Odor Production Research Articles

The Odor Release Regularity of Livestock and Poultry Manure and the Screening of Deodorizing Strains.

Human living environments and health are seriously affected by the odor produced from fermentation of livestock and poultry manure. In order to reduce the odor pollution caused by livestock and poultry manure, efficient strains were screened and two methods were tried in this study. The orthogonal test design was used to analyze the gas produced by pig manure under different conditions of temperature, time, wheat straw doping amount and calcium carbonate doping amount. Then, according to ammonia, hydrogen sulfide and comprehensive odor removal effects, the high efficiency of deodorizing strains were screened. The results showed that pig manure produced the least odor when the temperature was 20 °C, added 0% calcium carbonate, 20% wheat straw and waited for 48 h. Three strains were screened to inhibit the odor production of pig manure: Paracoccus denitrificans, Bacillus licheniformis and Saccharomyces cerevisiae, showed that their highest removal rate of ammonia and hydrogen sulfide gas could reach 96.58% and 99.74% among them; while for three strains of end-control pig manure stench: Pichia kudriavzevii, P. denitrificans and Bacillus subtilis, the highest removal rate of ammonia and hydrogen sulfide gas reached 85.91% and 90.80% among them. This research provides bacteria resources as the high-efficiency deodorizing function for the source suppression and the end treatment of the odor gas of pig manure, which has high application value for the control of odor pollution.

Microbial growth and volatile organic compound (VOC) emissions from carpet and drywall under elevated relative humidity conditions

BackgroundMicrobes can grow in indoor environments if moisture is available, and we need an improved understanding of how this growth contributes to emissions of microbial volatile organic compounds (mVOCs). The goal of this study was to measure how moisture levels, building material type, collection site, and microbial species composition impact microbial growth and emissions of mVOCs. We subjected two common building materials, drywall, and carpet, to treatments with varying moisture availability and measured microbial communities and mVOC emissions.ResultsFungal growth occurred in samples at >75% equilibrium relative humidity (ERH) for carpet with dust and >85% ERH for inoculated painted drywall. In addition to incubated relative humidity level, dust sample collection site (adonis p=0.001) and material type (drywall, carpet, adonis p=0.001) drove fungal and bacterial species composition. Increased relative humidity was associated with decreased microbial species diversity in samples of carpet with dust (adonis p= 0.005). Abundant volatile organic compounds (VOCs) that accounted for >1% emissions were likely released from building materials and the dust itself. However, certain mVOCs were associated with microbial growth from carpet with dust such as C10H16H+ (monoterpenes) and C2H6SH+ (dimethyl sulfide and ethanethiol). CO2 production from samples of carpet with dust at 95% ERH averaged 5.92 mg hr-1 kg-1, while the average for carpet without dust at 95% ERH was 2.55 mg hr-1 kg-1.ConclusionMicrobial growth and mVOC emissions occur at lower relative humidity in carpet and floor dust compared to drywall, which has important implications for human exposure. Even under elevated relative humidity conditions, the VOC emissions profile is dominated by non-microbial VOCs, although potential mVOCs may dominate odor production.5qHJBwjppp9jyb9CEJTu9oVideo

THE FIRST REPORT OF GEOSMIN AND 2-METHYLISOBORNEOL PRODUCER CYANOBACTERIA FROM TURKISH FRESHWATERS

Water users consider the safety of water according to its aesthetic properties, primarily taste and odour. Geosmin (GEO) and 2-methylisoborneol (MIB) are the most common taste and odour compounds in freshwaters which cause an earthy and musty odour in water. Since human nose can detect these compounds in concentrations as low as 10 ng/L, it is essential to monitor drinking waters before consumer complaints and to produce a timely solution. Therefore, it is necessary to identify GEO and MIB producers to manage the problem at its source. Cyanobacteria are one of the main producers of these compounds in freshwater ecosystems. In this study, we analyzed 13 samples (9 cyanobacteria cultures from Bafa Lake, Elmalı Dam Lake, İznik Lake, Küçükçekmece Lake, Manyas Lake and Taşkısığı Lake, and 4 environmental water samples from Erfelek and Günpınar Waterfalls and Ömerli Dam Lake) for GEO and MIB production by HS-SPME (Head space-solid phase microextraction) coupled with GC-MS (gas chromatography-mass spectrometry). The presence of Cyanobacteria-specific GEO and MIB synthase genes were also analyzed by PCR (Polymerase Chain Reaction). Taste and odour production was confirmed in 2 samples by GC-MS while 4 samples yielded positive results by PCR. All positive samples were environmental samples (3 samples from waterfalls from Günpınar and Erfelek Waterfalls, 1 sample from Ömerli Dam Lake -a drinking water reservoir) which were dominated by Nostoc Vaucher ex Bornet & Flahault, Phormidium Kützing ex Gomont and Pseudanabaena Lauterborn. This is the first report of GEO and MIB producing cyanobacteria in Turkish freshwaters by combining microscopy, analytical and molecular techniques.

