Organic acids are organic compounds that can be synthesized using biological systems. They often contain one or more low molecular weight acidic groups, such as carboxyl group and sulphonic group. Organic acids are widely used in food, agriculture, medicine, bio-based materials industry and other fields. Yeast has unique advantages of biosafety, strong stress resistance, wide substrate spectrum, convenient genetic transformation, and mature large-scale culture technology. Therefore, it is appealing to produce organic acids by yeast. However, challenges such as low concentration, many by-products and low fermentation efficiency still exist. With the development of yeast metabolic engineering and synthetic biology technology, rapid progress has been made in this field recently. Here we summarize the progress of biosynthesis of 11 organic acids by yeast. These organic acids include bulk carboxylic acids and high-value organic acids that can be produced naturally or heterologously. Finally, future prospects in this field were proposed.
Saccharomyces cerevisiae/metabolism* ; Organic Chemicals ; Carboxylic Acids/metabolism* ; Metabolic Engineering ; Fermentation ; Acids

Aromatic compounds are a class of organic compounds with benzene ring(s). Aromatic compounds are hardly decomposed due to its stable structure and can be accumulated in the food cycle, posing a great threat to the ecological environment and human health. Bacteria have a strong catabolic ability to degrade various refractory organic contaminants (e.g., polycyclic aromatic hydrocarbons, PAHs). The adsorption and transportation are prerequisites for the catabolism of aromatic compounds by bacteria. While remarkable progress has been made in understanding the metabolism of aromatic compounds in bacterial degraders, the systems responsible for the uptake and transport of aromatic compounds are poorly understood. Here we summarize the effect of cell-surface hydrophobicity, biofilm formation, and bacterial chemotaxis on the bacterial adsorption of aromatic compounds. Besides, the effects of outer membrane transport systems (such as FadL family, TonB-dependent receptors, and OmpW family), and inner membrane transport systems (such as major facilitator superfamily (MFS) transporter and ATP-binding cassette (ABC) transporter) involved in the membrane transport of these compounds are summarized. Moreover, the mechanism of transmembrane transport is also discussed. This review may serve as a reference for the prevention and remediation of aromatic pollutants.
Humans ; Adsorption ; Bacteria/metabolism* ; Organic Chemicals ; Biological Transport ; ATP-Binding Cassette Transporters ; Polycyclic Aromatic Hydrocarbons/metabolism*

OBJECTIVES: To study the correlation of the expression of Lipin1 in visceral adipose tissue and Lipin2 in liver tissue with hepatic fat content in rats with intrauterine growth retardation (IUGR). METHODS: Pregnant rats were given a low-protein (10% protein) diet during pregnancy to establish a model of IUGR in neonatal rats. The pregnant rats in the control group were given a normal-protein (21% protein) diet during pregnancy. The neonatal rats were weighed and liver tissue was collected on day 1 and at weeks 3, 8, and 12 after birth, and visceral adipose tissue was collected at weeks 3, 8, and 12 after birth. The 3.0T ¹H-magnetic resonance spectroscopy was used to measure hepatic fat content at weeks 3, 8, and 12 after birth. Real-time PCR was used to measure mRNA expression levels of Lipin2 in liver tissue and Lipin1 in visceral adipose tissue. Western blot was used to measure protein levels of Lipin2 in liver tissue and Lipin1 in visceral adipose tissue. A Pearson correlation analysis was performed to investigate the correlation of mRNA and protein expression of Lipin with hepatic fat content. RESULTS: The IUGR group had significantly higher mRNA and protein expression levels of Lipin1 in visceral adipose tissue than the control group at weeks 3, 8, and 12 after birth (P<0.05). Compared with the control group, the IUGR group had significantly lower mRNA and protein expression levels of Lipin2 in liver tissue on day 1 after birth and significantly higher mRNA and protein expression levels of Lipin2 at weeks 1, 3, 8, and 12 after birth (P<0.05). At week 3 after birth, there was no significant difference in hepatic fat content between the IUGR and control groups (P>0.05), while at weeks 8 and 12 after birth, the IUGR group had a significantly higher hepatic fat content than the control group (P<0.05). The protein and mRNA expression levels of Lipin1 were positively correlated with hepatic fat content (r=0.628 and 0.521 respectively; P<0.05), and the protein and mRNA expression levels of Lipin2 were also positively correlated with hepatic fat content (r=0.601 and 0.524 respectively; P<0.05). CONCLUSIONS Upregulation of the mRNA and protein expression levels of Lipin1 in visceral adipose tissue and Lipin2 in liver tissue can increase hepatic fat content in rats with IUGR and may be associated with obesity in adulthood.
Adult ; Animals ; Female ; Fetal Growth Retardation ; Gene Expression ; Humans ; Liver/metabolism* ; Organic Chemicals ; Pregnancy ; RNA, Messenger/metabolism* ; Rats

