Biodegradability during Anaerobic Fermentation Process Impacted by Heavy Metals

In the past decades, biotechnologies for reutilizing the biomass harvested from the metal-contaminated land draw attention to many scientists. Among those technologies, anaerobic fermentation is proven as an efficient conversion process for biowaste reduction with simultaneous recovery of biogas as an energy source. During the process of anaerobic fermentation, the release of metals from the biomass will impact the growth and performance of microorganisms in reactors, which then results the variation of substrate degradation. In this chapter, the impact of metals on the degradation of substrate at different stages of fermentation process, as indicated by variations of lignocelluloses, chemical oxygen demands (COD), volatile fatty acids (VFAs), etc., will be summarized. The objective is to rationalize the relationship between metal presence and substrate degradability and give suggestions for future research on metal-contaminated biomass reutilization

How to write an honest but effective abstract for scientific papers

Due to lack of training in scientific writing and sometimes unethical practices, abstracts are often poorly written, lack critical information, and sometimes contain spin. An effective abstract provides brief but adequate information on the purpose, procedure, results and implications of a study. This paper discusses the key components of a good abstract, offers recommendations on reducing spin in abstracts, and analyzes three abstracts written by the author with the goal of helping young researchers write honest and effective abstracts

Chiral pharmaceutical drug adsorption to natural and synthetic particulates in water and their desorption in simulated gastric fluid

Natural and synthetic particulates in aquatic environments can act as a vector for chiral pharmaceutical drugs. Understanding enantiomer enrichment in the particulate phase of water matrices is essential considering the enantiospecific effects that chiral drugs can have on exposed organisms. Therefore, the enantiospecific adsorption of the cationic drugs fluoxetine and propranolol to polyhydroxyalkanoate bioplastic, polyamide microplastic, and cellulose particulates was investigated in 0.01 M calcium chloride (CaCl2) buffer and real environmental matrices. Fluoxetine enantiomers adsorbed to all particulate types under all conditions studied. Yet, propranolol only adsorbed to polyamide in 0.01 M CaCl2 buffer at pH 11, and in samples prepared using real matrices (river water and wastewater). No enantioselectivity was observed in the adsorption of fluoxetine or propranolol, or their subsequent desorption in a simulated gastric environment. Findings showed the enantiomeric composition of the adsorbed drug will reflect that of the dissolved drug assuming no degradation takes place. However, further enantiospecific adsorption studies are now needed on a broader range of chiral drugs and particulate matter found in water. Importantly, drug adsorption was considerably greater in river water and wastewater compared to 0.01 M CaCl2 buffer (2.1 to 5.3 times for fluoxetine). Most adsorption studies reported in the literature use 0.01 M CaCl2 buffer to conform with international guidelines for assessing the adsorption behaviour of chemicals. Although such conditions enable direct comparison with similar studies, they can underestimate cationic drug adsorption to particulates in engineered and natural environments. This needs consideration in future studies on drug adsorption to microplastics and other particulate matter in laboratory studies

Effects of norfloxacin, copper, and their interactions on microbial communities in estuarine sediment

The discharge of antibiotics and metals in estuaries is of great concern since they threaten microbial communities that are critical for maintaining ecosystem function. To understand single and combined effects of norfloxacin (0–20 μg g−1) and copper (40 μg g−1) on microbial ecology in estuaries, we evaluated changes in bacteria population, inhibition rates, and microbial composition in estuarine sediments over a 28-day period. Bacteria population significantly decreased following single and combined exposure to norfloxacin and copper throughout the incubation period, except on Day 28 in treatments exposed to copper, 20 μg g−1 norfloxacin, or both. These three treatment groups had lower Shannon diversity and Simpson's indices on Day 28 than other treatments and the controls suggesting recovery in bacteria population did not correspond with recovery in richness and evenness. Furthermore, functional predictions revealed that the effect of time and contaminants were significantly different on some microbial community functions on Day 28, especially the combination of Cu and high concentration NFX, including aerobic chemoheterotrophy, methanol oxidation and methylotrophy. Thus, norfloxacin and copper had significant adverse effects on microbial communities in estuarine sediments; however, the combined effects were variable and depended on exposure duration and antibiotic concentration

High Throughput Sediment DNA Sequencing Reveals Azo Dye Degrading Bacteria Inhabit Nearshore Sediments

Estuaries and coastal environments are often regarded as a critical resource for the bioremediation of organic pollutants such as azo dyes due to their high abundance and diversity of extremophiles. Bioremediation through the activities of azoreductase, laccase, and other associated enzymes plays a critical role in the removal of azo dyes in built and natural environments. However, little is known about the biodegradation genes and azo dye degradation genes residing in sediments from coastal and estuarine environments. In this study, high-throughput sequencing (16S rRNA) of sediment DNA was used to explore the distribution of azo-dye degrading bacteria and their functional genes in estuaries and coastal environments. Unlike laccase genes, azoreductase (azoR), and naphthalene degrading genes were ubiquitous in the coastal and estuarine environments. The relative abundances of most functional genes were higher in the summer compared to winter at locations proximal to the mouths of the Hanjiang River and its distributaries. These results suggested inland river discharges influenced the occurrence and abundance of azo dye degrading genes in the nearshore environments. Furthermore, the azoR genes had a significant negative relationship with total organic carbon, Hg, and Cr (p < 0.05). This study provides critical insights into the biodegradation potential of indigenous microbial communities in nearshore environments and the influence of environmental factors on microbial structure, composition, and function which is essential for the development of technologies for bioremediation in azo dye contaminated sites

Risk factors associated with a high incidence of sexually transmitted infections in Beitbridge, Zimbabwe

