Enhancing Pseudomonas cell growth for the production of medium-chain-length polyhydroxyalkanoates from Antarctic krill shell waste.

Antarctic krill shell waste (AKSW), a byproduct of Antarctic krill processing, has substantial quantity but low utilization. Utilizing microbial-based cell factories, with Pseudomonas putida as a promising candidate, offers an ecofriendly and sustainable approach to producing valuable bioproducts from renewable sources. However, the high fluoride content in AKSW impedes the cell growth of P. putida. This study aims to investigate the transcriptional response of P. putida to fluoride stress from AKSW and subsequently conduct genetic modification of the strain based on insights gained from transcriptomic analysis. Notably, the engineered strain KT+16840+03100 exhibited a remarkable 33.7-fold increase in cell growth, capable of fermenting AKSW for medium-chain-length-polyhydroxyalkanoates (mcl-PHA) biosynthesis, achieving a 40.3-fold increase in mcl-PHA yield compared to the control strain. This research advances our understanding of how P. putida responds to fluoride stress from AKSW and provides engineered strains that serve as excellent platforms for producing mcl-PHA through AKSW.

Engineering the ß-Oxidation Pathway in Yarrowia lipolytica for the Production of trans-10, cis-12-Conjugated Linoleic Acid.

trans-10, cis-12-Conjugated linoleic acid (t10, c12-CLA) is an octadecadienoic acid with various biological benefits. Previously, linoleic acid isomerase from Propionibacterium acnes (PAI) was overexpressed in Yarrowia lipolytica (Y. lipolytica) to produce t10, c12-CLA. However, the t10, c12-CLA yield was restricted by the peroxisomal ß-oxidation pathway. In this study, to minimize the degradation of t10, c12-CLA, four genetically modified strains of Y. lipolytica (Δpox2-oPAI, Δpox3-oPAI, Δpox2Δpox3-oPAI, and Δpex10-oPAI) were constructed and compared in terms of production stability and yield of t10, c12-CLA using safflower seed oil as substrates. The Δpex10-oPAI strain exhibited the best results, as revealed by the reduction of the t10, c12-CLA degradation rate from 58.5 to 18.6 mg/L/h. Additionally, the YLUpex10mP recombinant strain bearing six copies of oPAI combined with PEX10 deletion enhanced t10, c12-CLA production to 7.4 g/L and exhibited a CLA degradation rate of 19.7 mg/L/h, a 78% decrease from that of the control strain. Finally, in a bioreactor containing low-cost volatile fatty acids as partial carbon sources, the t10, c12-CLA content in the YLUpex10mP strain increased to 9.7 g/L, 1.3 times higher than in flasks. To our knowledge, this is the highest t10, c12-CLA yield through microbial synthesis reported to date.

Easily fabricated and lightweight PPy/PDA/AgNW composites for excellent electromagnetic interference shielding.

Conductive polymer composites (CPCs) containing nanoscale conductive fillers have been widely studied for their potential use in various applications. In this paper, polypyrrole (PPy)/polydopamine (PDA)/silver nanowire (AgNW) composites with high electromagnetic interference (EMI) shielding performance, good adhesion ability and light weight are successfully fabricated via a simple in situ polymerization method followed by a mixture process. Benefiting from the intrinsic adhesion properties of PDA, the adhesion ability and mechanical properties of the PPy/PDA/AgNW composites are significantly improved. The incorporation of AgNWs endows the functionalized PPy with tunable electrical conductivity and enhanced EMI shielding effectiveness (SE). By adjusting the AgNW loading degree in the PPy/PDA/AgNW composites from 0 to 50 wt%, the electrical conductivity of the composites greatly increases from 0.01 to 1206.72 S cm-1, and the EMI SE of the composites changes from 6.5 to 48.4 dB accordingly (8.0-12.0 GHz, X-band). Moreover, due to the extremely low density of PPy, the PPy/PDA/AgNW (20 wt%) composites show a superior light weight of 0.28 g cm-3. In general, it can be concluded that the PPy/PDA/AgNW composites with tunable electrical conductivity, good adhesion properties and light weight can be used as excellent EMI shielding materials.

Sodium selenosulfate at an innocuous dose markedly prevents cisplatin-induced gastrointestinal toxicity.

Our previous studies in mice revealed that two weeks short-term toxicity of sodium selenosulfate was significantly lower than that of sodium selenite, but selenium repletion efficacy of both compounds was equivalent. In addition, we showed that sodium selenosulfate reduced nephrotoxicity of cisplatin (CDDP) without compromising its anticancer activity, thus leading to a dramatic increase of cancer cure rate from 25% to 75%. Hydration has been used in clinical practice to reduce CDDP-induced nephrotoxicity, but it cannot mitigate CDDP-induced gastrointestinal toxicity. The present work investigated whether sodium selenosulfate is a potential preventive agent for the gastrointestinal toxicity. In tumor-bearing mice, sodium selenosulfate was administered at a dose of 9.5 µmol/kg daily for 11 days, CDDP alone resulted in diarrhea by 88% on day 12, whereas the co-administration of CDDP and sodium selenosulfate dramatically reduced diarrhea to 6% (p<0.0001). Such a prominent protective effect promoted us to evaluate the safety potential of long-term sodium selenosulfate application. Mice were administered with sodium selenosulfate or sodium selenite for 55 days at the doses of 12.7 and 19 µmol/kg. The low-dose sodium selenite caused growth suppression and hepatotoxicity which were aggravated by the high-dose, leading to 40% mortality rate, but no toxic symptoms were observed in the two sodium selenosulfate groups. Altogether these results clearly show that sodium selenosulfate at an innocuous dose can markedly prevent CDDP-induced gastrointestinal toxicity.