Xanthomonas albilineans (Ashby) Downson is a quarantine pest for importing plants to China that causes leaf scald bacterial disease on sugarcane. X. albilineans produces a potent phytotoxin/antibiotic called albicidin. As a pathogenic factor, albicidin causes typical white leaf stripes by inhibiting plastid DNA gyrase and disturbing chloroplast differentiation. Meanwhile, the antibacterial activity of albicidin gives X. albilineans a competitive advantage against rival bacteria during their colonization. Furthermore, albicidin has a rapid bactericidal activity against a variety of Gram-positive and Gram-negative pathogenic bacteria of human species at nanomolar concentrations, making it a potential antimicrobial drug for clinical application. This article reviews the advances of albicidin from the aspects of its molecular structure, traditional extraction methods, mechanism of action, biosynthetic genes and processes, chemical synthesis method and improvement, in order to provide insights into the prevention and treatment of the sugarcane leaf scald disease, and the development of new antibiotics.
Anti-Bacterial Agents/pharmacology* ; China ; Humans ; Organic Chemicals ; Xanthomonas/genetics*

Resource utilization is an effective way to cope with the rapid increase of kitchen waste and excess sludge, and volatile fatty acids produced by anaerobic fermentation is an important way of recycling organic waste. However, the single substrate limits the efficient production of volatile fatty acids. In recent years, volatile fatty acids produced by anaerobic co-fermentation using different substrates has been widely studied and applied. In this paper, we analyze the characteristics of fermentation to produce acid using kitchen waste and excess sludge alone or mixture. Influences of environmental factors and microbial community structure on the type and yield of volatile fatty acids in the anaerobic fermentation system are discussed in detail. Moreover, we propose future research directions, to provide a reference for recycling kitchen waste and excess sludge.
Anaerobiosis ; Bioreactors ; Fatty Acids, Volatile ; Fermentation ; Hydrogen-Ion Concentration ; Microbiota ; Organic Chemicals ; Sewage

Tetracarbon organic acids are important platform chemicals that are widely used in the food, chemical, medicine, material industries and agriculture. Compared with the traditional petrochemical process, the production of tetracarbon organic acids by microbial fermentation is more promising due to milder reaction conditions, greener process and better environmental compatibility. This review summarizes the biosynthetic pathways and metabolic mechanisms for the production of tetracarbon organic acids, and illustrates recent advances, challenges, and future perspectives in the production of tetracarbon organic acids by naturally selected or purposefully engineered strains.
Acids ; Biosynthetic Pathways ; Fermentation ; Metabolic Engineering ; Organic Chemicals

Mitochondrial function is crucial for the maintenance of cellular homeostasis under physiological and stress conditions. Thus, chronic exposure to environmental chemicals that affect mitochondrial function can have harmful effects on humans. We argue that the concept of hormesis should be revisited to explain the non-linear responses to mitochondrial toxins at a low-dose range and develop practical methods to protect humans from the negative effects of mitochondrial toxins. Of the most concern to humans are lipophilic chemical mixtures and heavy metals, owing to their physical properties. Even though these chemicals tend to demonstrate no safe level in humans, a non-linear dose-response has been also observed. Stress response activation, i.e., hormesis, can explain this non-linearity. Recently, hormesis has reemerged as a unifying concept because diverse stressors can induce similar stress responses. Besides potentially harmful environmental chemicals, healthy lifestyle interventions such as exercise, calorie restriction (especially glucose), cognitive stimulation, and phytochemical intake also activate stress responses. This conceptual link can lead to the development of practical methods that counterbalance the harm of mitochondrial toxins. Unlike chemical hormesis with its safety issues, the activation of stress responses via lifestyle modification can be safely used to combat the negative effects of mitochondrial toxins.
Dementia ; Diabetes Mellitus, Type 2 ; Environmental Exposure ; Environmental Pollutants ; Homeostasis ; Hormesis ; Humans ; Life Style ; Metals, Heavy ; Mitochondria ; Nonlinear Dynamics ; Organic Chemicals

