Efficient production of GlcNAc in an aqueous-organic system with a Chitinolyticbacter meiyuanensis SYBC-H1 mutant.

OBJECTIVES: Shellfish waste is a primary source for making N-acetyl-D-glucosamine. Thus, establishing a high-efficiency and low-cost bioconversion method to produce N-acetyl-D-glucosamine directly from shellfish waste was promising. RESULTS: A mutant C81 was obtained from Chitinolyticbacter meiyuanensis SYBC-H1 via 60Co-γ irradiation. This mutant C81 showed the highest chitinase activity of 9.8 U/mL that was 85% higher than the parent strain. The mutant C81 exhibted improved antioxidant activities, including total antioxidant capacity, superoxide radical ability, and hydroxyl radical scavenging ability, compared to that of the parent strain. Four out of nine organic solvents increased the chitinase activity by 1.9%, 6.8%, 11.7%, and 15.8%, corresponding to methylbenzene, n-heptane, petroleum ether, and n-hexane, respectively. The biphase system composed of aqueous and hexane presented a five-fold reduction of cell viability compared to the control. Using a continuous fermentation bioconversion process, 4.2 g/L GlcNAc was produced from crayfish shell powder with a yield of 80% of the chitin content. CONCLUSIONS: This study demonstrated that the mutant C81 is suitable for converting crayfish shell powder into GlcNAc in an aqueous-organic system.

Study on the biodegradation characteristics and mechanism of tetracycline by Serratia entomophila TC-1.

Microbial degradation is an important solution for antibiotic pollution in livestock and poultry farming wastes. This study reports the isolation and identification of the novel bacterial strain Serratia entomophila TC-1, which can degrade 87.8 % of 200 mg/L tetracycline (TC) at 35 °C, pH 6.0, and an inoculation amount of 1 % (v/v). Based on the intermediate products, a possible biological transformation pathway was proposed, including dehydration, oxidation ring opening, decarbonylation, and deamination. Using Escherichia coli and Bacillus subtilis as biological indicators, TC degraded metabolites have shown low toxicity. Whole-genome sequencing showed that the TC-1 strain contained tet (d) and tet (34), which resist TC through multiple mechanisms. In addition, upon TC exposure, TC-1 participated in catalytic and energy supply activities by regulating gene expression, thereby playing a role in TC detoxification. We found that TC-1 showed less interference with changes in the bacterial community in swine wastewater. Thus, TC-1 provided new insights into the mechanisms responsible for TC biodegradation and can be used for TC pollution treatment.

Evaluation of a data-driven intelligent waste classification system for scientific management of garbage recycling in a Chinese community.

Waste classification management is effective in addressing the increasing waste output and continuous deterioration of environmental conditions. The waste classification behaviour of resident is an important basis for managers to collect and allocate resources. Traditional analysis methods, such as questionnaire, have limitations considering the complexity of individual behaviour. An intelligent waste classification system (IWCS) was applied and studied in a community for 1 year. Time-based data analysis framework was constructed to describe the residents' waste sorting behaviour and evaluate the IWCS. The results showed that residents preferred to use face recognition than other modes of identification. The ratio of waste delivery frequency was 18.34% in the morning and 81.66% in the evening, respectively. The optimal time windows of disposing wastes were from 6:55 to 9:05 in the morning and from 18:05 to 20:55 in the evening which can avoid crowding. The percentage of accuracy of waste disposal increased gradually in a year. The amount of waste disposal was largest on every Sunday. The average accuracy was more than 94% based on monthly data, but the number of participating residents decreased gradually. Therefore, the study demonstrates that IWCS is a potential platform for increasing the accuracy and efficiency of waste disposal and can promote regulations implementation.

A dual bacterial alliance removed erythromycin residues by immobilizing on activated carbon.

Removing erythromycin from the environment is a major challenge. In this study, a dual microbial consortium (Delftia acidovorans ERY-6A and Chryseobacterium indologenes ERY-6B) capable of degrading erythromycin was isolated, and the erythromycin biodegradation products were studied. Coconut shell activated carbon was modified and its adsorption characteristics and erythromycin removal efficiency of the immobilized cells were studied. It was indicated that alkali-modified and water-modified coconut shell activated carbon and the dual bacterial system had excellent erythromycin removal ability. The dual bacterial system follows a new biodegradation pathway to degrade erythromycin. The immobilized cells removed 95% of erythromycin at a concentration of 100 mg L-1 within 24 h through pore adsorption, surface complexation, hydrogen bonding, and biodegradation. This study provides a new erythromycin removal agent and for the first time describes the genomic information of erythromycin-degrading bacteria, providing new clues regarding bacterial cooperation and efficient erythromycin removal.

Construction and application of highly efficient waste cooking oil degrading bacteria consortium in oily wastewater.

