Microbial induced calcite precipitation can consolidate martian and lunar regolith simulants.

We demonstrate that Microbial Induced Calcite Precipitation (MICP) can be utilized for creation of consolidates of Martian Simulant Soil (MSS) and Lunar Simulant Soil (LSS) in the form of a 'brick'. A urease producer bacterium, Sporosarcina pasteurii, was used to induce the MICP process for the both simulant soils. An admixture of guar gum as an organic polymer and NiCl2, as bio- catalyst to enhance urease activity, was introduced to increase the compressive strength of the biologically grown bricks. A casting method was utilized for a slurry consisting of the appropriate simulant soil and microbe; the slurry over a few days consolidated in the form of a 'brick' of the desired shape. In case of MSS, maximum strength of 3.3 MPa was obtained with 10mM NiCl2 and 1% guar gum supplementation whereas in case of LSS maximum strength of 5.65 Mpa was obtained with 1% guar gum supplementation and 10mM NiCl2. MICP mediated consolidation of the simulant soil was confirmed with field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and thermogravimetry (TG). Our work demonstrates a biological approach with an explicit casting method towards manufacturing of consolidated structures using extra-terrestrial regolith simulant; this is a promising route for in situ development of structural elements on the extra-terrestrial habitats.

Microbially induced calcite precipitation using Bacillus velezensis with guar gum.

Mineral precipitation via microbial activity is a well-known process with applications in various fields. This relevance of microbially induced calcite precipitation (MICP) has pushed researchers to explore various naturally occurring MICP capable bacterial strains. The present study was performed to explore the efficiency of microbially induced calcite precipitation (MICP) via locally isolated bacterial strains and role of guar gum, which is a naturally occurring polymer, on the MICP process. The strains were isolated from local soil and screened for urease activity Further, the urease positive strain was subjected to urea and calcium chloride based medium to investigate the efficacy of isolated strain for microbial induced precipitation. Among screened isolates, the soil bacterium that showed urease positive behaviour and precipitated calcium carbonate was subjected to 16S rRNA gene sequencing. This strain was identified as Bacillus velezensis. Guar gum-a natural polymer, was used as a sole carbon source to enhance the MICP process. It was observed that the isolated strain was able to breakdown the guar gum into simple sugars resulting in two-fold increase in calcium carbonate precipitate. Major bio-chemical activities of isolated strain pertaining to MICP such as ammonium ion concentration, pH profiling, and total reducing sugar with time were explored under four different concentrations of guar gum (0.25%, 0.5%, 0.75% and 1% w/v). Maximum ammonium ion concentration (17.5 µg/ml) and increased pH was observed with 1% guar gum supplementation, which confirms augmented MICP activity of the bacterial strain. Microstructural analysis of microbial precipitation was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, which confirmed the presence of calcium carbonate in different phases. Further, XRD and SEM based studies corroborated that guar gum supplemented media showed significant increase in stable calcite phase as compared to media without guar gum supplementation. Significant diverse group of nitrogenous compounds were observed in guar gum supplemented medium when subjected to Gas Chromatography-Mass spectrometry (GC-MS) profiling.

Partial purification and characterization of amylase enzyme under solid state fermentation from Monascus sanguineus.

Amylase is an important enzyme having a varied range of industrial applications from food to cosmetics, from pharmaceutical to detergent industry, etc. The present study was carried out considering these important applications of amylase enzyme. Monascus sanguineus also has not been explored for its efficiency to produce amylase enzymes under solid state fermentation. In the present study, various substrates were screened and among them beetroot as a solid substrate has given maximum yield (0.029 U/mL). Enzyme activity was further optimized by response surface methodology (RSM) and maximum experimental yield of 0.014 U/mL was obtained at optimized conditions of pH 5, incubation temperature of 50 °C and 10 min incubation time. A MATLAB software package was used for the graphical and regression analysis of the experimented data. Enzyme kinetics was calculated with different concentrations of starch and observed Km value was 0.055 mM from linear regression analysis. The enzyme was moderately inhibited (44.7%) by NaCl and KCl (0.105 U/mL) with minimum inhibition (14.8%) observed with SDS. Molecular weight calculation and amylase confirmation in protein sample was done by SDS-PAGE and Zymography. Calculated molecular weight was 56 kDa. Alkaline amylase produced by M. sanguineus has exhibited high efficiency towards removal of stains on cloths in combination with commercial detergent (Surf excel) at 20 °C. It can be concluded that the fungus M. sanguineus is a good source of amylase production under solid state fermentation. Application of amylase produced by M. sanguineus in detergent industry was also carried out and it was proven very effective in stain removal from the fabrics.

