•The applicability of xylitol in food production processes and the pharmaceutical industry.•Agro-industrial wastes for the biotechnological production of xylitol.•Interferences encountered in the ...hydrolysis from lignocellulosic materials and treatments.•Microorganisms and operational conditions used for xylitol production.•Downstream processes to obtain crystals of xylitol.
Several studies have sought to evaluate alternative routes for the production of xylitol, a polyol with high employability in both the food and pharmaceutical industries. Large-scale production is typically achieved by a chemical process of d-xylose hydrogenation. However, due to the conditions employed in this procedure, it remains very costly. The biotechnological route has been the subject of intense research throughout the last decade because, apart from implying lower costs, many microorganisms can be used. The employment of unconventional substrates as carbon sources for this production also stands out as a very promising alternative. In addition to the possibility of being assimilated by many microorganisms, it becomes a good destination for the disposal of industrial waste. Thus, the aim of this review was to gather data on the biotechnological production of xylitol from agro-industrial waste, as well as to identify the best cultivation conditions (i.e. treatment of hydrolysate, pH, temperature and aeration) employed in the process.
Xylitol was biotechnologically produced by
Kluyveromyces marxianus
ATCC36907 using the hemicellulosic hydrolysate of the cashew apple bagasse (CABHH). Sequentially, the present study investigated the ...recovery and purification of xylitol evaluating different antisolvents ethanol, isopropanol and the ionic liquid 2-hydroxyl-ethylammonium acetate (2-HEAA), their proportion in the medium (10–90% v/v), and their cooling rate (
V
C
0.25–0.50 °C/min). These processes were contrasted with the crystallization process of commercial xylitol. This study is the first to assess xylitol crystallization using a protic ionic liquid. The hydrolysate obtained from a mild treatment with sulfuric acid contained mainly glucose and xylose at concentrations of 15.7 g/L and 11.9 g/L, respectively. With this bioprocess, a maximum xylitol production of 4.5 g/L was achieved. The performance of the investigated antisolvents was similar in all conditions evaluated in the crystallization process of the commercial xylitol, with no significant difference in yields. For the crystallization processes of the produced xylitol, the best conditions were: 50% (v/v) isopropanol as antisolvent, cooling rate of 0.5 °C/min, with a secondary nucleation of yield and purity of 69.7% and 84.8%, respectively. Under the same linear cooling rate, using ethanol, isopropanol or the protic ionic liquid 2-hydroxyl-ethylammonium acetate (2-HEAA), crystallization did not occur, probably due to the presence of carbohydrates not metabolized by the yeast in the broth, which influences the solubility curve of xylitol. With the results of this work, a possible economical and environmentally friendly process of recovery and purification of xylitol from CABHH could be proposed.
Oil spills in marine environments are common due to the intense flow of transport. One of the ways to reduce the effects caused by these spills is bioremediation. A biosurfactant produced by ...Acinetobacter venetianus AMO1502, a strain isolated from oil spilled off the Brazilian coast, was investigated as a bioremediation agent. The highest cell growth and biosurfactant production were obtained using a culture medium supplemented with NaCl. The biosurfactant had high emulsifying activity and reduced the surface tension of water by up to 41.7 %. This biomolecule showed high stability related to temperature, pH, and NaCl addition as petroderivate removal agent, reaching 25 % removal of the engine oil in sand and 12 % removal of the oil in an aqueous medium, also reducing oil stains adsorbed on contaminated stones.
Acinetobacter venetianus isolated from samples of oil spilled on the Brazilian coast was able to produce a biosurfactant with high emulsification potential and stability against variations in temperature, pH, and presence of NaCl. The bioproduct obtained was capable to disperse oil residues present in stones contaminated by oil spills, evidencing its potential for bioremediation.
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•The enzyme β-galactosidase could be adsorbed on MANAE support at pH 5–9.•Activity was almost fully preserved.•The enzyme remained immobilized at 25mM of buffers.•The stability ...strongly depended on the immobilization pH value.•Under certain conditions, some preparations were more stable than free enzyme.
β-Galactosidase from Aspergillus oryzae has been immobilized at pH 5, 7 and 9 on an aminated support using 5mM buffer. The immobilization was total in 30min, maintaining 75–80% of activity. These preparations were inactivated at different pH values and in the presence of 50% ethanol. The stability of the enzyme immobilized at pH 9 was much lower than that of the enzyme immobilized at pH 5 under all studied conditions but the differences decreased as the ionic strength of the inactivation solution increased. The likeliest explanation to these different stabilities depending on the immobilization pH was that the enzyme presented a different orientation on the support. The enzyme immobilized at pH 5 was more stable than the free enzyme at pHs 5 and 9 (by a 2 or a 6 fold factor respectively), while at pH 7 the free enzyme was clearly more stable than the immobilized enzyme.
β-Galactosidase was produced by the yeast
Kluyveromyces lactis
NRRL Y1564 in cheese whey supplemented with yeast extract under the optimal temperature of 30 °C, delivering an enzymatic activity of ...4418.37 U/g
cell
after 12 h of process. In order to develop more stable biocatalysts, the enzyme produced by fermentation was immobilized on 2.0% w/v chitosan activated with glutaraldehyde, epichlorohydrin or glycidol, producing a highly active and stable biocatalyst capable of hydrolyzing lactose and producing lactulose simultaneously. The biocatalyst obtained by immobilization in chitosan-glutaraldehyde showed high storage stabilities (100% of its activity when stored at 4 °C 105 days). Regarding the milk lactose hydrolysis by both the soluble and the immobilized enzyme, the conversions obtained were 38.0% and 42.8%, respectively. In this study, by using a biocatalyst deriving from enzyme immobilization to chitosan support, a lactulose production of 17.32 g/L was also possible.
