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Development of the resistance is the major problem in cancer therapy. Docetaxel is a taxol alkaloid that is frequently used in metastatic breast cancer. However, resistance often limits the usefulness of this drug in many breast cancer patients. Manipulation of resistant cells to re-sensitize to the therapeutic effect of docetaxel is current strategy to overcome this problem. Here, we have introduced 'Iturin A' as a potent chemosensitizer in docetaxel resistant breast cancer cells. Combination of Iturin A and docetaxel treatment significantly hampered the proliferation of docetaxel resistant MDA-MB-231 and MDA-MB-468 breast cancer cells. Cell cycle analysis also showed massive amount of apoptotic population (Sub G0/G1) in combination therapy. A number of apoptotic and anti-apoptotic proteins were significantly altered in dual drug treated groups. Caspase 3 dependent cell death was observed in dual treatment. Molecular mechanism study showed that over-expression of Akt and its downstream signaling pathway was associated with docetaxel resistance. Iturin A significantly reduced Akt signaling pathway in resistant cells. This mechanistic action might be the reason behind the chemo-sensitization effect of Iturin A in docetaxel resistant breast cancer cells. In conclusion, Iturin A resensitized the resistant breast cancer cells to docetaxel therapy by inhibiting Akt activity.

Microbial biosurfactants produce foam during aerobic-fermentation processes. The degree of foaminess and foam stability of the lipopeptide-biosurfactant produced by a marine Bacillus megaterium strain were investigated using simulated biosurfactant solution (SBS), biosurfactant broth without cells (BBWOC) and biosurfactant broth with cells (BBWC) in bubble column experiments. The experimental data for foam collapse were fitted using a first-order foam decay model. The first-order rate constant (k), a measure of foam stability, was maximum (k=0.0003 S(-1)) for BBWOC in the pH range 6-9. However, maximum foam stability (k=0.0006 S(-1)) was restricted to pH 7 for BBWC. Foam-based metal removal studies revealed that the metal removal followed a saturation model. The relative binding capacity of each divalent metal was greatly affected by the presence of other divalent metals. The order of lipopeptide binding capacity of the metals was Fe(2+)>Ca(2+)>Mg(2+), with Fe(2+) significantly influencing the foam stability. In case of Fe(2+), Ca(2+) and Mg(2+), maximum metal recovery of 64.7±4.3%, 52±3.1% and 41.4±3.6% respectively was observed at pH 7. The enrichment (E) of the other media components, including cells, was comparatively insignificant. The results of this study have implications in designing and optimizing biosurfactant or protein recovery in situ by foam fractionation as an inexpensive strategy, and also in facilitated metal recovery from industrial effluents and ores., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Bacillus megaterium RB-05 was grown on glucose and on "tossa-daisee" (Corchorus olitorius)-derived jute, and production and composition of extracellular polysaccharide (EPS) were monitored. An EPS yield of 0.065 ± 0.013 and of 0.297 g ± 0.054 g(-1) substrate after 72 h was obtained for glucose and jute, respectively. EPS production in the presence of jute paralleled bacterial cellulase activity. High performance liquid chromatography (HPLC), matrix assisted LASER desorption/ionization-time of flight (MALDI-ToF) mass spectroscopy, and fourier transform infrared (FT-IR) spectroscopy demonstrated that the EPS synthesized in jute culture (JC) differed from that synthesized in glucose mineral salts medium (GMSM). While fucose was only a minor constituent (4.9 wt.%) of EPS from GMSM, it a major component (41.9 wt.%) of EPS synthesized in JC. This study establishes jute as an effective fermentation substrate for EPS production by a cellulase-producing bacterium., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The bioinspired synthesis of construction material, known as biocement, represents a significant advancement in addressing the environmental sustainability issues associated with traditional cement use in the built environment. Biocement is produced through the process of microbially induced bio-mineralization (MIBM), which offers a promising alternative or supplement to conventional cement, potentially reducing its consumption. Despite extensive literature on the application of biocement in construction biotechnology, the fundamental mechanisms underlying its ability to enhance concrete quality remain poorly understood. This study focuses on the kinetics of biomineral synthesis by two Bacillus species; Bacillus megaterium RB05 and Bacillus foraminis DRG5, to identify the most effective strain for biomineralization. Bioconcrete specimens were created by adding inoculum containing Bacillus megaterium RB05 cells with a nutrient solution to the concrete mixture in a layer-by-layer approach. After 28 days of water curing, nanoparticles of CaCO3, ranging in size from 27 to 82 nm, were produced in the bioconcrete specimens. The resulting concrete, containing nanocrystalline biogenic calcite, demonstrated significant improvements in mechanical properties. Specifically, compressive and tensile strengths of the bioconcrete, tested using a universal testing machine (UTM), increased by 7.69 ± 0.08% and 22 ± 0.1%, respectively, after 72 h of curing. Additionally, the biocement was found to exhibit an organic–inorganic hybrid nature, as identified by TEM, EDAX, FESEM, FTIR, and XRD analyses. The enhanced mechanical properties were attributed to the high surface-to-volume ratio and hybrid nature of the calcite nanoparticles. The findings of this investigation are encouraging, suggesting the potential development of future green and self-sustainable construction materials or bioconcrete. [ABSTRACT FROM AUTHOR]