Statistical optimization of lovastatin and confirmation of nonexistence of citrinin under solid-state fermentation by Monascus sanguineus.

Lovastatin is a well-known natural statin, which is used for lowering plasma cholesterol levels by inhibiting 3-hydroxy-3-methyl glutaryl coenzyme A reductase. Different strains of Aspergillus and Monascus sp. have been exploited for statin production but Monascus sanguineus is still unexplored. In this study, lovastatin production from Monascus sanguineus under solid state fermentation was optimized using response surface methodology. The optimized value of the lovastatin yield was 20.04 mg/gds with soybean concentration of 20 g/L, CaCl2 concentration of 2.5 g/L, acetic acid concentration of 25 µL and inoculum size of 3.4 mL. This study also documented spectrometric characterization and fragment pattern of lovastatin with the help of Fourier transfer infrared spectrometry and mass spectrometry. Citrinin was not detected in any of the samples used for this study.

Bio-synthesis and screening of nutrients for lovastatin by Monascus sp. under solid-state fermentation.

In this study Monascus strains were screened for lovastatin production. These strains namely Monascus purpureus, Monascus sanguineus and their co-culture were able to produce lovastatin in solid state fermentation. Sensitivity of lovastatin was tested on Saccharomycess cerevaceae and Candida sp. where the former exhibited large zone of inhibition as compared to the latter. Presence of lovastatin was confirmed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Quantification of lovastatin was done with UV spectrometer at 238 nm. Further, Plackett-Burman methodology was applied for screening of nutrients for lovastatin production. Different substrates were screened and amongst them, wheat bran was found to be the best substrate for lovastatin synthesis. Seven nutrients were screened according to the Plackett-Burman design for lovastatin yield. MgSO4.7H2O showed the positive impact on lovastatin yield whereas lactose showed the maximum negative effect with M. purpureus. For M. sanguineus, CaCl2.2H2O displayed the dominant negative effect and soybean the significant positive. With co-culture, the effect of lactose was positive whereas that of malt extract was negative and dominant. The maximum lovastatin yield for M. sanguineus, M. purpureus and co-culture was estimated to be 0.402, 0.27 and 0.26 mg/g respectively.

Partial Purification and Characterization of β-glucosidase from Monascus sanguineus

The aim of the present work was to study the production and characterization of β-glucosidase from Monascus sanguineus. Agro-waste residues were screened to obtain the maximum yield of enzyme. Jack fruit seed was the best substrate for enzyme production. Studies on the optimization of pH and temperature showed acidic pH favorable for enzymatic activity, whereas the optimum temperature was 60°C. Enzyme kinetics studies with different concentration of pNPG showed the calculated value of Km approximately 0.89 mM with the non-linear regression and 0.98 mM with the linear regression techniques. The enzyme was predominantly inhibited by KCl (69.8%) and moderately inhibited by CaCl2 (14.8%). Studies on the sensitivity for glucose showed that after 100 mM concentration of glucose, inhibition in pNPG hydrolysis took place. The molecular weight of the protein was estimated as 116 and 66 kDa with SDS- PAGE and zymography was carried out to verify the specific activity.

Statistical optimization of pigment production by Monascus sanguineus under stress condition.

Natural pigments are produced by the Monascus sp., which are used for coloring food substances. The intent of this study was to optimize the pigment yield and biomass produced from the unexplored Monascus sanguineus in submerged culture under stress conditions. For inducing thermal stress, the spores were incubated at various temperatures at higher ranges. For inducing osmotic stress, varied concentrations of NaCl, glycerol, and peptone were used. The medium components were optimized by response surface methodology (RSM). The combined effects of the four medium constituents mentioned were studied using a 24 full factorial central composite design (CCD). The relationships between the predicted values and actual values, independent variable, and the response were calculated according to a second-order quadratic model. It was deduced that the variable with the leading effect was the linear effect of glycerol concentration. Furthermore, the quadratic effects of peptone and the interactive effects of temperature and glycerol were more noteworthy than other factors. The optimum values for the test variables in coded factors were found to be spores treated with 70°C for temperature, 0.25 M for glycerol, 0.51% (w/v) for peptone, and 1.25% (w/v) for NaCl, corresponding to a maximum red pigment yield of 55.67 color value units (CVU)/mL. With optimized conditions, the pigment yield was almost three times the yield observed with the control.