Microbial extraction of chitin from seafood waste using sugars derived from fruit waste-stream.

Chitin and chitosan are natural amino polysaccharides that have exceptional biocompatibility in a wide range of applications such as drug delivery carriers, antibacterial agents and food stabilizers. However, conventional chemical extraction methods of chitin from marine waste are costly and hazardous to the environment. Here we report a study where shrimp waste was co-fermented with Lactobacillus plantarum subsp. plantarum ATCC 14917 and Bacillus subtilis subsp. subtilis ATCC 6051 and chitin was successfully extracted after deproteinization and demineralization of the prawn shells. The glucose supplementation for fermentation was replaced by waste substrates to reduce cost and maximize waste utilization. A total of 10 carbon sources were explored, namely sugarcane molasses, light corn syrup, red grape pomace, white grape pomace, apple peel, pineapple peel and core, potato peel, mango peel, banana peel and sweet potato peel. The extracted chitin was chemically characterized by Fourier Transform Infrared Spectroscopy (FTIR) to measure the degree of acetylation, elemental analysis (EA) to measure the carbon/nitrogen ratio and X-ray diffraction (XRD) to measure the degree of crystallinity. A comparison of the quality of the crude extracted chitin was made between the different waste substrates used for fermentation and the experimental results showed that the waste substrates generally make a suitable replacement for glucose in the fermentation process. Red grape pomace resulted in recovery of chitin with a degree of deacetylation of 72.90%, a carbon/nitrogen ratio of 6.85 and a degree of crystallinity of 95.54%. These achieved values were found to be comparable with and even surpassed commercial chitin.

Microbial production of rhamnolipids using sugars as carbon sources.

Rhamnolipids are a class of biosurfactants with effective surface-active properties. The high cost of microbial production of rhamnolipids largely affects their commercial applications. To reduce the production post, research has been carried out in screening more powerful strains, engineering microbes with higher biosurfactant yields and exploring cheaper substrates to reduce the production cost. Extensive refining is required for biosurfactant production using oils and oil-containing wastes, necessitating the use of complex and expensive biosurfactant recovery methods such as extraction with solvents or acid precipitation. As raw materials normally can account for 10-30% of the overall production cost, sugars have been proven to be an alternative carbon source for microbial production of rhamnolipids due to its lower costs and straightforward processing techniques. Studies have thus been focused on using tropical agroindustrial crop residues as renewable substrates. Herein, we reviewed studies that are using sugar-containing substrates as carbon sources for producing rhamnolipids. We speculate that sugars derived from agricultural wastes rich in cellulose and sugar-containing wastes are potential carbon sources in fermentation while challenges still remain in large scales.

Phosphorylation and nuclear translocation of STAT3 regulated by the Epstein-Barr virus latent membrane protein 1 in nasopharyngeal carcinoma.

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncoprotein has been shown to mediate activation of the signal transducer and activator of transcription 3 (STAT3). In the present study, we delineated the mechanism by which LMP1 stimulates STAT3 in a human nasopharyngeal carcinoma (NPC) cell line. LMP1 stimulated STAT3 Tyr 705-dependent nuclear accumulation, as well as the phosphorylation of STAT3 at both Tyr 705 and Ser 727. Treatment of cells with interleukin-6 neutralizing antibody inhibited the phosphorylation of STAT3 Tyr 705 and Ser 727. The differential phosphorylation of STAT3 was found to be a result of activation of Janus kinase 3 (JAK3) and extracellular signal-regulated kinase (ERK). The biological significance of JAK3-mediated activation of STAT3 Tyr 705 phosphorylation was further assessed by treating the cells with an inhibitor (WHI-P131) of JAK3. Inhibition of ERK activity by an inhibitor (PD98059) of MAPK/extracellular signal-regulated kinase kinase (MEK1) decreased the LMP1-induced activation of STAT3 Ser 727. Furthermore, immunohistochemical analysis showed an increased nuclear STAT3 Tyr 705 staining in LMP1-positive cells and STAT3 Tyr 705 phosphorylation related to NPC stages III and IV. Demonstration of the involvement of different kinases in LMP1-induced STAT3 activation supports the involvement of the JAK/STAT and mitogen-activated protein kinase (MAPK)/ERK signaling pathways in the regulation of STAT3 activation by LMP1.

Heterodimer formation between c-Jun and Jun B proteins mediated by Epstein-Barr virus encoded latent membrane protein 1.

Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1) is essential for the immortalization of human B cells and is linked etiologically to several human tumors. LMP1 is an integral membrane protein which acts like a constitutively active receptor. It binds tumor necrosis factor (TNF)-receptor-associated factors (TRAFs), activates NFkappaB and triggers the transcription factor activating protein-1 (AP-1) via the c-Jun N-terminal kinase (JNK) cascade, but its specific contribution to AP-1 has not been elucidated fully. Members of AP-1 family, the Jun and fos related protein, have been shown to directly interact and form heterodimeric complexes. In this report, using a Tet-on LMP1 HNE2 cell line which is a dual-stable LMP1 integrated nasopharyngeal carcinoma (NPC) cell line and the expression of LMP1 in which could be regulated by Tet-on system, we show that Jun B can efficiently form a new heterodimeric complex with the c-Jun protein under the regulation of LMP1, phosphorylation of c-Jun (ser63, ser73) and Jun B involved in the process of the new heterodimeric form. We also find that this heterodimeric form can bind to the AP-1 consensus sequence. Transfection studies suggest that JNK interaction protein (JIP) could inhibit the heterodimer form of c-Jun and Jun B through blocking the AP-1 signaling pathway triggered by LMP1. The interaction and function between c-Jun protein and Jun B protein increase the repertoire of possible regulatory complexes by LMP1 that could play an important role in the regulation of transcription of specific cellular genes in the process of genesis of nasopharyngeal carcinoma.

Nuclear factor kappa B (NFkappaB) dependent modulation of Epstein-Barr virus latent membrane protein 1 (LMP1) in epidermal growth factor receptor (EGFR) promoter activity.

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncoprotein may cause multiple cellular changes, including the induction of epidermal growth factor receptor (EGFR) expression and the activation of the nuclear factor kappa B (NFkappaB) transcription factor. LMP1 increases the levels of both EGFR protein and mRNA but does not stabilize EGFR mRNA. Thus the effects of LMP1 are likely to be mediated by direct activation of the EGFR promoter. In this study, induction of LMP1 increased the EGFR in both protein and promoter levels in a dose dependent manner using tetracycline-regulated LMP1 expression in nasopharyngeal carcinoma (NPC) cell line. Mutational analysis of the LMP1 protein indicated that the C-terminal activation region-1 (CTAR1) domain was mainly involved in the EGFR promoter induction, while CTAR2 was necessary but not sufficient to induce EGFR promoter. Inhibition of LMP1 mediated NFkappaB activation by constitutive repressive inhibitory kappa B alpha (IkappaBalpha) marginally decreased EGFR promoter activity using transiently transfected IkappaBalpha dominant negative mutant. Promoter mutagenesis analysis demonstrated that two putative NFkappaB binding sites of EGFR promoter were very necessary for the transcriptional activity of EGFR induced by LMP1, the proximal NFkappaB binding site was more important than the distal NFkappaB binding site. Taken together, Epstein-Barr virus latent membrane protein 1 modulated the EGFR promoter activity in a NFkappaB dependent manner.

Epstein-Barr virus latent membrane protein 1 modulates epidermal growth factor receptor promoter activity in a nuclear factor kappa B-dependent manner.

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncoprotein may cause multiple cellular changes including the induction of epidermal growth factor receptor (EGFR) expression and activation of the NFkappaB transcription factor. LMP1 increases the levels of both EGFR protein and mRNA, but does not stabilize EGFR mRNA. Thus, the effects of LMP1 are likely to be mediated by the direct activation of the EGFR promoter. In this study, induction of LMP1 increased the EGFR in both protein and promoter levels in a dose-dependent manner using tetracycline-regulated LMP1 expression in nasopharyngeal carcinoma (NPC) cell line. Mutational analysis of the LMP1 protein indicated that the C-terminal activation region-1 (CTAR1) domain was mainly involved in the EGFR promoter induction, while CTAR2 was necessary but not sufficient to induce EGFR promoter. Inhibition of LMP1-mediated NFkappaB activation by constitutive repressive IkappaBalpha marginally decreased EGFR promoter activity using transiently transfected IkappaBalpha dominant negative mutant. Promoter mutagenesis analysis demonstrated that two putative NFkappaB binding sites of EGFR promoter were very necessary for the transcriptional activity of EGFR induced by LMP1, the proximal NFkappaB binding site was more important than the distal NFkappaB binding site, and both NFkappaB binding sites played a cooperative role. Taken together, Epstein-Barr virus latent membrane protein 1 modulated the EGFR promoter activity in a NFkappaB-dependent manner.