Comparative study of the extracellular proteome of Sulfolobus species reveals limited secretion

Although a large number of potentially secreted proteins can be predicted on the basis of genomic distribution of signal sequence-bearing proteins, protein secretion in Archaea has barely been studied. A proteomic inventory and comparison of the growth medium proteins in three hyperthermoacidophiles, i.e., Sulfolobus solfataricus, S. acidocaldarius and S. tokodaii, indicates that only few proteins are freely secreted into the growth medium and that the majority originates from cell envelope bound forms. In S. acidocaldarius both cell-associated and secreted α-amylase activities are detected. Inactivation of the amyA gene resulted in a complete loss of activity, suggesting that the same protein is responsible for the a-amylase activity at both locations. It is concluded that protein secretion in Sulfolobus is a limited process, and it is suggested that the S-layer may act as a barrier for the free diffusion of folded proteins into the medium

Macromolecular Fingerprinting of Sulfolobus Species in Biofilm: A Transcriptomic and Proteomic Approach Combined with Spectroscopic Analysis

Microorganisms in nature often live in surfaceassociated sessile communities, encased in a self-produced matrix, referred to as biofilms. Biofilms have been well studied in bacteria but in a limited way for archaea. We have recently characterized biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus, and S. tokodaii. These strains form different communities ranging from simple carpet structures in S. solfataricus to high density tower-like structures in S. acidocaldarius under static condition. Here, we combine spectroscopic, proteomic, and transcriptomic analyses to describe physiological and regulatory features associated with biofilms. Spectroscopic analysis reveals that in comparison to planktonic life-style, biofilm life-style has distinctive influence on the physiology of each Sulfolobus spp. Proteomic and transcriptomic data show that biofilm-forming life-style is strain specific (eg ca. 15% of the S. acidocaldarius genes were differently expressed, S. solfataricus and S. tokodaii had ∼3.4 and ∼1%, respectively). The -omic data showed that regulated ORFs were widely distributed in basic cellular functions, including surface modifications. Several regulated genes are common to biofilm-forming cells in all three species. One of the most striking common response genes include putative Lrs14-like transcriptional regulators, indicating their possible roles as a key regulatory factor in biofilm development

Real-Time Implementation of G.723.1 Speech Coder Using TMS320VC5402 DSP Chip

This paper presents a full duplex, real time implementation of ITU-T G.723.1 [7,8] speech coder using the TMS320C5402 DSP chip which is based on a 16 bit fixed-point architecture. An optimization method is proposed in order to reduce the total necessary cycle time consumed in real-time implementation. The Multi-Pulse Maximum Likelihood Quantization (MP-MLQ) excitation search block which is the most computation-intensive block in the coder is restructured to reduce the algorithmic redundancy. In addition, efficient filtering methods and memory management are used for further optimization. The bit-exact verification with the ITU test vectors and performance evaluation aspects are also discussed in this paper

Acidianus, Sulfolobus and Metallosphaera surface layers: structure, composition and gene expression

The cell walls of Sulfolobales species consist of proteinaceous S-layers assembled from two polypeptides, SlaA and SlaB. We isolated the large S-layer protein of Acidianus ambivalens and both S-layer subunits of Sulfolobus solfataricus and Metallosphaera sedula, respectively. The slaAB genes, lying adjacently in the chromosomes, are constitutively transcribed as bicistronic operons in A. ambivalens and S. solfataricus. A smaller slaA transcript appeared in Northern hybridizations of A. ambivalens RNA. PCRs experiments showed that 80–85% of the transcripts stop at an oligo-T terminator downstream of slaA while 15–20% are read through to a second terminator downstream of slaB. The bicistronic operons including promoter and terminator regions are conserved in the Sulfolobales. While no SlaA homologue is found outside the Sulfolobales, SlaB is distantly similar to S-layer proteins of other Crenarchaeota, e.g. the Staphylothermus marinus tetrabrachion. Molecular modelling suggests SlaBs to be composed of 2–3 consecutive beta sandwich domains, a coiled-coil domain of 15–17 nm in length and a C-terminal transmembrane helix. Electron microscopy shows crystalline protein arrays with triangular and hexagonal pores. We propose that the mushroom-shaped ‘unit cells’ of the Sulfolobales’ S-layers consist of three SlaBs anchoring the complex in the membrane and six SlaAs forming the detergent-resistant outer sacculus

Multi-walled carbon nanotubes-CoFe2O4 nanoparticles as a reusable novel peroxymonosulfate activator for degradation of Reactive Black 5

In this study, CoFe2O4 nanoparticles supported on multi-walled carbon nanotubes (MWCNTs), as novel peroxymonosulfate (PMS) activator, were synthesized for degradation of Reactive Black 5 (RB5). The results showed that the maximum removal efficiencies of RB5 (100), chemical oxygen demand (83.12), and total organic carbon (65.5) could happen at pH of 7, catalyst dosage of 100 mg/L, PMS dosage of 2 mM, RB5 concentration of 50 mg/L, and time of 30 min. The results of the temperature effect showed that the activation energy (Ea = 20.92 kJ/mol) for the synthesized catalyst is much lower compared to other studies. The PMS/MWCNTs-CoFe2O4 system had higher decolorization efficiency and kinetic rates compared to other adsorption and oxidation systems. Quenching experiments proved that RB5 was degraded by sulfate and hydroxyl radicals. The MWCNTs-CoFe2O4 catalyst showed suitable stability and reusability even after five consecutive catalytic reactions. The continuous treatment of RB5 in real water resources was performed using catalyst packed in a column reactor, and its results showed the high efficiency of the column in the catalytic treatment of the dye at long reaction time. Based on the proposed degradation pathway, the azo bands and the naphthalene structure of RB5 are oxidized to compounds with low molecular weight. Practitioner points: MWCNTs-CoFe2O4 was used as a novel recyclable catalyst for the activation of peroxymonosulfate and dye degradation. The rate of dye degradation and peroxymonosulfate activation by MWCNTs-CoFe2O4 was much higher than that of the catalysts alone. Radical (Formula presented.), with contribution percentage of 73.20, was the main agent for degradation of Reactive Black 5 dye. MWCNTs-CoFe2O4 in the dye degradation process showed excellent stability and reusability, lower activation energy, and easier separation. The dye degradation products were identified by gas chromatography and UV-vis spectrophotometric analyses, and their degradation pathway was suggested. © 2020 Water Environment Federatio

Improved antifouling and antibacterial properties of forward osmosis membranes through surface modification with zwitterions and silver-based metal organic frameworks

This study investigates the effect of surface functionalization of a thin-film composite forward osmosis membrane with zwitterions and silver-based metal organic frameworks (Ag-MOFs) to improve the antifouling, anti-biofouling, and antimicrobial activity of the membrane. Two types of zwitterions, namely, 3-bromopropionic acid and 1,3-propane sultone, are chemically bonded, with and without incorporation of Ag-MOFs, over the surface of a polyamide membrane. Spectroscopy measurements indicate successful grafting of the modifying agents on the membrane surface. Contact angle measurements demonstrate a notable improvement in surface wettability upon functionalization. The performance of the membranes is evaluated in terms of water and salt fluxes in forward osmosis filtrations. The transport data show demonstrably increased water flux of around 300% compared to pristine membranes, with similar or slightly reduced salt reverse flux. The antifouling and anti-biofouling properties of the modified membranes are evaluated using sodium alginate and E. coli, respectively. These experiments reveal that functionalized membranes exhibit significant antifouling and anti-biofouling behavior, with high resilience against flux decline