Bioaccumulation of heavy metals from aqueous solution using indigenous fungal isolates

499-507Twenty six fungal strains were isolated from heavy metals contaminated soil of which A. flavus (F4) and R. pusillus (F6) were the most dominant. Growth of isolates were noticed by Pb, Cr and Cd concentration in the growth medium in one- step and two- step process, thus about seven isolates can grow upto 10mg (Pb,Cr, Cd)/100ml medium. The formulation of Sabouraud dextrose broth (SDB) medium fortified the isolates by ingredients and favored the best growth yields that have the highest biosorption, compared to Chashi medium (CM) and Yeast peptone glucose (YPG) medium. Thus, 99% of Pb and Cr were absorbed in biosorption medium containing 10mg Pb and Cr in 100ml medium while 77% of Cd was absorbed in the biosorption medium containing 10mg Cd in 100ml medium. Uptake capacity of resistant fungal isolates against heavy metals was checked in different medium. With respect to Pb, Cd and Cr maximum uptake of 39.58, 68.02 and 68.87mg.g-1 was observed by fungi Rhizomucor pusillus (F6) and Aspergillus flavus (F4). This indicated the potential of these identified fungi as biosorbent for removal of high concentration metals from soil and industrial effluents and also it was observed that efficiency of two-step process is better than the one-step process

Quorum Sensing Bacteria in the Phycosphere of HAB Microalgae and Their Ecological Functions Related to Cross-Kingdom Interactions

It has been proven that the relationship between microalgae and bacteria affects the dynamic process of harmful algal blooms (HABs). Microalgae-associated microorganisms widely exist in the phycosphere and play an essential role in algae-bacteria cross-kingdom interactions. Among these processes, quorum sensing (QS), as a communication system of bacteria, is thought to participate in algae-bacteria interactions. However, the species of QS bacteria in the phycosphere and their ecological function are still unknown. In this study, microalgae-associated microorganisms with a QS system were screened by the biosensor method and identified based on 16S rRNA gene analysis. The types and number of acyl-L-homoserine lactone (AHL) signalling molecules produced by QS bacteria were analysed by thin layer chromatography (TLC) bioautography and gas chromatography-mass spectrometer (GC-MS). The film formation, β-dimethylmercaptopropionic (DMSP) degradation and algae growth effects of QS bacteria were investigated. The results showed that 113 QS bacteria were isolated from 842 microalgae-associated bacteria. Detection of AHL molecules in 10 different species of QS bacteria showed that most of them were N-(3-Oxodecanoyl)-L-homoserine lactone (OC10-HSL), N-Octanoyl-L-homoserine lactone (C8-HSL) and N-(3-Oxooctanoyl)-L-homoserine lactone (OC8-HSL). All 10 QS bacteria had film-forming ability, and they could degrade DMSP (except strain E26). The crude metabolic extracts of the 10 QS bacteria can inhibit or promote microalgae growth to different degrees. Our study is helpful to understand the role of microalgae-associated microorganisms with the QS system in algae-bacteria interactions and community succession of HAB microalgae

Enhancement of SARS-CoV-2 N Antigen-Specific T Cell Functionality by Modulating the Autophagy-Mediated Signal Pathway in Mice

The frequent SARS-CoV-2 variants have caused a continual challenge, weakening the effectiveness of current vaccines, and thus it is of great importance to induce robust and conserved T cellular immunity for developing the next-generation vaccine against SARS-CoV-2 variants. In this study, we proposed a conception of enhancing the SARS-CoV-2 specific T cell functionality by fusing autophagosome-associated LC3b protein to the nucleocapsid (N) (N-LC3b). When compared to N protein alone, the N-LC3b protein was more effectively targeted to the autophagosome/lysosome/MHC II compartment signal pathway and thus elicited stronger CD4+ and CD8+ T cell immune responses in mice. Importantly, the frequency of N-specific polyfunctional CD4+ and CD8+ T cells, which can simultaneously secrete multiple cytokines (IFN-γ+/IL-2+/TNF-α+), in the N-LC3b group was significantly higher than that in the N alone group. Moreover, there was a significantly improved T cell proliferation, especially for CD8+ T cells in the N-LC3b group. In addition, the N-LC3b also induced a robust humoral immune response, characterized by the Th1-biased IgG2a subclass antibodies against the SARS-CoV-2 N protein. Overall, these findings demonstrated that our strategy could effectively induce a potential SARS-CoV-2 specific T cellular immunity with enhanced magnitude, polyfunctionality, and proliferation, and thus provided insights to develop a promising strategy for the design of a novel universal vaccine against SARS-CoV-2 variants and other emerging infectious diseases

Co-Metabolic Mechanism Analysis of Sulfidogenesis and Acidogenesis for Mariculture Solid Waste Treatment: Key Functional Microorganisms and Enzymes

Sulfidogenesis is a non-negligible process during the acidogenic fermentation of mariculture solid waste (MSW), and its interactions with acidogenesis are still unclear. To fill this gap, this study explored the co-metabolism mechanisms of acidogenesis and sulfidogenesis during the acidogenic fermentation of MSW with thermal (TH) pretreatment, alkaline fermentation (AF), and their combination (TH-AF) pretreatment. The interactions of sulfidogenesis and acidogenesis were altered by the changes in substrate availability and fermentation environment under the intervention of TH and AF pretreatments. Both acidogenesis and sulfidogenesis were boosted with TH pretreatment by supplying adequate substrates, and their competition for substrates was alleviated. Moreover, sulfidogenesis was constrained by 87.3% with TH-AF pretreatment, which reduced volatile fatty acid (VFA) consumption by sulfate reduction bacteria (SRB) and further enhanced the VFA accumulation. Notably, acidogenesis could be promoted by sulfidogenesis due to the enhancement of MSW hydrolysis and enrichment of acidogenic bacteria (Prolixibacter, Ruminococcus, etc.). Different pretreatments could redirect the metabolic pathways by changing the types of key functional microorganisms and enzymes in MSW anaerobic fermentation. Overall, this study provides useful information for developing an efficient and sustainable treatment of MSW

Effect of Magnet Powder (Fe₃O₄) on Aerobic Granular Sludge (AGS) Formation and Microbial Community Structure Characteristics

Magnet powder (Fe₃O₄) could affect the growth and biodegradation ability of microbes by producing a magnetic field and iron ion. In this study, the enhancement of aerobic granulation by adding Fe₃O₄ was performed to evaluate the effects of different Fe₃O₄ concentrations (0, 0.4, 0.8, 1.2, and 1.6 g/L) on sludge granulation. Fe₃O₄ had a positive effect on the formation and growth of aerobic granular sludge (AGS) during the start-up period. In addition, the Fe₃O₄ concentration at 0.4–1.2 g/L promoted COD removal compared to the sequencing batch reactor (SBR) without Fe₃O₄. The three-dimensional–excitation emission matrix (3D–EEM) indicated that 0.8 g/L Fe₃O₄ addition could accelerate the granulation by stimulating extracellular polymeric substance (EPS) secretion which was an advantage for enhancing granule size. Meanwhile, microbial richness and diversity of AGS was significantly affected with Fe₃O₄ addition by high-throughput sequencing. Furthermore, dominant groups contributing to granule formation, COD removal, and nitrifying–denitrifying were identified under different Fe₃O₄ concentrations