Microbial lipopeptide synthesis is often associated with the co-production of more than one family of isoforms. The selective lipopeptide production is strongly influenced by the processing conditions and the limiting nutrient sources such as oxygen and nitrogen during a fermentation process. In the current study, comprehensive investigations carried out in shake flasks revealed that the oxygen-limiting conditions increased the selective fengycin production. The optimal conditions of shake flasks studies of 340 mL medium volume (in 1 L conical flask), 4.67% v/v inoculum volume and 121 rpm agitation speed resulted in a total lipopeptide concentration of 5.34 ± 0.1 g L −1 , with more selectivity toward fengycin of 74.1%. Among the three rational approaches investigated to recreate these optimal conditions in a 3.7 L stirred tank bioreactor, the strategy, submerged aeration followed by surface aeration effectively reproduced the optimal conditions of shaker flasks resulting in a total lipopeptide concentration of 4.94 ± 0.15 g L −1 , with fengycin selectivity of 71%. The present study thus offers a process design strategy of potential industrial significance to the challenge of selectively enhancing the target product, while marginalizing other closely related co-products. [ABSTRACT FROM AUTHOR]

Abstract: Extracellular polysaccharide production of Bacillus megaterium RB-05, a river sediment isolate, was optimized in glucose mineral salts medium by response surface methodology. Experimental maximum production (0.895gl−1) was very close to the theoretical maximum value of 0.904gl−1 after 25h incubation at 33.3°C and pH 7.62. The maximum specific growth rate and specific EPS production rate were calculated to be 0.65h−1 and 0.215gg−1 cell respectively. The growth yield coefficient and product yield coefficients were evaluated to be 0.13g of biomass g−1 glucose, 0.065g of EPS g−1 glucose, and 0.484g of EPS g−1 biomass. Yields were enhanced up to 1.2gl−1 with l-aspergine and d-biotin supplementation. EPS showed evidence of free radical scavenging in in vitro studies. [Copyright &y& Elsevier]

Abstract: Bacillus megaterium RB-05 was grown on glucose and on “tossa-daisee” (Corchorus olitorius)-derived jute, and production and composition of extracellular polysaccharide (EPS) were monitored. An EPS yield of 0.065±0.013 and of 0.297g±0.054g−1 substrate after 72h was obtained for glucose and jute, respectively. EPS production in the presence of jute paralleled bacterial cellulase activity. High performance liquid chromatography (HPLC), matrix assisted LASER desorption/ionization-time of flight (MALDI-ToF) mass spectroscopy, and fourier transform infrared (FT-IR) spectroscopy demonstrated that the EPS synthesized in jute culture (JC) differed from that synthesized in glucose mineral salts medium (GMSM). While fucose was only a minor constituent (4.9wt.%) of EPS from GMSM, it a major component (41.9wt.%) of EPS synthesized in JC. This study establishes jute as an effective fermentation substrate for EPS production by a cellulase-producing bacterium. [Copyright &y& Elsevier]

Abstract: Lignocellulosic fiber (jute), a low cost natural complex carbon source, was introduced in a fermentation medium to observe the effects of its constituents on the production of a commercially potent bacterial extracellular polysaccharide (EPS) synthesized by Bacillus megaterium RB-05. It has been found that among all the fiber components the bacterium has utilized cellulose most for the EPS production. Maximum polymer yield of 0.297gg−1 substrate was found after 72h fermentation. Consumption of fiber components was typically driven by in situ bacterial enzyme activity as EPS production was found significantly (p<0.05) accelerated from 36h onwards with considerable cellulase activity. Utilization of fiber components during different fermentation hours were characterized using scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, tensile property, and contact angle measurement. [Copyright &y& Elsevier]