Effects of spray drying on the content of crystal proteins of Bacillus thuringiensis and the protection by organic and inorganic auxiliaries.

Spray drying is an important industrial method for the preparation of B. thuringiensis powder from fermentation liquor. The effect of spray drying on the crystal proteins, however, has not been reported in the literature so far. The present study systematically investigated the effect of inlet air temperature, outlet air temperature, atomizing air pressure and additives (including organic and inorganic auxiliaries) on the thermal destruction of crystal proteins of B. thuringiensis. The results indicated that the content of crystal proteins of B. thuringiensis powder decreased with increased inlet air temperature, outlet air temperature and atomising air pressure. The pseudo-z values for inlet air temperature, outlet air temperature and atomizing air pressure were 826.4 â„ƒ, 204.0 â„ƒ and 4.74 MPa, respectively. Among them, the outlet air temperature was a major parameter influencing the thermal destruction of crystal proteins, therefore, the decrease of the outlet air temperature was beneficial to increase the protein content in powder. Although the spray drying had an adverse effect on crystal proteins, the crystal protein content in spray-dried powder approached that in freeze-dried powder when the inlet air temperature of 165 â„ƒ, outlet air temperature of 70 â„ƒ and atomizing air pressure of 0.15 MPa were employed. The addition of some organic and inorganic auxiliaries to fermentation liquor can protect the crystal proteins from heat damage.

Discussion on the thermodynamic calculation and adsorption spontaneity re Ofudje et al. (2023).

Accurate calculations and precise results are very important for the dissemination of scientific knowledge, whereas the errors of calculation will diminish the academic value of the paper. This discussion focuses on the calculation of thermodynamics and the determination of the spontaneity of adsorption processes in the paper of Ofudje et al. (2023). Ofudje et al. found that the apatite synthesized by chemical method (CHAp) has excellent adsorption properties for cadmium ions, which is an important contribution to the remediation of cadmium pollution. However, the calculation results of standard Gibbs free energy change (ΔGo), standard enthalpy change (ΔHo) and standard entropy change (ΔSo) of the adsorption of Cd2+ onto CHAp surface need to be corrected due to an incorrect calculation. Firstly, the partition coefficient (KD) with a dimension cannot be used for thermodynamic calculation. Secondly, the adsorbent mass (m) described by Ofudje et al. in different Sections is inconsistent, leading to incorrect results of Ko and ΔGo. When the appropriate value of the adsorbent mass is selected and the partition coefficient is converted to the standard adsorption equilibrium constant Ko, the calculated ΔGo is less than zero, which means that the adsorption is spontaneous. This discussion provides the correct calculation method of standard adsorption equilibrium constants and thermodynamic parameters, which can improve the reader's judgment and understanding of adsorption spontaneity.

Effects of ageing time on the properties of polysaccharide in tangerine peel and its bacterial community.

To evaluate the effect of aging time on the quality of tangerine peel (TP) from the perspective of TP polysaccharide (TPP), five polysaccharide samples with different aging times named TPP-0/1/5/10/15 were prepared. Under the conditions of pH 0.5, solid-liquid ratio 1:25 and 80 °C, the TPPs extraction yield ranged from 20.35% to 27.68%. Compared with TPP-0, TPP-1/5/10/15 possesses low molecular weight (Mw) and high methoxy group content. In addition, TPP-15 had the most potent antioxidant activity. And the content of acidic polysaccharides in TPPs was negatively correlated with neutral polysaccharides during aging. Based on the analysis of 16srDNA, the dominant bacteria (Brevundimonas and Pseudomonas) in TP-10 might be critical flora to affect TP quality. This study provided basic information on the relationship between the TPPs and aging time, which could promote a new view to develop TP, and shorten the aging time during TP production.

Development of Carcinoembryonic Antigen Rapid Detection System Based on Platinum Microelectrode.

Rapid and highly sensitive detection of carcinoembryonic antigen (CEA) in blood could effectively improve the diagnostic sensitivity of colorectal cancer. In this work, a platinum microelectrode (PtµE) modified with gold nanoparticles was developed as a microsensor for the detection of CEA. As the recognition element, a CEA aptamer modified with sulfhydryl could be conjugated onto the surface of the PtµEs/Au. The quantitative analysis of the concentration of CEA [CEA] by the prepared PtµEs/Au aptasensor was carried out through square wave voltammetry. Under the optimized conditions, the PtµEs/Au aptasensor exhibits a linear response toward [CEA] in the range of 1.0 × 10-11-1.0 × 10-7 g/ml (S = 5.5 nA/dec, R 2 = 0.999), and the detection limit is 7.7 × 10-12 g/ml. The PtµEs/Au aptasensor also has good selectivity against other types of proteins existing in blood. The availability of the developed assay toward [CEA] in blood samples was investigated, and the results agreed well with those obtained through electrochemiluminescence provided by the hospital, and the volume of the blood sample for detection is only 20 µl. Herein, the proposed detection system could be used for the quantitative analysis of CEA in blood, with the advantages of high sensitivity, short time, and low cost. Moreover, the PtµEs/Au aptasensor has a potential application in clinical diagnosis.