Cell growth and ?-amylase production characteristics ofBacillus amyloliquefaciens

Sequential and consolidated bioprocessing of biogenic municipal solid waste: A strategic pairing of thermophilic anaerobe and mesophilic microaerobe for ethanol production

Feedstock availability and its pretreatment, high process economics and insufficient ethanol (H_Et) titres necessitated the bioprocesses that are sustainable. The advanced consolidated bioprocessing (CBP_Seq) strategy presently considered for improved H_Et production involves, sequential coupling of CBP thermophile, Clostridium thermocellum ATCC-27405 with mesophilic microaerobe, Pichia stipitis NCIM-3498. Biogenic municipal solid waste (BMSW) pretreated with 0.5% NaOH (CS_PBMSW) served as the sole carbon source. CBP_Seq (23.99 g/L) fared better than CBP standalone (18.10 g/L) wherein 1.32-folds improvement in H_Et titre was recorded. Considering insufficient xylanase titre in cellulosome complex of C. thermocellum, CBP_Seq was performed employing exogenous xylanases (CBP_SeqE) to improve xylan digestibility and H_Et yield. CBP_SeqE-II biosystem at pH 5 showed maximum H_Et titre of 36.90 g/L which corresponds to yield of 0.26 g H_Et/ g CS_PBMSW. This study substantiates efficacy of CBP_SeqE-II biosystem in sustainable bioethanol production from BMSW in a single reactor without laborious steps.

Single pot bioprocessing for ethanol production from biogenic municipal solid waste

Burgeoning global energy demand and rapid diminution of fossil fuel reserves urged to seek for a sustainable energy source like bioethanol. Single pot bioprocessing (SPB) strategy employing in-house laccase, cellulase plus xylanase and amylase along with hexose and pentose sugar fermenting yeasts (Saccharomyces cerevisiae and Pichia stipitis) is designed in this study for ethanol production from biogenic municipal solid waste (BMSW). BMSW when subjected to simultaneous pretreatment and saccharification (SPS) resulted in 79.69% enzymatic digestibility and fared better compared to alkali pretreated counterparts (14.03%-51.10%). The maximum total sugar release in case of SPS was 146.9 g/L in 24 h. The maximum ethanol concentration of 5.24% (v/v) in 30 h was obtained from SPB of BMSW at 25% (w/v) solid loading. SPB for ethanol production from BMSW is an interesting and effective alternative to MSW going to landfill or incineration with an added perk of waste to wealth conversion.

Phosphate solubilization and acid phosphatase activity of Serratia sp. isolated from mangrove soil of Mahanadi river delta, Odisha, India

Phosphorus is an essential element for all life forms. Phosphate solubilizing bacteria are capable of converting phosphate into a bioavailable form through solubilization and mineralization processes. Hence in the present study a phosphate solubilizing bacterium, PSB-37, was isolated from mangrove soil of the Mahanadi river delta using NBRIP-agar and NBRIP-BPB broth containing tricalcium phosphate as the phosphate source. Based on phenotypic and molecular characterization, the strain was identified as Serratia sp. The maximum phosphate solubilizing activity of the strain was determined to be 44.84 μg/ml, accompanied by a decrease in pH of the growth medium from 7.0 to 3.15. During phosphate solubilization, various organic acids, such as malic acid (237 mg/l), lactic acid (599.5 mg/l) and acetic acid (5.0 mg/l) were also detected in the broth culture through HPLC analysis. Acid phosphatase activity was determined by performing p-nitrophenyl phosphate assay (pNPP) of the bacterial broth culture. Optimum acid phosphatase activity was observed at 48 h of incubation (76.808 U/ml), temperature of 45 °C (77.87 U/ml), an agitation rate of 100 rpm (80.40 U/ml), pH 5.0 (80.66 U/ml) and with glucose as a original carbon source (80.6 U/ml) and ammonium sulphate as a original nitrogen source (80.92 U/ml). Characterization of the partially purified acid phosphatase showed maximum activity at pH 5.0 (85.6 U/ml), temperature of 45 °C (97.87 U/ml) and substrate concentration of 2.5 mg/ml (92.7 U/ml). Hence the present phosphate solubilizing and acid phosphatase production activity of the bacterium may have probable use for future industrial, agricultural and biotechnological application.

Substrate dependent in vitro antifungal activity of Bacillus sp strain AR2

Background

Biosurfactants are a structurally diverse group of secondary metabolites with lots of potential to serve mankind. Depending upon the structure and composition they may exhibit properties that make them suitable for a particular application. Structural and compositional diversity of biosurfactant is unambiguously substrate dependent. The present study investigates the qualitative and quantitative effect of different water soluble carbon source on the biosurfactant produced by Bacillus amylofaciens strain AR2.