Sodium butyrate reduce ammonia and hydrogen sulfide emissions by regulating bacterial community balance in swine cecal content in vitro

Reducing the production of odor during swine breeding has attracted attention. Ammonia (NH3) and hydrogen sulfide (H2S) contributed to the odor emissions from swine breeding because NH3 emissions are high and hydrogen sulfide (H2S) has a low odor threshold. Sodium butyrate reduces the odor emissions caused by NH3 and H2S, but the corresponding mechanism is unclear. After mixing the feces of six fattening pigs, the mixture was used to process in vitro fermentation experiment. The purpose was researching the effect of sodium butyrate reduced NH3 and H2S emissions in swine cecal contents. The control group was denoted CK, and the treatment groups with different sodium butyrate concentrations (0.015%, 0.030% and 0.150%) were denoted L, M and H. The NH3, H2S, total gas production and physicochemical indexes were measured, and the bacterial communities in the fermented product were analyzed by 16 S rDNA sequencing. The results showed that group M reduced NH3, H2S and total gas production by 17.96%, 12.26% and 30.30%, respectively. Sodium butyrate promoted SO42- accumulation and lowered the pH. Importantly, sodium butyrate decreased the relative abundance of bacteria positively correlated with NH3 and H2S production, but increased the negatively correlated ones. Proteobacteria made a greater contribution to reducing emissions than did other bacterial phyla. Our results showed that adding 0.030% sodium butyrate can significantly reduce NH3 and H2S production, which occurred via alterations in the physicochemical indicators to adjust the abundance of the bacteria related to odor production, including Proteobacteria.

Complex mechanism of sulphane odour production in water heating and suitable remedial measures

Abstract Drinking or heated water can have a wide range of disturbing odours which have many various causes. A well known example is sulphane (hydrogen sulfide) odour, reminiscent of rotten eggs, which naturally occurs in some underground waters. Less known and hitherto unexplained is this odour arising from hot water in water heaters. As a response to complaints by consumers we investigated 14 sites and thanks to experimental work in one of these recognised a complex mechanism at work. For production of sulphane to occur in a water heater the following conditions must be met: presence of sulphate-reducing bacteria, presence of sulphates, reduction properties of water indicated by a very low nitrate content (highest value was 10 mg/L, mostly <2 mg/L), and presence of sacrificial magnesium anode. We identified four possible remedial measures, some of which are less effective or only short term, or have an undesirable side-effect (corrosion). The most effective measure was replacement of the magnesium anode for an aluminium or zinc anode, which retains the anticorrosion protection of the heater.

Effect evaluation of remediation in three typical rivers with Vallisneria natans under different pollution and spatial characterization of functional microorganisms

Submerged plants can improve water quality, but the evaluation of practical engineering applications and the research on the characterization of functional microorganisms in the ecosystem are still insufficient. Three typical rivers (gradient pollution, persistent point pollution, and non external pollution) planted with Vallisneria natans in Guangzhou, China, were selected for monitoring to evaluate the restoration effect by measuring ralated environmental parameters and pollutant indexes, while microbial sequencing was used to analyze the spatial characterization of functional microbial composition. The results showed that Haizhu wetland phase III had a higher pH (9–10) and Xinshichong had a relatively lower concentration of dissolved oxygen (0.23–6.29 mg/L) varied with the intensity of light. Nitrogen pollution level followed the order of Xinshichong > Haizhu wetland phase I > Haizhu wetland phase III generally. The nitrate removal rate in Haizhu wetland phase I reached over 88%. 16S rRNA sequencing analysis showed that the sediment, leaves, and water bodies had different microbial community structures and Proteobacteria were abundant in all samples. Cyanobacteria attached to the leaves of Vallisneria natans, thereby inhibiting the growth in the water and sediment. Sulfur and iron circulation functional bacteria were mainly found in the sediment, while iron-oxidizing bacteria also presented on the leaves. The sediment from Xinshichong also contained abundant methane-related functional bacteria. The distributions of nitrogen cycling-related functional bacteria in the sediment and water, and on the leaves varied according to the different pollution levels at the sites. Therefore, Vallisneria natans can regulate DO environment, improve water quality, and work as an important attachment site for functional microorganisms in the ecosystem to prevent the waterbodies from black and odor. Additional work will be necessary to explore the process on the production of black and odor and the synergistic mechanism of microorganisms.