The treatment of cooking oil wastewater is an urgent issue need to be solved. We aimed to screen for efficient oil-degrading bacteria and develop a new microbial agent for degrading waste cooking oil in oily wastewater. Three extremely effective oil-degrading bacteria, known as YZQ-1, YZQ-3, and YZQ-4, were found by the enrichment and acclimation of samples from various sources and separation using oil degradation plates. The 16S rRNA sequencing analysis and phylogenetic tree construction showed that the three strains were Bacillus tropicus, Pseudomonas multiresinivorans, and Raoultella terrigena. Under optimal degradation conditions, the maximal degradation rates were 67.30 ± 3.69%, 89.65 ± 1.08%, and 79.60 ± 5.30%, respectively, for YZQ-1, YZQ-3, and YZQ-4. Lipase activity was highest for YZQ-3, reaching 94.82 ± 12.89 U/L. The best bacterial alliance was obtained by adding equal numbers of microbial cells from the three strains. Moreover, when this bacterial alliance was applied to oily wastewater, the degradation rate of waste cooking oil was 61.13 ± 7.30% (3.67% ± 2.13% in the control group), and COD removal was 62.4% ± 5.65% (55.60% ± 0.71% in the control group) in 72 h. Microbial community analysis results showed YZQ-1 and YZQ-3 were adaptable to wastewater and could coexist with local bacteria, whereas YZQ-4 could not survive in wastewater. Therefore, the combination of YZQ-1 and YZQ-3 can efficiently degrade oil and shows great potential for oily wastewater treatment.

Efficient degradation of tylosin by Klebsiella oxytoca TYL-T1.

Tylosin is widely used in livestock; however, the release of tylosin through animal manure can cause serious environmental problems. In this study, a new tylosin-degrading strain, TYL-T1, was isolated. Its phylogenetic similarity to Klebsiella oxytoca was found to be 99.17 %. TYL-T1 maintained good growth at 40 °C over a broad pH range (4.0-10). TYL-T1 degraded 99.34 % of tylosin in 36 h under optimal conditions (tylosin initial concentration: 25 mg/L, pH: 7.0, and temperature: 35 °C). After LC-MS-MS analysis, a new degradation pathway for tylosin was proposed, including ester bond breaking of the macrolide lactone ring, redox reaction, and loss of mycinose and mycarose. Based on a transcriptome analysis, 164 genes essential for degradation were upregulated through hydrolysis and redox of tylosin. Among various transferases, lipopolysaccharide methyltransferase, glycogen glucosyltransferase, and fructotransferase were responsible for tylosin degradation. The present study revealed the degradation mechanism of tylosin and highlighted the potential of Klebsiella oxytoca TYL-T1 to remove tylosin from the environment.

Biodegradation of tylosin in swine wastewater by Providencia stuartii TYL-Y13: Performance, pathway, genetic background, and risk assessment.

Microbial bioremediation offers a solution to the problem of residual antibiotics in wastewater associated with animal farms. Efficient degradation of antibiotic residues depends upon the genetic make-up of microbial degraders, which requires a comprehensive understanding of the degradation mechanisms. In this study, a novel, efficient tylosin (TYL)-degrading bacterium, Providencia stuartii TYL-Y13 (Y13) was isolated, which could completely degrade 100 mg/L TYL within 15 h under optimal operating conditions at 40 â„ƒ, pH 7.0 %, and 1 % (v/v) bacterial inoculation rate. Whole genome sequencing revealed that strain Y13 consists of a circular chromosome and two plasmids. A new biodegradation pathway of TYL including desugarification, hydrolysis, and reduction reactions was proposed through the analysis of biodegradation products. It was demonstrated that strain Y13 gradually decreased the biotoxicity of TYL and its metabolites based on the results of the ecological structural activity relationships (ECOSAR) model analysis and toxicity assessment. Moreover, Y13 promoted the reduction of the target macrolide resistance genes in wastewater and disappeared within 84 h. These results shed new light on the mechanism of TYL biodegradation and better utilization of microbes to remediate TYL contamination.

[Expression and purification of recombinant SARS coronavirus spike protein].

A novel coronavirus (SARS-coronavirus, SARS-CoV) was discovered in association with cases of severe acute respiratory syndrome (SARS) recently. The first step in coronavirus infection is binding of the viral spike protein to certain receptor on host cells. The spike protein is the main surface antigen of the coronavirus and there should be antibodies against spike protein in patients serum. Thus, to develop and expression protein fragment from spike protein gene are the purposes of this experiment. Partial spike gene fragments (751-1925 bp, 2005-3410 bp, 1-1925 bp and 32-3659 bp) and its intact gene were cloned into pET32 or pGEX vectors, and transformed into competent Escherichia coli BL21(DE3) (pLysS), respectively. 63, 78, 98, 160 and 164 kD fusion proteins were successfully expressed with amounts of 35%, 34%, 24%, 17% and 5% of total cell protein. The soluble parts of the cell crude extract were then partially purified by GST affinity chromatography.

[Expression of human intestinal trefoil factor in Pichia pastoris and its biological activity on intestinal epithelium in vitro].

In order to produce relatively large amounts of recombinant human intestinal trefoil factor and assess its biological activity. The expression plasmid pPIC9-hITF containing AOX1 promotor and the sequences of secreting signal peptides was transformed into the yeast cells. Then through selection, positive transformants were cultivated in fermentation basal salts medium in a 5L fermenter to obtain large amount product with low cost. The secreted peptides were then purified by a combination of ionic exchange chromatography and molecular sieve. To verify the product, electrospray mass spectrometry analyses was used to determine the structure of rhITF and Western Blotting was performed to test the immunological activity. Furthermore, the biological activity of the peptide was examined by experiments from cell to tissue. The nucleotide sequence of rhITF was the same as expected. With a 5-L fermenter, 253mg of hITF was isolated at the purity of 96% from 3.5 L of yeast fermentation broth. The expression level for recombinant human ITF in this yeast system was 73.33mg/L. In our study, we provided a way to gain a production among milligram to gram of recombinant human ITF by the use of a yeast expression system. As human ITF are difficult to purify in any significant amount from tissue extraction, the way described may become a valuable tool in obtaining pure peptide for further studies of trefoil peptide function.