Different strategies for simultaneous saccharification and fermentation (SSF) process were developed to enhance the productivity of ethanol by
Kluyveromyces marxianus
ATCC36907 as a part of ...biorefinery concept using cashew apple bagasse (CAB) as biomass. CAB was pretreated with 4.3% (v/v) alkaline hydrogen peroxide at pH 11.5 (CAB-AHP). Batch SSF conducted at 45 °C using 10% (w/v) CAB-AHP reported the highest concentration and ethanol yield. In the fed-batch SSF, the highest production (7.91 g ethanol/100g
CAB
) and ethanol yield (84.69%) were achieved using 10% (w/v) CAB-AHP initial solids load, 4% solid feeding at 24 h, and the feeding of enzymes only in the beginning of the process. The recycling of pretreatment inputs decreased 50% of the batch-SSF efficiencies, saving the consumption of water, H
2
O
2
, and NaOH in 66.67%, 48.44%, and 66.67%, respectively. Lignin was extracted from the hydrolysate with yield of 39.2%. Thus, the proposed biorefinery concept utilizes CAB to produce ethanol with high efficiency by fed-batch SSF, pretreatment input recycling, and the utilization of the extracted lignin for future applications.
The present study evaluated the use of a pressurized method to extract phycobiliproteins from the cyanobacterium
Arthrospira platensis
using sodium phosphate buffer as an extracting solution. ...Phycobiliprotein extracts were characterized and their antioxidant and anticancer activities (on different cancer cell lines) were determined. A high extraction yield was obtained when high pressure was used, without any alteration of the molecules’ biofunctionality. Maximum phycocyanin and allophycocyanin concentrations obtained (at 100 bar after 360 min) were 4.44 g L
−1
and 1.63 g L
−1
, respectively. The purity indexes of extract were 3.59 (A
615
/A
280
) for phycocyanin and 1.72 (A
652
/A
280
) for allophycocyanin. The purified phycobiliprotein extract showed high antioxidant activity, with 98% in the reduction of 2,2-diphenyl-1-picryl-hydrazil (DPPH) radicals and 100% in the chelation of ferrous ions, and it presented in vitro anticancer activity for HL60 leukemic cells.
This study's aim was to determine the presence, as well as to evaluate the health and environmental impacts, of chemical elements from firearm shots during shooter practice at outdoor shooting ...ranges, both in the environment and on the shooters' hands. Two high-precision devices were used for measuring suspended particles that are released during discharge of Taurus PT 100 .40 caliber pistols. The analysis of collected data allowed the identification of specific distribution patterns of samples that were adsorbed. Moreover, samples were collected from the opisthenar area of the hand to investigate both the occurrence and deposition of particles and chemical elements through scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The results indicate that copper, lead, and zinc concentration profiles will be able to delimit and reveal more precise details regarding shots made with nontoxic ammunition (NTA). In particular, the residual graphic analysis indicated that the majority of metal deposited in the shooter's hand is zinc. Further, the metals barium and lead also were detected. Due to the exposure to these elements, it could be concluded that engineering controls and administrative management should be sought in order to avoid human overexposure and environmental release of these airborne toxic metals.
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•Screening played important role to obtain biosurfactant-producing strains.•Renewable substrate was successfully used for biosurfactant production.•The biosurfactant have had ...excellent emulsifying activity.•The structure of this biosurfactant was determined to be a cyclic lipopeptide.•Produced biosurfactant have potential application in remediation of oil contaminated soil.
The ability of some microorganisms to use clarified cashew apple juice as carbon and energy source for biosurfactant production was assessed under strict controlled conditions. Twelve strains of Bacillus were isolated and evaluated regarding their biosurfactant production capabilities. The biosurfactant obtained with these selected strains showed the capacity of decreasing the surface tension of water from 72.0 to 31.8 mN.m−1 and the interfacial tension of n-hexadecane to 27.2 mN.m−1, with a critical micelle concentration of 12.5 mg.L−1. Not only did the biosurfactant present excellent stability to pH, temperature and salinity, it also showed emulsifying properties in different hydrocarbons. The behavior of the phase diagrams showed the potential of the produced biosurfactant to obtain relatively-stable emulsions for up to 96 h, which allows for its application in several areas. The semi-purified biosurfactant did not show toxicity against Lactuca sativa (lettuce) or Artemia salina (microcrustacean), presenting an LC50 of 612.27 μ mL-1. The surfactant was characterized as being a cyclic lipopeptide with molecular structure similar to that of surfactin. Furthermore, through the employment of the surfactant produced, the remediation effect in oil-contaminated soil could be significantly improved.
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant structures of the cashew able bagasse (CAB), lignocellulosic by-product in ...Brazil with no commercial value, is obtained from cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses, and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L
−1
of NaOH (372 ± 12 and 355 ± 37 mg g
glucan
−1
) when 2% (
w
/
v
) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step, improvement on solid percentage (16%
w
/
v
) and enzyme load (30 FPU g
CAB-M
−1
) increased glucose concentration to 15 g L
−1
. The fermentation of the hydrolyzate by
Saccharomyces cerevesiae
resulted in ethanol concentration and productivity of 5.6 g L
−1
and 1.41 g L
−1
h
−1
, respectively.