Contribution of the volatile components from fresh egg, adult female and male of Pestarella tyrrhena to odour production

Abstract Shrimps, including Pestarella tyrrhena , are highly susceptible to deterioration whereas odour production has been indicated as one of the factors determining the perishability and bait potential of shrimps. In this study, volatile components generated from fresh egg, adult female and male of P. tyrrhena were assessed using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry to understand their contribution to odour production. Alkenes, alkynes, alcohols, aldehydes, a ketone, acids, esters, an amine, sulphur-containing and miscellaneous compounds were detected. Meanwhile, adult females and males of P. tyrrhena had a higher number of these volatile compounds. The detection of 2-methyl propan-1-ol with pungent odour only in the male sample of P. tyrhenna suggests that the male of this shrimp species may not completely attract fishes to hooks. Overall, the study established shrimp developmental stage and sex as additional factors influencing the production of volatile compounds, flavour/aroma/odour and fishing bait attributes of P. tyrrhena. Detection of N-nitrosodimethylamine (a carcinogen) in the shrimp samples, particularly the adult male, calls for caution in their direct human consumption and use as fishing bait.

Development of a New Deodorization Method of Herring Milt Hydrolysate: Impacts of pH, Stirring with Nitrogen and Deaerator Treatment on the Odorous Content.

Herring milt hydrolysate (HMH) presents the disadvantage of being associated with an unpleasant smell limiting its use. Thus, to develop a new effective and easy-to-use deodorization method, this research aimed to deepen the knowledge regarding the impacts of pH (pH 7 vs. pH 10), overnight stirring with nitrogen (+N vs. −N) and deaerator treatment (+D vs. −D) on the odorous content of HMH. This latter included dimethylamine (DMA), trimethylamine (TMA), trimethylamine oxide (TMAO) and the most potent odor-active compounds of HMH. Results showed that pH had a huge impact on the targeted compounds resulting in higher detected concentrations of DMA, TMA and TMAO at pH 10 than at pH 7 (p < 0.05) while the opposite trend was observed for the most potent odor-active compounds of HMH (p < 0.05). Moreover, independently of the pH condition, the overnight stirring with or without nitrogen had no impact (p > 0.05). Finally, the deaerator treatment was more effective to remove TMA and DMA at pH 10 than at pH 7 (p < 0.05) while the opposite trend was observed for the most potent odor-active compounds (p < 0.05). Sensory analysis confirmed that the application of pH 10 −N +D and pH 7 −N +D + alkalization pH 10 conditions led to the least odorous products (p < 0.05).

Odor discrimination in terrestrial and aquatic environments in California sea lions (Zalophus californianus) living in captivity

Pinnipeds, as any mammal species, use multimodal signals, including olfactory ones, to ensure vital functions. Thus, some pinniped species seem able to use olfaction in both social and foraging contexts and to discriminate between different odors in air including both natural and artificial odors, but studies on that topic remain scarce. Here, we studied the olfactory capabilities of California sea lions living in captivity at La Flèche Zoo (France) in both terrestrial and aquatic environments. We used two categories of odors: social odors (from familiar individuals of the same group, unfamiliar individuals from another Zoo, animal zookeepers and a terrestrial carnivore) and non-social odors (food and odors identified as repellents in certain vertebrates). Several behavioral parameters were measured and analyzed as the number and duration of contact with the odor, mouth openings, vocalizations (air only) and air bubble production (water only). Our results, although limited by the low number of animals monitored (n = 5), suggest that California sea lions are able to discriminate between different odors both in the air and under water. In the aquatic environment, the process allowing the perception of odors remains to be characterized. Applications to this work could be considered in captive conditions as well as in the wild.

Effect of Different Modified Atmosphere Packaging on the Quality of Mulberry Fruit (Morus alba L. cv Kokuso 21).

