Superparamagnetic iron oxide nanoparticles (SPION) with size ranging 10.6–37.8 nm were synthesized and characterized through XRD, FT-IR spectra, simultaneous TG-DTG-DTA, vibrational sample ...magnetometry (VSM) and transmission electron microscopy (TEM). Effect of SPION size variants on the growth-profile of Low-Density Polyethylene (LDPE) degrading microbial consortium consisting of
Microbacterium sp.,
Pseudomonas putida and
Bacterium Te68R was monitored in Minimal broth Davis medium lacking iron and dextrose. Besides accelerating the bacterial growth, these nanoparticles also improved the exponential phase durability by 36 h. Further, shifting in lag-phase and the additive effect of sonication was also documented on growth profiling. SPION of size 10.6 nm were selected and were found to significantly increase the biodegradation efficiency of consortium as revealed by λ-max shifts, Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA). The study highlights the significance of bacteria–nanoparticle interactions which can dramatically influence key metabolic processes like biodegradation.
The bioethanol production from lignocellulosic biomass has attracted wide interest globally in last decade. One of the main reasons for the high cost of bioethanol production from lignocellulosic ...biomass is the expensive enzymes involved in enzymatic hydrolysis of cellulose (cellulase). The utilization of agro-industrial waste as a potential substrate for producing enzymes may serve a dual purpose of reducing the environmental pollution along with producing a high value commercial product. Twelve different agro-industrial wastes were evaluated for extracellular cellobiose or β-glucosidase production by a mutant of Bacillus subtilis on solid state fermentations (SSF). The Citrus sinensis peel waste was found to be the most suitable substrate with highest BGL titre (35 U/gds). Optimum incubation time, inoculum size, moisture content and volume of buffer for enzyme extraction were 72 h, 40 % v/w, 10 mL and 20 mL respectively.
Issue Title: Application of Biotechnology for Biofuels The extracellular beta-glucosidase from microorganisms is generally produced in low levels. Therefore, in this study, a beta-glucosidase ...hyperproducing mutant was developed by multiple exposures of ethyl methyl sulfonate (EMS) and ultraviolet (UV) radiation (both individually and jointly) to Bacillus subtilis strain (PS). The developed mutants were screened, selected and characterized. The mutant, PS-UM1 developed after UV exposure alone, indicated a small increase in beta-glucosidase production (718 U/l) in comparison to the wild-type strain, PS (675 U/l). The mutant, PS-CM5 developed after EMS exposure alone, displayed a slightly better production (762 U/l) than both the above strains. However, after exposure of the wild-type strain to both UV and EMS mutagens jointly, a better mutant (PS-CM5-UM3) was developed with 1.2-fold increase in production (806 U/l). Further, optimization of culture conditions by classical "one-variable-at-a-time" approach was done to determine the optimum, pH, temperature and nitrogen sources. The selected mutant (PS-CM5-UM3) produced up to 1,797 U/l enzyme and was found to be stable for ten generations. The beta-glucosidase from the selected mutant (PS-CM5-UM3) was concentrated and purified using ammonium sulfate, dialysis and size-exclusion chromatography. The enzyme displayed maximal activity at 60 °C and it was found to be fairly stable at temperatures up to 70 °C for 30 min. Its molecular weight was determined to be around 60 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
A total of six bacterial isolates were developed into two consortia and tested for utilization of epoxy silicone blends (ESBs; % w/w: 3.0) and epoxy as the sole carbon source.
In-vitro biodegradation ...studies in minimal broth revealed that higher biomass and more sustained growth of consortia were obtained in the presence of epoxy and/or ESBs when these were incubated under aerobic conditions for 15 days. Treated samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric–differential thermogravimetry–differential thermal analysis (TG–DTG–DTA), which indicated the breakage and formation of bonds in the polymer backbone. Moreover, a weight loss of 34.17 and 36.9% was found in epoxy and ESBs, respectively after 15 days of treatment with consortium-1. Further,
in-vitro growth statistics study revealed more CFU count at mid-logarithmic phase in the presence of epoxy/ESBs unlikely to the absence of the polymers. However, the generation time was not affected. In the present study, consortium-1, comprising of
Microbacterium sp.,
Pseudomonas putida and
Bacterium Te 68R showed better biodegradation in comparison to consortium-2, wherein,
P. putida and
Pseudomonas aeruginosa were present. Overall, these results suggest that epoxy/ESBs polymers could be degraded by a biologically mediated process if a suitable consortium is used.
Second-generation bioethanol production by a newly isolated thermotolerant yeast strain was studied at 42 °C and above using pilot-scale dilute acid pretreated wheat straw (WS) as feedstock. This ...strain was identified as
Kluyveromyces marxianus
DBTIOC-35 by biochemical characterization as well as molecular phylogenetic analysis of the ITS-5.8S rRNA gene and D1/D2 domain of the 26S rRNA gene after PCR amplification and sequencing. Simultaneous saccharification and fermentation (SSF) at 42 °C and 45 °C using 10% biomass loading resulted in ethanol titers of 29.0 and 16.1 g L
−1
, respectively. At 42 °C ethanol productivity was higher during SSF (0.92 g L
−1
h
−1
) than separate hydrolysis and fermentation (SHF) (0.49 g L
−1
h
−1
) at 20% biomass loading. The results indicated that at 20% biomass loading, SSF without pre-saccharification led to more ethanol production (66.2 g L
−1
with 83.3% yield) at a faster rate than SSF with pre-saccharification (PSSF) which produced an ethanol titer of 61.8 g L
−1
, 77.7% yield and productivity of 0.86 g L
−1
h
−1
. Based on these findings, application of newly isolated yeast
K. marxianus
DBTIOC-35 in SSF of lignocellulosic biomass can eliminate the pre-saccharification step which is a novel advantage of thermotolerant yeasts in terms of cutting down the overall biomass to bioethanol process time and enhancing bioethanol titer, yields and productivities.
Application of thermotolerant yeast
Kluyveromyces marxianus
DBTIOC-35 in SSF decreases overall process time, and increases productivity and yield by allowing elimination of presaccharification step and use of high biomass concentration, respectively.
A variety of bacterial strains were isolated from waste
disposal sites of Uttaranchal, India, and some from
artificially developed soil beds containing maleic anhydride,
glucose, and small pieces of ...polyethylene. Primary screening
of isolates was done based on their ability to utilize highand
low-density polyethylenes (HDPE/LDPE) as a primary
carbon source. Thereafter, a consortium was developed
using potential strains. Furthermore, a biodegradation assay
was carried out in 500-ml flasks containing minimal broth
(250 ml) and HDPE/LDPE at 5 mg/ml concentration. After
incubation for two weeks, degraded samples were recovered
through filtration and subsequent evaporation. Fourier
transform infrared spectroscopy (FTIR) and simultaneous
thermogravimetric-differential thermogravimetry-differential
thermal analysis (TG-DTG-DTA) were used to analyze
these samples. Results showed that consortium-treated
HDPE (considered to be more inert relative to LDPE) was
degraded to a greater extent (22.41% weight loss) in
comparison with LDPE (21.70% weight loss), whereas, in
the case of untreated samples, weight loss was more for
LDPE than HDPE (4.5% and 2.5%, respectively) at 400oC.
Therefore, this study suggests that polyethylene could be
degraded by utilizing microbial consortia in an eco-friendly
manner. KCI Citation Count: 3
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