Biosurfactant Production by Azotobacter chroococcum Isolated from the Marine Environment

Preliminary characterization of a biosurfactant-producing Azotobacter chroococcum isolated from marine environment showed maximum biomass and biosurfactant production at 120 and 132 h, respectively, at pH 8.0, 38°C, and 30‰ salinity utilizing a 2% carbon substrate. It grew and produced biosurfactant on crude oil, waste motor lubricant oil, and peanut oil cake. Peanut oil cake gave the highest biosurfactant production (4.6 mg/mL) under fermentation conditions. The biosurfactant product emulsified waste motor lubricant oil, crude oil, diesel, kerosene, naphthalene, anthracene, and xylene. Preliminary characterization of the biosurfactant using biochemical, Fourier transform infrared spectroscopy, and mass spectral analysis indicated that the biosurfactant was a lipopeptide with percentage lipid and protein proportion of 31.3:68.7.     

Optimization, purification and characterization of novel thermostable, haloalkaline, solvent stable protease from Bacillus halodurans CAS6 using marine shellfish wastes: a potential additive for detergent and antioxidant synthesis

A protease producing marine bacterium, Bacillus halodurans CAS6 isolated from marine sediments, was found to produce higher enzyme by utilizing shrimp shell powder. Optimum culture conditions for protease production were 50 °C, pH 9.0, 30 % NaCl and 1 % shrimp shell powder (SSP) and the protease purified with a specific activity of 509.84 U/mg. The enzyme retained 100 % of its original activity even at 70 °C, pH 10.0 and 30 % NaCl for 1 h. The purified protease exhibited higher stability when treated with ionic, non-ionic (72–94 %) and commercial detergents (76–88 %), and organic solvents (88–126 %). Significant blood stain removal activity was found with the enzyme in washing experiments. The culture supernatant supplemented with 1 % SSP showed 93.67 ± 2.52 % scavenging activity and FT-IR analysis of the reaction mixture confirmed the presence of antioxidants such as cyclohexane and cyclic depsipeptide with aliphatic amino groups. These remarkable qualities found with this enzyme produced by Bacillus halodurans CAS6 could make this as an ideal candidate to develop the industrial process for bioconversion of marine wastes and antioxidant synthesis.     

Production and characterization of a glycolipid biosurfactant from Bacillus megaterium using economically cheaper sources

Criteria selected for screening of biosurfactant production by Bacillus megaterium were hemolytic assay, bacterial cell hydrophobicity and the drop-collapse test. The data on hemolytic activity, bacterial cell adherence with crude oil and the drop-collapse test confirmed the biosurfactant-producing ability of the strain. Accordingly, the strain was cultured at different temperatures, pH values, salinity and substrate (crude oil) concentration in mineral salt medium to establish the optimum culture conditions, and it was shown that 38°C, 2.0% of substrate concentration, pH 8.0 and 30‰ of salt concentration were optimal for maximum growth and biosurfactant production. Laboratory scale biosurfactant production in a fermentor was done with crude oil and cheaper carbon sources like waste motor lubricant oil and peanut oil cake, and the highest biosurfactant production was found with peanut oil cake. Characterization of partially purified biosurfactant inferred that it was a glycolipid with emulsification potential of waste motor lubricant oil, crude oil, peanut oil, diesel, kerosene, naphthalene, anthracene and xylene.     

Biosurfactant production by Corynebacterium kutscheri from waste motor lubricant oil and peanut oil cake

AIM: Production and characterization of biosurfactant from renewable sources. METHODS AND RESULTS: Biosurfactant production was carried out in 3-l fermentor using waste motor lubricant oil and peanut oil cake. Maximum biomass (9.8 mg ml(-l)) and biosurfactant production (6.4 mg ml(-l)) occurred with peanut oil cake at 120 and 132 h, respectively. Chemical characterization of the biosurfactant revealed that it is a glycolipopeptide with chemical composition of carbohydrate (40%), lipid (27%) and protein (29%). The biosurfactant is able to emulsify waste motor lubricant oil, crude oil, peanut oil, kerosene, diesel, xylene, naphthalene and anthracene; the emulsification activity was comparatively higher than the activity found with Triton X-100. CONCLUSION: This study indicates the possibility of biosurfactant production using renewable, relatively inexpensive and easily available resources like waste motor lubricant oil and peanut oil cake. Emulsification activity found with the biosurfactant against different hydrocarbons showed the possibility of the application of biosurfactants against diverse hydrocarbon pollution. SIGNIFICANCE AND IMPACT OF THE STUDY: The data obtained from the study could be useful for large-scale biosurfactant production using economically cheaper substrates. Information obtained in emulsification activity and laboratory-scale experiment on bioremediation inferred that bioremediation of hydrocarbon-polluted sites may be treated with biosurfactants or the bacteria that produces it.     

Biosurfactant Production by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> from Renewable Resources

This study deals with production and characterization of biosurfactant from renewable resources by Pseudomonas aeruginosa. Biosurfactant production was carried out in 3L fermentor using waste motor lubricant oil and peanut oil cake. Maximum biomass (11.6 mg/ml) and biosurfactant production (8.6 mg/ml) occurred with peanut oil cake at 120 and 132 h respectively. Characterization of the biosurfactant revealed that, it is a lipopeptide with chemical composition of protein (50.2%) and lipid (49.8%). The biosurfactant (1 mg/ml) was able to emulsify waste motor lubricant oil, crude oil, peanut oil, kerosene, diesel, xylene, naphthalene and anthracene, comparatively the emulsification activity was higher than the activity found with Triton X-100 (1 mg/ml). Results obtained in the present study showed the possibility of biosurfactant production using renewable, relatively inexpensive and easily available resources. Emulsification activity found with the biosurfactant against different hydrocarbons showed its possible application in bioremediation of environments polluted with various hydrocarbons.     

