Vol 8, No 1 (2023)

Table of Contents

Opinion

127 Views, 29 PDF Downloads
Ji-Dong Gu
DOI:10.26789/AEB.2023.01.007

Abstract

Biodegradation is still an active research topic for bioremediation development and clean up the contaminated sites, but current research reports have not dealt with this subject effectively to advance the basic science and provide a fundamental basis for applications. Degradation study is based on the availability of metabolically capable microorganisms, and then the biotransformation and degradation by them shall be on the further in-depth results of the biochemical pathway through isolation and identification of the degradation intermediates. In addition, the relevant genes and proteins can be also investigated based on the biodegradation reactions. There are a number of pitfalls on the degradation research and results reported currently, but the microbes and the metabolism shall be identified as the central focal points to advance the science of this topic prior to the application can be tested under different scenarios.

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49-52

Research Articles

248 Views, 59 PDF Downloads
Athar Hussain, Manjeeta Priyadarshi, Shivani Patel, Gaurav Saini
DOI:10.26789/AEB.2023.01.006

Abstract

Recent advances in anaerobic digestion has resulted in expansion of sustainable methods for use of waste as energy resources. Conventional methods prove to be uneconomical and environmentally impractical. Moreover, the microbial consortia in anaerobic digestion are temperature dependent and therefore requires investigations on temperature optimization. Therefore, the recent experimental study is being undertaken with the objective in order to assess the effect of temperature on anaerobic biodegradation of food wasted from a hostel campus. The effect of temperature on methane generation rate has also been investigated. The anaerobic digestion study under psychrophilic, mesophilic and thermophilic temperature conditions has been carried out and compared in order to assess the optimum methane production conditions. All the experimental study for anaerobic digestion of food waste has been carried out at optimum F/M (food to mass) ratio of 0.75. The cumulative highest methane production is observed to be 33, 50 and 65 mL of CH4 in reactor R1, R2 and R3 with initial food waste COD dosage of 100, 150 and 200 mg, respectively under mesophilic temperature conditions. The highest biochemical methane potential (BMP) value of 0.94, 0.95 and 0.93 gCH4-COD/gCOD fed in reactor R1, R2 and R3 respectively, under mesophilic temperature conditions. It been observed that for maximum methane generation rate constant of 0.62 d-1 were observed under thermophilic conditions thus has to be highly accelerative process but overall conversion of organic matter to methane is less as compared to mesophilic temperature conditions, this is because free ammonia concentration increases with increasing temperature, by influencing the equilibrium. However, mesophilic conditions provide a more stable environment for the anaerobic digestion process. This may be due to the fact that temperature fluctuations can disrupt the microbial activity and slow down the process, but mesophilic conditions provide a stable environment for the microorganisms to thrive. Therefore, the mesophilic temperature range provides a balance between high reaction rates, stability, and cost-effectiveness, making it the optimal temperature range for anaerobic digestion of food waste. The obtained results in present study will be helpful in implementing on full-scale anaerobic solid waste digesters for enhancing the methane generation under mesophilic temperature conditions with high organic matter removal. Also, under thermophilic conditions the energy requirement for heating proves to be uneconomical.

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41-48
147 Views, 45 PDF Downloads
Jihai Shao, Li Fan, Ye Feng
DOI:10.26789/AEB.2023.01.005

Abstract

In order to elucidate the toxicity of NH4+ on Nostoc Sphaeroides (commonly named GE-XIAN-MI in China, GXM), a diazotrophic cyanobacterium in paddy fields, this study investigated the growth, photosynthesis, N2-fixation, and oxidative-antioxidative characteristics of GXM under NH4+ stress in paddy floodwater. The results showed that the photosynthesis and the N2-fixing ability of GXM were inhibited by NH4+ at a concentration of 13.46 mg L-1 in paddy floodwater. The main target of NH4+ on photosystem II (PS II) of GXM was the electron donor side of react center. Oxygen evolution complex (OEC) was the secondary target of toxicity of NH4+ on PS II. The damage of PS II led to accumulation of ROS and resulted in oxidative damage on plasma membrane of GXM. Feedback inhibition and decrease of photosynthetic energy production may be the reasons for the decrease of N2-fixing ability of GXM under NH4+ stress. The results presented in this study suggest that high level of NH4+ loading may be a reason for the recession of GXM resource in paddy fields.

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32-40
120 Views, 30 PDF Downloads
Baghle Nitish, Sudan Jebi, Himanshi Mangla, Aruna Sharma, Saurabh Dave, Hardik Pathak
DOI:10.26789/AEB.2023.01.004

Abstract

The CRISPR /CAS system is a modern genome editing tool derived from a bacterium as it functions as an active immune system to prevent the bacteria from the viruses and plasmids. In the earlier years before the discovery of the CRISPR system, there were many other tools to perform genome editing but due to their low specificity and reliability, they were not considered an efficient tool. The discovery of CRISPR/CAS9 system overcomes these limitations and considered as a highly specific and efficient technique in the field of genome editing or DNA alteration. The purpose of studying the CRISPR/CAS system is to develop a powerful gene-editing tool that can make every possible gene editing and also to prevent the genomic defect in a certain group of organisms. The CRISPR/CAS9 system uses an RNA molecule which is a main functional part of the CRISPR through which a bacterial cell can recognize and cleave/destroy the foreign viral elements that enter the bacterial cell using a certain group of restriction nuclease enzymes isolated from different bacteria. Several repairing mechanisms in the cell have been used to ligate the degraded viral sequences as these repair mechanisms are error-prone and generate frame shift mutations in the sequence. As a result, the foreign viral components and their expressions were reduced or deleted. The purpose of this review is to understand the mechanism of bacterial CRISPR/CAS9 system and also to know the use of this technique to prevent single genomic defects. In this review discuss the role of the CRISPR/CAS9 system as an active immune system of bacterial cells, classifications, and the CRISPR/CAS9 system (type II) use in the genome-editing mechanism.