The control of temperature and gas composition is essential to maintain the fresh flavor and quality of perishable fruits like mulberry. This study presented a modified atmosphere experiment (MAP) for fresh fruit showing the potential benefits of innovative gas mixing with argon. The effects of MAP were studied on the physicochemical and qualitative attributes of mulberry preserved at 4 ± 1°C and 90 ± 5% R.H. Fresh mulberries were packaged with different gas combinations: MAP1 (4%O2+6%CO2+90%N2), MAP2 (10%O2+5%CO2+85%Ar), CTR1 (20.9%O2+0.04%CO2), and CTR2 (10%O2+5%CO2+85%N2). Changes in quality parameters were evaluated after 0, 4, 8, and 12 days of storage. Mulberries packaged with MAP had a lower weight loss than CTR samples which lost more than 80% of their initial weight. Furthermore, the results showed that the argon treatment was the best in keeping the fruit juice content, preserving its structure. Despite not showing great differences with MAP1 treatment, Ar allowed to maintain high TSS up to 8 storage days, slowed CO2 production. The sensory profile of mulberry fruit was not significantly affected by storage in modified atmospheres, and the production of potential unpleasant odors in MAP2 could not be perceived. The results of this study confirm that this innovative approach, using MAP technology, has a potential use in maintaining mulberry fruit quality for a longer time.

Emission characteristics and assessment of odors from sludge anaerobic digestion with thermal hydrolysis pretreatment in a wastewater treatment plant.

Anaerobic digestion (AD) with thermal hydrolysis pre-treatment (THP) is an effective sludge treatment method which provides several advantages such as enhanced biogas formation and fertilizer production. The main limitation to THP-AD is that hazardous odors, including NH3 and volatile sulfur compounds (VSCs), are emitted during the sludge treatment process. In order to develop strategies to eliminate odors, it is necessary to identify the key odors and emissions sites. This study identified production of NH3 (741.60g·dry sludge t-1) and VSCs (277.27g·dry sludge t-1) during sludge AD after THP, and measured emissions in each of the THP-AD sludge treatment sites. Odor intensity, odor active values, permissible concentration-time weighted average, and non-carcinogenic risks were also assessed in order to determine the sensory impact, odor contribution, and health impacts of NH3 and VSCs. The results revealed that odor pollution existed in all of the test sites, particularly in the sludge pump room and pre-dehydration workshop. NH3, H2S, and methyl mercaptan caused very strong odors, and levels of NH3 and H2S were enough to impact the health of on-site employees.

Reducing odor emissions from feces aerobic composting: additives.

Aerobic composting is a reliable technology for treating human and animal feces, and converting them into resources. Odor emissions in compost (mainly NH3 and VSCs) not only cause serious environmental problems, but also cause element loss and reduce compost quality. This review introduces recent progresses on odor mitigation in feces composting. The mechanism of odor generation, and the path of element transfer and transformation are clarified. Several strategies, mainly additives for reducing odors proven effective in the literature are proposed. The characteristics of these methods are compared, and their respective limitations are analyzed. The mechanism and characteristics of different additives are different, and the composting plant needs to be chosen according to the actual situation. The application of adsorbent and biological additives has a broad prospect in feces composting, but the existing research is not enough. In the end, some future research topics are highlighted, and further research is needed to improve odor mitigation and element retention in feces compost.

Limitation of nutrients stimulates musty odor production by Streptomyces sp. isolated from a tropical environment.

Musty odor production by actinomycetes is usually related to the presence of geosmin and 2-methylisoborneol (2-MIB), which are synthesized by enzymes encoded by the geoA and tpc genes, respectively. Streptomyces spp. strain S10, which was isolated from a water reservoir in Malaysia, has the ability to produce geosmin when cultivated in a basal salt (BS) solid medium, but no 2-MIB production occurred during growth in BS medium. Strain S10 could produce higher levels of geosmin when the phosphate concentration was limited to 0.05 mg/L, with a yield of 17.53 ± 3.12 ✕ 105 ng/L, compared with growth in BS medium. Interestingly, 2-MIB production was suddenly detected when the nitrate concentration was limited to 1.0 mg/L, with a yield of 1.4 ± 0.11 ✕ 105 ng/L. Therefore, it was concluded that phosphate- and nitrate-limiting conditions could induce the initial production of geosmin and 2-MIB by strain S10. Furthermore, a positive amplicon of geoA was detected in strain S10, but no tpc amplicon was detected by PCR analysis. Draft genome sequence analysis showed that one open reading frame (ORF) contained a conserved motif of geosmin synthase with 95% identity with geoA in Streptomyces coelicolor A3 (2). In the case of the tpc genes, it was found that one ORF showed 23% identity to the known tpc gene in S. coelicolor A3(2), but strain S10 lacked one motif in the N-terminus.

