposure to sunlight hardly influenced the larvicidal potency of these CLPs. Present study provided the evidence that B. subtilis lipopeptides were safe to Indian major carp Labeo rohita, a non-target aquatic organism. These properties of B. subtilis CLPs can be exploited for the formulation of a safer, novel biopesticide for effective control of mosquito larvae.

Characterization of biochemical properties and biological activities of biosurfactants produced by Pseudomonas aeruginosa mucoid and non-mucoid strains isolated from hydrocarbon-contaminated soil samples

Biochemical and pharmacological properties of biosurfactants produced at 45 degrees C temperature by Pseudomonas aeruginosa mucoid (M) and non-mucoid (NM) strains, isolated from hydrocarbon-contaminated soil samples, were characterized. Both the strains secreted appreciable amount of biosurfactants (5.0-6.5 g/l), responsible for the reduction of surface tension of the medium from 68 to 29 +/- 0.5 mN/m post 96 h of growth. Maximum yield of biosurfactants was observed following the supplementation of NH(4)Cl and glycerol as nitrogenous source and carbon source, respectively. These thermostable biosurfactants exhibited strong emulsifying property and could release appreciable amount of oil from saturated sand-pack column. Pharmacological characterization of these biosurfactants revealed that they induced dose-dependent hemolysis and coagulation of platelet-poor plasma but were non-detrimental to chicken lung, liver, heart and kidney tissues. Our study has documented that biosurfactants from P. aeruginosa M and NM strains could be exploited for use in petroleum sectors as well in pharmaceutical industries.

Correlation between diverse cyclic lipopeptides production and regulation of growth and substrate utilization by Bacillus subtilis strains in a particular habitat

The two Bacillus subtilis strains (DM-03 and DM-04) were isolated from two extremely different habitats; one from the traditional fermented food and another one from a petroleum contaminated soil sample. These strains produced quantitatively and qualitatively different cyclic lipopeptides isoforms under laboratory culture conditions. MALDI-TOF mass spectral analysis revealed that lipopeptide profile varied according to the producing B. subtilis strains; iturins and surfactins isoforms were pre-dominant cyclic lipopeptides produced by B. subtilis DM-03 and DM-04 strains, respectively. A comparative study showed that these strains possessed distinct preferences for the carbon and nitrogen substrates, temperature and pH for optimal growth and biosurfactant production. Our study documented that the cyclic lipopeptide isoforms produced by the respective strains played an important role in the utilization of available hydrophobic substrate(s) from their natural habitats and conferred some kind of competitive advantage to the producing B. subtilis strains in their parent ecological niche.