Vol 7, No 1 (2022)

Table of Contents

Research Articles

277 Views, 47 PDF Downloads
Zimu Wang, Guolan Wang, Jieting Qu, Wen Hong, Ling Luo


The widespread antibiotic resistance genes (ARGs) severely jeopardizing human health have been widely concerned. Wastewater treatment plants (WWTPs) are commonly considered the important sources and sinks of ARGs due to their roles in depositing ARGs and provoking ARGs' proliferation. Current WWTPs often use biological treatment to remove pollutants, whereas the purification efficacy of ARGs is unclear. Thus, this study investigated the seasonal changes of ARGs (tetA, tetC, tetM, tetO, tetQ, tetW, and tetX, as representative) and a class of integron (intI1) in the sludge of different treatment units of four WWTPs to understand the role of WWPTs in ARGs spread. It is found that ARGs abundance varied between summer and winter depending on the types of ARGs and treatment units. The cumulative abundance of ARGs in the same treatment unit showed no obvious difference between seasons. By comparison, ARGs abundance was generally lower in the anoxic unit than in the oxic unit. Moreover, the WWTPs with Cyclic Activated Sludge System (CASS) process reduced the amount of ARGs in sludge, while the WWTPs with Anaerobic-Anoxic-Oxic (A2O) increased ARGs abundance. In conclusion, this study demonstrated that the excess sludge still posed a risk for ARG spread after biological treatment.

511 Views, 35 PDF Downloads
Mohammad A. Alkafaween, Hidaeyh Kafaween, Rania M. Al-Groom


Abstract: Honey is a natural product that has been widely used for its therapeutic effects. Honey is effective against pathogenic bacteria in inhibiting planktonic antibiotic sensitive strains and antimicrobial resistant organisms. To date, there is no comparative study of the antibacterial activity of Citrus honey (CH) and Jabali honey (JH) with that of Manuka honey (MH). Therefore, the purpose of this study was to conduct such study and to compare the antibacterial activity of CH and JH with that of MH against Pseudomonas aeruginosa. The antibacterial, antibiofilm and antivirulence activities of CH, JH and MH against P. aeruginosa were investigated by agar well diffusion, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), time-kill curve, disruption of microcolony, microtiter plate and reverse transcription-quantitative Quantitative Real-Time Polymerase Chain Reaction (RT-qPCR). Agar inhibition assay showed that CH, JH and MH at 20% has antibacterial activity against P. aeruginosa with an inhibition zone of 14.1±0.1 mm, 12.2±0.2 mm and 10.9±0.1 mm respectively. The results showed that the MICs value of CH and JH was 25% compared to MH (12.5%) and the MBCs value of CH and JH was 50% compared to MH (25%) against P. aeruginosa. In addition, the MIC50 and MIC90 for CH and JH were 25% and 50% respectively compared to MH (MIC50; 12.5% and MIC90; 25%) against P. aeruginosa. All tested honeys were found to disrupt the microcolony formation in P. aeruginosa. In time-kill curve, treatment of P. aeruginosa with 2×MIC (Minimum inhibitory concentration) of MH, CH and JH for 12-hours resulted in reduction in colony-forming unit (CFU/ml). The lowest concentration of 20% of MH, CH and JH was found to inhibit and eradicate biofilm formation. RT-qPCR analysis revealed that the expression of all genes (oprB, oprC, fleN, fleQ, fleR, lasR and lasI) in P. aeruginosa were downregulated after exposure to all tested honeys. Among the all-tested honeys, MH showed the highest total antibacterial, antibiofilm and antivirulence activities. This study indicates that CH and JH has antibacterial and antibiofilm activities compared with MH due to a decrease in expression of essential genes associated with P. aeruginosa.

460 Views, 139 PDF Downloads
Nguyen Khoi Nghia, Chau Thi Anh Thy, Le Thi Xa, Do Thanh Luan


The objective of the study was to utilize the biogas effluents to produce solid and liquid organic fertilizers, as well as evaluate their effect on the growth and yield of corn and mung beans under field conditions. For liquid organic fertilizer, biogas effluents were mixed with fish emulsion and beneficial bacteria while biogas effluents-absorbing coal slag was mixed with sugarcane filter, fishmeal and beneficial bacteria to create solid organic fertilizer. Liquid organic fertilizer was irrigated with a dose of 5 L/1000 m2 while solid organic fertilizer was applied with a dose of 1 ton/ha with 75% recommended NPK formula for maize and mung bean. The results showed that applying solid or liquid organic fertilizer formulated from biogas effluents with other amendments helped to reduce the amount of recommended NPK fertilizer by 25%, but still maintained growth and yield of maize and mungbean equivalent to the control treatment fertilized with 100% recommended NPK. In conclusion, the amount of organic matter and N, P, K in biogas effluents from biogas digesters can be utilized to produce organic fertilizers which not only help to reduce chemical fertilizers, but also solve the environmental problems and create new friendly value-added products for practicing sustainable agricultural production.