Results

Strain AR2 produced lipopeptide type biosurfactant while growing on water soluble carbon sources. Maximum biosurfactant production was observed in the sucrose supplemented minimal salt medium (MSM). Strain AR2 exhibited carbon source dependent surface tension reduction in the range of 30-37 mN/m, critical micelle concentration (CMC) in the range 80-110 mg/l and emulsification index (EI₂₄ kerosene) in the range of 32-66%. In dextrose, sucrose and glycerol supplemented MSM, strain AR2 produced lipopeptides as a mixture of surfactin, iturin and fengycin. However, in the presence of maltose, lactose and sorbitol only iturin was produced. This substrate dependent compositional variation in the lipopeptides significantly influenced antifungal activity. Lipopeptides produced by strain AR2 while growing on sucrose and dextrose based MSM was observed to be most efficient as an antifungal agent.

Conclusions

These results suggest that carbon source provided for the growth and biosurfactant production not only influences the yield but also the type of biosurfactant. Sucrose is the most suitable carbon source for production of lipopeptide biosurfactant with antifungal activity.

Optimization of physical factors affecting the production of thermo-stable organic solvent-tolerant protease from a newly isolated halo tolerant Bacillus subtilis strain Rand

Background

Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus Bacillus are active producers of extra-cellular proteases, and the thermostability of enzyme production by Bacillus species has been well-studied by a number of researchers. In the present study, the Bacillus subtilis strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia.

Results

A thermostable organic solvent-tolerant protease producer had been identified as Bacillus subtilis strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v) of (AB₆₀₀ = 0.5) inoculum size, in a culture medium (pH 7.0) and incubated for 24 h at 37°C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg). The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60°C, respectively.

Conclusion

Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic solvent. This unique property makes it attractive and useful to be used in industrial applications.

Production and partial characterization of thermostable and calcium-independent alpha-amylase of an extreme thermophile Bacillus thermooleovorans NP54

AIM

An investigation was carried out on the production of alpha-amylase by Bacillus thermooleovorans NP54, its partial purification and characterization.

METHODS AND RESULTS

The thermophilic bacterium was grown in shake flasks and a laboratory fermenter containing 2% soluble starch, 0.3% tryptone, 0.3% yeast extract and 0.1% K2HPO4 at 70 degrees C and pH 7.0, agitated at 200 rev min(-1) with 6-h-old inoculum (2% v/v) for 12 h. When the enzyme was partially purified using acetone (80%[v/v] saturation), a 43.7% recovery of enzyme with 6.2-fold purification was recorded. The KM and Vmax (soluble starch) values were 0.83 mg ml(-1) and 250 micromol mg(-1) protein min(-1), respectively. The enzyme was optimally active at 100 degrees C and pH 8.0 with a half-life of 3 h at 100 degrees C. Both alpha-amylase activity and production were Ca2+ independent.

CONCLUSIONS

Bacillus thermooleovorans NP54 produced calcium-independent and thermostable alpha-amylase.

SIGNIFICANCE AND IMPACT OF THE STUDY

The calcium-independent and thermostable alpha-amylase of B. thermooleovorans NP54 will be extremely useful in starch saccharification since the alpha-amylases used in the starch industry are calcium dependent. The use of this enzyme in starch hydrolysis eliminates the use of calcium in starch liquefaction and subsequent removal by ion exchange.

Production of a-amylase in acid cheese whey culture media with automatic pH control

The influence of aeration and automatic pH control on the production of <FONT FACE="Symbol">a</FONT>-amylase by a strain of Bacillus subtilis NRRL 3411 from acid cheese whey was studied. Tests were carried out in a rotary shaker and in mechanically stirred fermenters. <FONT FACE="Symbol">a</FONT>-amylase was analysed according to DUN’s method. Oxygen absorption rate was determined by Cooper’s method. Cell oxygen demand was determined as oxygen consumption in a Warburg respirometer. The level of dissolved oxygen was measured by means of a galvanic silver-lead electrode. Results suggest the possibility of industrial use of acid cheese whey as a carbon source for <FONT FACE="Symbol">a</FONT>-amylase production, since the yield was similar to that produced with lactose. The highest <FONT FACE="Symbol">a</FONT>-amylase levels 10,000 DUN/ml units were not attained at higher aeration rates -431 mLO2/L.h-. The indicated value correspond to a 96 h process with automatic pH control at 7.5. These conditions resulted in double concentration of <FONT FACE="Symbol">a</FONT>-amylase. The enzyme production was directly related to growth in the form of cell aggregates.