Numerical Investigation on Elliptic Cylindrical Nanowire Hybrid Plasmonic Waveguide–Based Polarization Beam Splitter

A novel design of elliptic cylindrical nanowire hybrid plasmonic waveguide (ECNHPW)–based polarization beam splitter (PBS) is proposed. In the proposed design, the ECNHPW arm acts as an input port and a bar port; on the other hand, a regular silicon wire (RSW) arm acts as a cross port. By selecting the physical parameters of the proposed PBS accurately, the transverse electric (TE) mode is merely satisfied with the phase-matching condition. In contrast, the transverse magnetic (TM) mode does not propagate to the RSW arm. Consequently, the TM input mode goes directly to the ECNHPW arm, while the TE input mode in ECNHPW is coupled with RSW arm. As a result, the two different polarization modes are meritoriously separated, and they pass through two different arms. For the proposed PBS, the insertion loss (IL) of both polarizations lies below 1 dB. For TE input, the value of the polarization extinction ratio (PER) is 27.2 dB, and for TM input, it is 23.9 dB at 1550 nm operating wavelength. Further optimization is implemented by varying the wavelength, thickness of SiO₂, and the gap between the waveguides using the finite element method (FEM). The proposed PBS is designed with 150 nm bandwidth, high PER, and low IL, which can be suitable for photonic integrated circuits (PICs).

     

Effect of biosurfactant and fertilizer on biodegradation of crude oil by marine isolates of Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa

This study was conducted to investigate the effects of fertilizers and biosurfactants on biodegradation of crude oil by three marine bacterial isolates; Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa. Five sets of experiments were carried out in shake flask and microcosm conditions with crude oil as follows: Set 1-only bacterial cells added (no fertilizer and biosurfactant), Set 2-with additional fertilizer only, Set 3-with additional biosurfactant only, Set 4-with added biosurfactant + fertilizer, Set 5-with no bacterial cells added (control), all the above experimental sets were incubated for 168 h. The biosurfactant + fertilizer added Set 4, resulted in maximum crude oil degradation within shake flask and microcosm conditions. Among the three bacterial isolates, P. aeruginosa and biosurfactant produced by this strain resulted in maximum crude oil degradation compared to the other two bacterial strains investigated. Interestingly, when biosurfactant and bacterial cells were used (Set 3), significant oil biodegradation activity occurred and the difference between this treatment and that in Set 4 with added fertilizer + biosurfactant were only 4-5% higher degradation level in shake flask and 3.2-7% in microcosm experiments for all three bacterial strains used. It is concluded that, biosurfactants alone capable of promoting biodegradation to a large extent without added fertilizers, which will reduce the cost of bioremediation process and minimizes the dilution or wash away problems encountered when water soluble fertilizers used during bioremediation of aquatic environments.     

Application of biosurfactant produced from peanut oil cake by Lactobacillus delbrueckii in biodegradation of crude oil

Lactobacillus delbrueckii cultured with peanut oil cake as the carbon source yielded 5.35 mg ml(-1) of biosurfactant production. Five sets of microcosm biodegradation experiments were carried out with crude oil as follows: set 1 - bacterial cells+crude oil, set 2 - bacterial cells+crude oil+fertilizer, set 3 - bacterial cells+crude oil+biosurfactant, set 4 - bacterial cells+crude oil+biosurfactant+fertilizer, set 5 - with no bacterial cells, fertilizer and biosurfactant (control). Maximum degradation of crude oil was observed in set 4 (75%). Interestingly, when biosurfactant and bacterial cells were used (set 3), significant oil biodegradation activity occurred and the difference between this treatment and that in set 4 was 7% higher degradation level in microcosm experiments. It is evident from the results that biosurfactants alone is capable of promoting biodegradation to a large extent without added fertilizers.     

Extraction,Purification and Characterization of Thermostable,Alkaline Tolerant α-Amylase from <Emphasis Type="Italic">Bacillus cereus</Emphasis>

Thermostable alkaline α-amylase producing bacterium Bacillus cereus 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.     

A novel thermostable and halostable carboxymethylcellulase from marine bacterium <Emphasis Type="Italic">Bacillus licheniformis</Emphasis>AU01

A novel thermostable, halostable carboxymethylcellulase (CMCase) from a marine bacterium Bacillus licheniformisAU01 was purified 10.4-fold with 18% yield with a specific activity of 88.43 U/mg and the molecular weight was estimated as 37 kDa. The enzyme was optimally active at pH 9–10 and temperature 50–60°C and it was most stable up to pH 12 and 20–30% of NaCl concentration. The enzyme activity was reduced when treated with Hg²⁺, Fe²⁺ and EDTA and stimulated by Co²⁺, Mn²⁺, Mg²⁺ and Ca²⁺. Various cationic, anionic detergents and commercial detergents were not much affected CMCase activity.