569 Views, 123 PDF Downloads
Mohammad A. Alkafaween, Mohammad Abu-Sini, Hamid A. Nagi Al-Jamal


Staphylococcus aureus is one of the most common pathogens in biofilm-associated chronic infections. S. aureus that live within biofilms avoid the host's immune response and are more resistant to antibiotics than planktonic bacteria. The current study was conducted to evaluate the antibacterial, antibiofilm and antivirulence of seven antibiotics (Ciprofloxacin (CP), Gentamicin (GEN), Tetracycline (TET), Amikacin (AMK), Clindamycin (CLI), Erythromycin (Ery) and Vancomycin (VAN) against S. aureus. The effects of seven antibiotics (CP, AMK, VAN, TET GEN, Ery and CLI) on S. aureus planktonic and biofilm were determined via Antibiotic susceptibility test, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), disruption of microcolony, biofilm inhibition and degradation (crystal violet staining) and RT-qPCR. Antibiotic susceptibility test showed that CP, AMK, VAN, TET GEN, Ery and CLI has antibacterial activity against S. aureus with an inhibition zone of 28 mm, 21 mm, 27 mm, 20 mm, 25 mm, 27 mm and 19 mm respectively. The results showed that CP and AMK possessed the lowest MIC value against S. aureus with 0.125 µg/mL and 0.25 µg/mL for VAN, TET and GEN and 1.0 for Ery and CLI. The recorded values for MBCs were 0.25 μg for CP and AMK for S. aureus, 0.5 μg for vancomycin, tetracycline and gentamicin for S. aureus and 1.0 μg for Ery and CLI for S. aureus. Notably, CP and AMK demonstrated considerable efficacy, as shown by the low values for MIC; 0.125 μg and MBC; 0.25 μg for S. aureus. All antibiotics were found to disrupt microcolony formation in S. aureus at MIC of each antibiotics. At 0.25 μg concentration to 8 μg concentration of each antibiotic were significantly found to degrade and inhibit biofilm formation of S. aureus. The RT-qPCR showed that four genes including argF, purC, adh, and fabG were downregulated, whilst, three genes including scdA, pykA and menB were upregulated after exposure to CP, AMK, VAN, TET GEN, Ery and CLI. This study showed the efficacy of seven antibiotics against planktonic, biofilm, gene expression and that different concentrations of antibiotics have different degrees of potential effect on established biofilm. In addition, a decreased expression of virulence genes in S. aureus will impact their pathogenicity. These results provide the theoretical parameters for the selection of effective antimicrobial in clinical therapy and demonstrate how to correctly use antibiotics at MIC and sub-MIC as preventive drugs.



527 Views, 140 PDF Downloads
Ji-Dong Gu


Science is experiencing a different model for a wider dissemination with the widely accessibility of internet today at the information age and high connectivity. This technological development has changed the daily life of peoples globally and has been mainly appraised with positive effects, but very little, if any, negative ones are being discussed, specifically on fundamental matters. In this article I would like to present the emerging negativities and potential detrimental effects on science and its advances to be made. Popularization and population are two words chosen and used here to describe the way in which dissemination of available and accessible scientific information is being made. The new Open Access model of publication and its apparent dominance in the academic publishing market by commercial companies for publication of scientific papers are passing the threshold point and eroding the quality of science in my view. Scientific societies as the most important groups to the establishment of academic standards and to keep new science discoveries to be checked are increasingly forced to cope with the commercial publication practices in terms of speeding up the reviewing and publishing more and quickly, competing for the publishing market and profit to be made, and most importantly, compromising the academic standards. When profit is the major driving force for the publishers, including scientific societies, quality of science in academic papers is yielded to the financial interest and profit, and the purposes of publishing are not for science and its development as the goal. The role of scientific publication in our society must be checked by relevant administration of the governments and national academies together with the scientific societies so that the quality of academic publication of scientific results in science can be maintained at high confident level to serve the society in a positive manner into the future. Commercial publication is another avenue to allow more scientific results to be published in additional to journals by societies, but the relationship between them must be a quality-based judgement and decision, not a pure business competition for success to rule this market.


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