Mosquito Behavior and Vertebrate Microbiota Interaction: Implications for Pathogen Transmission.

The microbiota is increasingly recognized for its ability to influence host health and individual fitness through multiple pathways, such as nutrient synthesis, immune system development, and even behavioral processes. Most of these studies though focus on the direct effects microbiota has on its host, but they do not consider possible interactions with other individuals. However, host microbiota can change not only host behavior but also the behavior of other individuals or species toward the host. For example, microbes can have an effect on animal chemistry, influencing animal behaviors mediated by chemical communication, such as mosquito attraction. We know that host skin microbes play a major role in odor production and thus can affect the behavior of mosquitoes leading to differences in attraction to their hosts. Ultimately, the vector feeding preference of mosquitoes conditions the risk of vertebrates of coming into contact with a vector-borne pathogen, affecting its transmission, and thus epidemiology of vector-borne diseases. In this mini review, I provide an overview of the current status of research on the interaction between mosquito behavior and host skin microbiota, both in humans and other vertebrates. I consider as well the factors that influence vertebrate skin microbiota composition, such as sex, genetic makeup, and infection status, and discuss the implications for pathogen transmission.

Effect of processing methods on the volatile components of Ethmalosa fimbriata using a two‐dimensional gas chromatography‐time‐of‐flight mass spectrometry (GC × GC‐TOF‐MS) technique

Changes in fish odor are attributed to volatile compounds’ generation. In this study, the effect of three processing methods (boiling, sun-drying, and smoke-drying) on the volatile compounds produced from Ethmalosa fimbriata was investigated using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF-MS). For complete cooking, appropriate fish samples were boiled slowly in water, while sun-drying was achieved traditionally. An improved Altona-type smoking oven was utilized for the smoke-drying process. The experimental results revealed the production of alkene, alkyne, alcohol, ketone, acids, esters, amines, sulfur-containing, and miscellaneous volatile compounds. Although the selected processing methods were effective for preserving E. fimbriata from the release of some volatile compounds associated with fish spoilage, they also contributed to the release of other volatile compounds and odor production. Boiling and smoke-drying were specifically found to be efficient for the removal of the three amines detected in the fresh fish sample, including carcinogenic N-nitrosodimethylamine. Practical applications The current research describes the potential of the studied processing methods (boiling, sun-drying, and smoke-drying) to preserve E. fimbriata from the production of some volatile compounds associated with fish spoilage. Boiling and smoke-drying were specifically found promising for preserving fish against the release of carcinogenic N-nitrosodimethylamine.

Effects of Different Laying Hen Species on Odour Emissions.

Simple SummaryOdour emissions from the laying hen industry receive considerable attention because they influence the air quality, the efficiency of animal production and the health of workers. Recently, numerous researchers have hypothesized that the choice of animals may influence the emission of gases, which may be utilized as the basis for gas pollution reduction strategies in the future. The present study employed an in vitro fermentation technique to simulate gas production from the caecum to explore the effects of laying hen species on the production of ammonia (NH3) and hydrogen sulphide (H2S). The results showed that the Xinghua laying hen had the lowest odour gas production among the six laying hen species tested. Spearman correlation analysis showed that odour production was associated with enzyme activities but was not significantly associated with specific enzyme genes. The results of this study provide useful information for odour reduction in the laying hen industry.Odour is one of the main environmental concerns in the laying hen industry and may also influence animal health and production performance. Previous studies showed that odours from the laying hen body are primarily produced from the microbial fermentation (breakdown) of organic materials in the caecum, and different laying hen species may have different odour production potentials. This study was conducted to evaluate the emissions of two primary odorous gases, ammonia (NH3) and hydrogen sulphide (H2S), from six different laying hen species (Hyline, Lohmann, Nongda, Jingfen, Xinghua and Zhusi). An in vitro fermentation technique was adopted in this study, which has been reported to be an appropriate method for simulating gas production from the microbial fermentation of organic materials in the caecum. The results of this study show that Jingfen produced the greatest volume of gas after 12 h of fermentation (p < 0.05). Hyline had the highest, while Lohmann had the lowest, total NH3 emissions (p < 0.05). The total H2S emissions of Zhusi and Hyline were higher than those of Lohmann, Jingfen and Xinghua (p < 0.05), while Xinghua exhibited the lowest total H2S emissions (p < 0.05). Of the six laying hen species, Xinghua was identified as the best species because it produced the lowest total amount of NH3 + H2S (39.94 µg). The results for the biochemical indicators showed that the concentration of volatile fatty acids (VFAs) from Zhusi was higher than that for the other five species, while the pH in Zhusi was lower (p < 0.01), and the concentrations of ammonium nitrogen (NH4+), uric acid and urea in Xinghua were lower than those in the other species (p < 0.01). Hyline had the highest change in SO42− concentration during the fermentation processes (p < 0.05). In addition, the results of the correlation analysis suggested that NH3 emission is positively related to urease activities but is not significantly related to the ureC gene number. Furthermore, H2S emission was observed to be significantly related to the reduction of SO42− but showed no connection with the aprA gene number. Overall, our findings provide a reference for future feeding programmes attempting to reduce odour pollution in the laying hen industry.