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25-31
132 Views, 43 PDF Downloads
Rania Al-Groom
DOI:10.26789/AEB.2023.01.003

Abstract

Background: Lactobacilli have been crucial for the production of fermented products for centuries. They are also members of the mutualistic microbiota present in the human gastrointestinal and urogenital tract. Recently, increasing attention has been given to their probiotic, health-promoting capacities. Objectives: The purpose of this study was to (a) evaluate the antibacterial and antibiofilm activities of Lactobacillus salivarius (ATCC 11741) and Lactobacillus casei (ATCC 9595) against Escherichia coli; and (b) assess the anti-virulence potential of these probiotics, by examining their impacts on the expression of selected genes in the test organism. Materials and Methods: The antibacterial, antibiofilm and antivirulence activities of L. salivarius and L. casei against E. coli were investigated by agar well diffusion, microtiter plate, crystal violet assay, quantitative real-time polymerase chain reaction (qPCR) analysis. Results: Susceptibility testing indicated antibacterial and antibiofilm activities of L. salivarius and L. casei against E. coli. Agar inhibition assay showed that L. salivarius and L. casei has antibacterial activity against E. coli with an inhibition zone of 21±2 mm and 24±1 mm respectively. The L. salivarius and L. casei were found to degrade and inhibit E. coli biofilm. All biofilm-forming cells treated with L. salivarius and L. casei supernatants showed reduced expression of genes involved in biofilm formation and quorum sensing. The expression of yjfO (bsmA), csgA, ycfR (BhsA), tnaA, lsrA, and rpoS genes of E.  coli was decreased, 0.75-fold, 0.65-fold, 0.5-fold, 0.73-fold, 1.2-fold and 0.85-fold respectively after exposure to L. salivarius, while the expression of yjfO (bsmA), csgA, ycfR (BhsA), tnaA, lsrA, and rpoS genes of E.  coli was decreased, 1.0-fold, 0.75-fold, 0.5-fold, 0.82-fold, 1.4-fold and 0.9-fold respectively after exposure to L. casei. Conclusion: The results of this study indicate that L. salivarius and L. casei strains showed a good antibacterial and antibiofilm against E. coli. Generally, present study suggested that the L. salivarius and L. casei strains exhibits a good antimicrobial activity.

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18-24
365 Views, 163 PDF Downloads
Shi-Peng Li, Yu-Xi Feng, Xiao-Zhang Yu
DOI:10.26789/AEB.2023.01.002

Abstract

The presence of microplastics (MPs) and nanoplastics (NPs) in the environment is ubiquitous, and as such, the toxicity of these plastics, exposure scenarios, and mechanisms of plant response is to be determined. Hereby, a meta-analysis is performed to investigate the effects of MPs and/or NPs on different plant species under hydroponics and soil conditions to assess the current scenario. We examined the response level of root system, photosynthetic parameters, and antioxidant system of plants against MPs/NPs. Root response level in soil condition against various concentrations and types of MPs was higher than in hydroponics however, this response was opposite for the types of MPs. Photosynthetic parameters, including chlorophyll a and b, carotenoids, total chlorophyll, and maximum quantum efficiency of PSII were higher in soil conditions than in hydroponics. Antioxidant parameters, such as malondialdehyde (MDA) and H2O2 contents were higher in hydroponics plants, while, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) showed a mix trend of response level. In addition, proline content was significantly higher in soil and ascorbic acid (ASA) in hydroponic cultured plants under different types, sizes, and concentrations of MPs. These three systems i.e., root, photosynthesis, and antioxidant parameters were also compared between different species, however, the results are generally consistent with the above mentions one. Overall, these analyses suggest that plants grown in hydroponics are more sensitive to the plastic pollution than in the soil environment. 

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9-17
420 Views, 124 PDF Downloads
Hafidh Al Mahrouqi, Sergey Dobretsov, Roberto Tefilo Abdala-Daz
DOI:10.26789/AEB.2023.01.001

Abstract

Tilapia is the second most farmed fish in tropical and sub-tropical countries worldwide. This study investigated the effect of replacing fish meal by Spirulina platensis (groups fed with 5%, 10% and 15% Spirulina) on the growth of Nile tilapia O. niloticus juveniles. Intestinal microbiota of tilapia has been studied by MiSeq Illumina sequencing. No significant differences (P > 0.05) were observed for the protein, carbohydrate and lipids of fish fed with control food and different concentrations of spirulina. However, the Margalef species richness of the intestinal bacteria of tilapia fed with spirulina was significantly higher (P < 0.05) compared to the control samples. Evenness was significantly higher (P < 0.05) for tilapia fed with food substituted with the highest concentration of spirulina. Also, few potentially probiotic genera, like Bacillus and Actinomycetes were detected in the gut of the experimented Tilapia. On the other hand, the highest percent of potentially pathogenic genera was recorded for the genera Pseudomonas and Corynebacterium. In most cases, the highest abundances of potentially pathogenic species were found in control samples. As manipulation of the feed was shown to improve Tilapia microbiota, which could lead to further improvements in aquaculture production.

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