With the increasing occurrence of haze during the summer, the physicochemical characteristics and toxicity differences in PM_2.5 in different seasons are of great concern. Hangzhou is located in an area that has a subtropical monsoon climate where the humidity is very high during both the summer and winter. However, there are limited studies on the seasonal differences in PM_2.5 in these weather conditions. In this test, PM_2.5 samples were collected in the winter and summer, the morphology and chemical composition of PM_2.5 were analyzed, the toxicity of PM_2.5 to human bronchial cells BEAS-2B was compared, and the correlation between PM_2.5 toxicity and the chemical composition was discussed. The results showed that during both the winter and summer, the main compounds in the PM_2.5 samples were water-soluble ions, particularly SO₄^2-, NO₃^-, and NH₄⁺, followed by organic components, while heavy metals were present at lower levels. The higher the mass concentration of PM_2.5, the greater its impact on cell viability and ROS levels. However, when the mass concentration of PM_2.5 was similar, the water extraction from the summer samples showed a greater impact on BEAS-2B than that from the winter samples. The cytotoxicity of PM_2.5 was closely associated with heavy metals and organic pollutants but less related to water-soluble ions.
Air Pollutants/toxicity* ; Bronchi/metabolism* ; Carbon/chemistry* ; Environmental Monitoring ; Humans ; Ions ; Metals, Heavy ; Organic Chemicals ; Particle Size ; Particulate Matter/toxicity* ; Seasons ; Temperature ; Water

BACKGROUND: Construction painters have not been studied well in terms of their hazards exposure. The objective of this study was to evaluate the exposure levels of total volatile organic compounds (TVOCs) for painters in the construction industry. METHODS: Activity-specific personal air samplings were carried out in three waterproofing activities [polyurethane (PU), asphalt, and cement mortar] and three painting activities (epoxy, oil based, and water based) by using organic-vapor-monitor passive-sampling devices. Gas chromatograph with flame ionization detector could be used for identifying and quantifying individual organic chemicals. The levels of TVOCs, by summing up 15 targeted substances, were expressed in exposure-index (EI) values. RESULTS: As arithmetic means in the order of concentration levels, the EIs of TVOCs in waterproofing works were 10.77, 2.42, 1.78, 1.68, 0.47, 0.07, and none detected (ND) for indoor PU-primer task, outdoor PU-primer task, outdoor PU-resin task, indoor PU-resin task, asphalt-primer task, asphalt-adhesive task, and cement-mortar task, respectively. The highest EI for painting works was 5.61 for indoor epoxy-primer task, followed by indoor epoxy-resin task (2.03), outdoor oil-based-spray-paint task (1.65), outdoor water-based-paint task (0.66), and indoor oil-based-paint task (0.15). Assuming that the operations were carried out continuously for 8 hours without breaks and by using the arithmetic means of EIs for each of the 12 tasks in this study, 58.3% (7 out of 12) exceeded the exposure limit of 100% (EI > 1.0), while 8.3% (1 out of 12) was in 50-100% of exposure limit (0.5 > EI > 1.0), and 4 tasks out of 12 were located in less than 50% of the limit range (EI < 0.5). CONCLUSION: From this study, we recognized that construction painters are exposed to various solvents, including carcinogens and reproductive toxins, and the levels of TVOC concentration in many of the painting tasks exceeded the exposure limits. Construction workers need to be protected from chemical agents during their painting works by using personal protective devices and/or work practice measures. Additional studies should focus on the exposure assessment of other hazards for construction workers, in order to identify high-risk tasks and to improve hazardous work environments.
Carcinogens ; Construction Industry ; Flame Ionization ; Humans ; Organic Chemicals ; Paint ; Paintings ; Protective Devices ; Solvents* ; Volatile Organic Compounds ; Water

Bio-based materials are new materials or chemicals with renewable biomass as raw materials such as grain, legume, straw, bamboo and wood powder. This class of materials includes bio-based polymer, biobased fiber, glycotechnology products, biobased rubber and plastics produced by biomass thermoplastic processing and basic biobased chemicals, for instance, bio-alcohols, organic acids, alkanes, and alkenes, obtained by bio-synthesis, bio-processing and bio-refinery. Owing to its environmental friendly and resource conservation, bio-based materials are becoming a new dominant industry taking the lead in the world scientific and technological innovation and economic development. An overview of bio-based materials development is reported in this special issue, and the industrial status and research progress of the following aspects, including biobased fiber, polyhydroxyalkanoates, biodegradable mulching film, bio-based polyamide, protein based biomedical materials, bio-based polyurethane, and modification and processing of poly(lactic acid), are introduced.
Biomass ; Biotechnology ; Organic Chemicals ; Plastics ; Polymers ; Rubber