Cutaneous Bacteria in the Gut Microbiome as Biomarkers of Systemic Malodor and People Are Allergic to Me (PATM) Conditions: Insights From a Virtually Conducted Clinical Trial

Background The skin is a dynamic ecosystem of microbes and the source of many chemical compounds that affect human health. Skin-microbiome interactions can cause persistent, psychosocially devastating body smell despite good hygiene. Since odor production is often transient, malodors may not be perceptible during medical examinations. Therefore, having odor complaints can be diagnosed as body dysmorphic disorder and referred for psychological evaluations. Development of simple at-home tests and virtual care programs could improve the diagnosis and management of socially debilitating malodor conditions. Objective The aim of this study was to assess potential effectiveness of at-home gut microbiome testing in the diagnosis and management of idiopathic body and breath odor and in people are allergic to me (PATM) syndrome. Methods We contacted participants of prior metabolic body odor (MEBO) and PATM studies and online support groups by email or social media. Individuals who consented to participate were mailed test kits for at-home collection of gut microbiome samples. Participants completed an online survey (specially developed for this study) addressing their symptoms and other quality-of-life indicators at baseline and after sampling. Participants collected stool samples after flare-ups or symptom improvements and mailed them to the laboratory to be processed and analyzed. We evaluated between-group differences in symptom severity, as well as symptom improvement observations for the same individuals. For differential abundance testing of microbial taxa, we performed nonparametric statistical analyses using Mann-Whitney U tests for unpaired samples and Wilcoxon signed rank test for paired samples. Results A total of 112 individuals from 21 countries consented to participate. About half the participants had been tested for the metabolic disorder trimethylaminuria, and about half of those tested were diagnosed with the disorder. The levels of bacteria previously associated with cutaneous body odor were significantly elevated in gut samples. For the combination of species from Anaerococcus, Corynebacterium, Campylobacter, and Propionibacterium genera, the differences were P=.002 for active (73 participants, 182 samples) versus regression or remission groups (30 participants, 51 samples); P=.01 for those experiencing symptoms most or all of the time (46 participants, 88 samples) versus those who had symptoms sometimes, rarely, or never (25 participants, 74 samples); and P&lt;.001 for improvement of symptoms in the same individuals (22 participants, 43 sets of matched samples). Changes in microbial diversity were significant for between- but not within-participant comparisons. Conclusions Changes in the gut microbiome composition affect MEBO and PATM severity. In particular, an increase in intestinal bacteria producing odor when in skin flexures was associated with increased intensity of self-reported symptoms. The changes were consistent in the within-group and between-group analyses. Our findings support the feasibility of remote and decentralized clinical studies of malodor conditions. Supplementary sample collection procedures may help to meet established research quality standards. Trial Registration ClinicalTrials.gov NCT03582826; http://clinicaltrials.gov/ct2/show/NCT03582826 International Registered Report Identifier (IRRID) RR2-10.1101/2020.08.21.20179242

Ecofriendly production of bioactive tissue engineering scaffolds derived from egg- and sea-shells