BACKGROUND: Sexually transmitted infections (STIs) are a major public health challenge, particularly in developing countries where the health infrastructure is often poor. Despite having a number of interventions in Beitbridge (such as the 24-h wellness centre), Zimbabwe, the incidence and prevalence of STIs is increasing. OBJECTIVES: This study, therefore, aims to assess the risk factors associated with the high incidence of STIs in urban Beitbridge. METHOD: A case-control study was conducted on 30 respondents who had suffered from STIs (selected from the registers at Beitbridge hospital and followed up) and 90 respondents who had not suffered from STIs (from the community) who resided in Beitbridge for at least 6 months and this excluded all those who were in transit. The factors contributing to the high incidence of STIs were identified using a pretested interviewer-administered semi-structured questionnaire in conjunction with a Likert scale to establish the attitudes and risk behaviours of the respondents on STIs. RESULTS: A significant association was observed between high STI incidences and the nature of occupation (odds ration [OR]: 3.8), area of residence (OR: 2.78), number of sexual partners (OR: 7.56), payment demanded for sex (OR 22), condom use (OR: 3.7), alcohol use (OR: 2.86), and suspicion that partners had other sexual companions (OR: 15.5). Furthermore, a larger proportion of controls were knowledgeable on STIs as compared to the cases who participated in the study. CONCLUSION: There is a need to develop awareness strategies that foster safe sexual practices, particularly among populations who do not choose abstinence or a single sexual partner lifestyle

Spatial distribution and ecological risks of polychlorinated biphenyls in a river basin affected by traditional and emerging electronic waste recycling in South China

With development of e-waste related legislation in China, formal recycling activities are designated in some areas while informal ones are illegally transferred to emerging areas to avoid supervision. However, the resulting environmental impact and ecological risks are not clear. Here, we investigated the discharge of polychlorinated biphenyls (PCBs) to soil and aquatic environments by e-waste recycling activities in the Lian River Basin, China. The study area included a designated industrial park in the traditional e-waste recycling area (Guiyu, known as the world's largest e-waste center), several emerging informal recycling zones, and their surrounding areas and coastal area. A total of 27 PCBs were analyzed, and the highest concentration was found in an emerging site for soil (354 ng g−1) and in a traditional site for sediment (1350 ng g‐−1) respectively. The pollution levels were significantly higher in both the traditional and emerging recycling areas than in their respective upstream countryside areas (p = 0.0356 and 0.0179, respectively). Source analysis revealed that the traditional and emerging areas had similar PCB sources mainly associated with three PCB technical mixtures manufactured in Japan (KC600) and the USA (Aroclor 1260 and Aroclor 1262). The PCB pollution in their downstream areas including the coastal area was evidently affected by the formal and informal recycling activities through river runoff. The ecological risk assessments showed that PCBs in soils and sediments in the Lian River Basin could cause adverse ecotoxicological consequences to humans and aquatic organisms

Enantioselectivity in degradation and ecological risk of the chiral pesticide ethiprole

Intensive agricultural activities have caused land degradation due to soil pollution, particularly by pesticides. However, the degradation, metabolism, and toxicity of chiral pesticides by soil microorganisms are often enantioselective. This study aimed to determine the effect of chirality on the degradation of the enantiomers of ethiprole in soil and their impact on soil microbial communities. (R)-ethiprole underwent directional chiral conversion to the (S)-enantiomer in a paddy soil microcosm, leading to elevated concentrations of (S)-ethiprole. Initially, the bacterial operational taxonomic units significantly decreased after 3 days of incubation with rac-ethiprole, (R)-ethiprole, and (S)-ethiprole but gradually increased in the later stage. Principal coordinate analysis revealed that the bacterial community structure was enantioselectively affected by the ethiprole enantiomers. Within 3 days, both rac-ethiprole and (R)-ethiprole reshaped the original stochastic microbial community into a deterministic community (variable selection). Thus, we propose that the enantioselective behavior and ecotoxicology of chiral pesticides need to be considered, especially because there are numerous chiral pesticides currently in use within agricultural management. The comprehensive understanding of the ecological risk of chiral pesticide enantiomers is vital to the process of improving sustainable production and environmental health in agricultural ecosystems

B vitamins supplementation induced shifts in phytoplankton dynamics and copepod populations in a subtropical coastal area

IntroductionB vitamins play a crucial role in shaping phytoplankton and zooplankton communities in marine ecosystems, yet their impact on community dynamics remains poorly understood.MethodsWe carried out in situ incubation experiments of B vitamins supplementation to explore the response pattern of phytoplankton and zooplankton community compositions.ResultsThe results showed that vitamins B1, B2, B6 and B12 promoted the growth of phytoplankton, and the total Chl α in 87.5% of the supplemented B vitamin treatments showed a significant positive response (p &lt; 0.05). Supplementation with these B vitamins significantly altered the community composition of phytoplankton, and 75% of the B vitamin-supplemented treatments showed an increase in the relative abundance of Minutocellus, Thalassiosirales, Odontella, Prymnesiales and Ditylum, considered mainly to be the result of B vitamin auxotrophy. In contrast, a significant decrease in Copepoda, including Calanoida and Cyclopoida, was observed in 87.5% of treatments. The observed shifts in community composition were attributed to the auxotrophy of certain diatoms and Prymnesiales for B vitamins. These shifts subsequently led to negative correlations (Spearman Rho &lt; -0.8) between the abundance of these phytoplankton species and Copepoda populations.DiscussionThese findings advance our understanding of the complex interactions between micronutrient availability and plankton community dynamics