Managing the vast amounts of eggshell and sea-shell waste that is produced globally each year is becoming very problematic as this material is simply disposed of in landfills. This waste results in odor production and microbial growth directly leading to environmental stresses. Transforming this waste into valuable biomaterials pose significant environmental and economic advantages as discarded waste have materials that can be utilized. The objective of this work was to develop inexpensive, bioactive hydroxyapatite-based scaffolds for tissue engineering applications by using an eco-friendly and sustainable approach. Engineering nano hydroxyapatite (EnHA) was derived from chicken eggshell and clam sea-shell waste by using an energy efficient microwave assisted wet chemical precipitation method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), and Energy dispersive spectroscopy (EDS) were used to analyze the biomaterials. Results show that the particles are highly crystalline hydroxyapatite (HA) with acicular shapes and within nanometer size ranges. The chemical compositions match exactly that of naturally occurring HA. The EnHA infused polymer scaffolds were fabricated using slurry-based solution 3D printing techniques. The slurry solutions composed of 70 wt% EnHA and 30 wt% Polycarpolactone (PCL). The XRD, SEM, EDS, and in vitro cell studies were conducted to determine the ability of the scaffolds to support cell adhesion and maintain viability. The scaffolds supported cellular attachment and maintenance when observed over a period of several days, suggesting their potential for future tissue regeneration research and applications.

The Role of the Bacterial Community in Producing a Peculiar Smell in Chinese Fermented Sour Soup.

In this paper, the volatile flavour constituents and the bacterial diversity in characteristic Chinese fermented sour soup were analysed, and the dynamics of bacteria associated with the odour were characterized. The bacterial diversity of sour soup was studied by high-throughput sequencing. A total of 10 phyla and 89 genera were detected. Firmicutes was the dominant phylum of sour soup, accounting for 87.14–98.57%. The genus structure of normal sour soup was relatively simple, and Lactobacillus (78.05–90.26%) was the dominant genus. In addition to Lactobacillus, the foul-smelling sour soup contained more Pediococcus spp., Caproiciproducens spp., and Clostridium-sensu-stricto 12 spp. (relative abundance >1%) than the normal sour soup. A total of 51 aroma compounds were detected by gas chromatography-mass spectrometry(GC-IMS), including 25 esters, 8 terpenes, 8 alcohols, 3 sulfur compounds, 2 acids, 2 ketones, 1 pyrazine, 1 monoterpene and 1 aldehyde. According to the relative odour active value (ROAV) calculation, 51 important flavour-contributing substances and 7 flavour-coordinating substances were determined. The esters with the highest relative percentages and ROAV values provided the pleasant flavour of the sour soup. In the foul-smelling sour soup, the ROAV values of 1,8-cineole, isobutyl acetate, ethyl butanoate, ethyl octanoate-M, and ethyl hexanoate-M decreased, while those of diallyl disulfide-M and diallyl disulfide-D, which were probably responsible for the foul flavour, increased. Through Pearson correlation analysis, the odour production of the foul-smelling soup was determined to be related to Pediococcus spp., Caproiciproducens spp., Clostridiumsensu_stricto_12 spp., Oscillibacter spp., Bacteroides spp., Fibaculaceae_unclassified spp., Acinetobacter spp. and Halomonas spp.

The molecular basis of thioalcohol production in human body odour

Body odour is a characteristic trait of Homo sapiens, however its role in human behaviour and evolution is poorly understood. Remarkably, body odour is linked to the presence of a few species of commensal microbes. Herein we discover a bacterial enzyme, limited to odour-forming staphylococci that are able to cleave odourless precursors of thioalcohols, the most pungent components of body odour. We demonstrated using phylogenetics, biochemistry and structural biology that this cysteine-thiol lyase (C-T lyase) is a PLP-dependent enzyme that moved horizontally into a unique monophyletic group of odour-forming staphylococci about 60 million years ago, and has subsequently tailored its enzymatic function to human-derived thioalcohol precursors. Significantly, transfer of this enzyme alone to non-odour producing staphylococci confers odour production, demonstrating that this C-T lyase is both necessary and sufficient for thioalcohol formation. The structure of the C-T lyase compared to that of other related enzymes reveals how the adaptation to thioalcohol precursors has evolved through changes in the binding site to create a constrained hydrophobic pocket that is selective for branched aliphatic thioalcohol ligands. The ancestral acquisition of this enzyme, and the subsequent evolution of the specificity for thioalcohol precursors implies that body odour production in humans is an ancient process.