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PubMed2006

Evaluation of gas removal and bacterial community diversity in a biofilter developed to treat composting exhaust gases.

The performance of a new, but simply constructed, biofilter system, developed to purify composting exhaust air, was evaluated. The biofilter was packed with mature compost mixed with activated carbon and sludge sourced from a wastewater treatment plant. An alternating air flow system and a bioaerosol reduction device were designed to prevent pressure drop and reduce bioaerosol release. Experimental results demonstrated that satisfactory removal efficiencies of nitrogen-containing compounds, sulfur-containing compounds, fatty acids, total hydrocarbon and odor were achieved at an empty bed retention time (EBRT) of 30s. No significant acidification or alkalinity in the biofilter was observed, and the system was characterized by a small pressure drop and a low level of bioaerosol emission. Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH) techniques were used to uncover the changes in the bacterial community of the biofilter during the deodorization processes. A minimum of 16 bands were observed in the DGGE profile. Phylogenetic analysis revealed the phylum of Proteobacteria to be predominant, followed by Actinobacteria, Bacteroidetes, and Firmicutes, in descending order. However, the occurrence and predominance of specific bacterial species varied with the environmental conditions of the biofilter. Our results demonstrate - from both an engineering and biological point of view - the feasibility of the biofilter system described herein in purifying the gases derived from composting food waste.

Air Pollutants↗
PubMed1999

Biodesulfurization.

Microbial sulfur-specific transformations have been identified that selectively desulfurize organic sulfur compounds in fossil fuels. Recent discoveries related to biodesulfurization mechanisms may lead to commercial applications of biodesulfurization through engineering recombinant strains for over-expression of biodesulfurization genes, removal of end product repression, and/or by combining relevant industrial and environmental traits with improvements in bioprocess design.

Bacteria↗
PubMed2003

Substrate preferences in biodesulfurization of diesel range fuels by Rhodococcus sp. strain ECRD-1.

The range of sulfur compounds in fuel oil and the substrate range and preference of the biocatalytic system determine the maximum extent to which sulfur can be removed by biodesulfurization. We show that the biodesulfurization apparatus in Rhodococcus sp. strain ECRD-1 is able to attack all isomers of dibenzothiophene including those with at least four pendant carbons, with a slight preference for those substituted in the alpha-position. With somewhat less avidity, this apparatus is also able to attack substituted benzothiophenes with between two and seven pendant carbons. Some compounds containing sulfidic sulfur are also susceptible to desulfurization, although we have not yet been able to determine their molecular identities.

Biodegradation, Environmental↗
PubMed1964

ANAEROBIC GROWTH OF FUSARIUM OXYSPORUM.

Gunner, H. B. (Cornell University, Ithaca, N.Y.), and M. Alexander. Anaerobic growth of Fusarium oxysporum. J. Bacteriol. 87:1309-1316. 1964.-Fusarium oxysporum, an alleged obligate aerobe, was found to be capable of growth in the absence of molecular oxygen, provided the medium contained yeast extract, MnO(2), nitrate, selenite, or ferric ions. The active substance in yeast extract was not identified. The fungus possessed hydrogenase, and was capable of utilizing H(2). Under anaerobic conditions, the fungus effected the reduction of nitrate, ceric, ferric, selenite, and tellurite ions, as well as the reduction of several inorganic sulfur compounds and indicators having positive oxidation-reduction potentials. The products of anaerobic nitrate-dependent growth were ethanol, CO(2), acetic acid, and ammonia. Possible explanations for the apparent inability of obligate aerobes to grow in the absence of O(2) are discussed.

Ammonia↗
PubMed2000

Confirmation of Thiobacillus denitrificans as a species of the genus Thiobacillus, in the beta-subclass of the Proteobacteria, with strain NCIMB 9548 as the type strain.

Thiobacillus denitrificans is physiologically similar to the type species of the genus Thiobacillus, Thiobacillus Thioparus, and both are located in the beta-subclass of the Proteobacteria. T. denitrificans is distinguished from all other Thiobacillus species by its ability to grow as a facultatively anaerobic chemolithotroph, coupling the oxidation of inorganic sulfur compounds to the reduction of nitrate, nitrite and other oxidized nitrogen compounds to dinitrogen. A definitive description of this species is provided and strain NCIMB 9548T is designated as the type strain of the species, thereby correcting an earlier error in the literature.

Base Composition↗
PubMedDate not supplied

A Cochrane systematic review finds tongue scrapers have short-term efficacy in controlling halitosis.

The Cochrane systematic review promotes evidence-based outcome studies. This review was conducted to determine reliable evidence concerning the effectiveness of tongue scraping or cleaning, compared with other interventions for controlling halitosis. A competent search strategy was developed and used across several databases--including the Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and Google Scholar--to identify randomized controlled trials that compared different methods of tongue cleaning to reduce mouth odor in adults with halitosis. Methodological quality of studies was assessed based on criteria defined by the Cochrane Collaboration. Clinical outcome (expressed in terms of a reduction in mouth odor in adults with halitosis) was examined. The review included two trials involving a total of 40 participants. Based on the independent data from these two trials, the tongue cleaner or the tongue scraper demonstrated a statistically significant difference in reducing levels of volatile sulfur compounds (VSCs) when compared with the toothbrush. The findings indicate a small but statistically significant difference in reduction of VSC levels when tongue scrapers or cleaners, rather than toothbrushes, are used to reduce halitosis in adults.

Adult↗
PubMed2005

Sulfate-dependent repression of genes that function in organosulfur metabolism in Bacillus subtilis requires Spx.

Oxidative stress in Bacillus subtilis results in the accumulation of Spx protein, which exerts both positive and negative transcriptional control over a genome-wide scale through its interaction with the RNA polymerase alpha subunit. Previous microarray transcriptome studies uncovered a unique class of genes that are controlled by Spx-RNA polymerase interaction under normal growth conditions that do not promote Spx overproduction. These genes were repressed by Spx when sulfate was present as a sole sulfur source. The genes include those of the ytmI, yxeI, and ssu operons, which encode products resembling proteins that function in the uptake and desulfurization of organic sulfur compounds. Primer extension and analysis of operon-lacZ fusion expression revealed that the operons are repressed by sulfate and cysteine; however, Spx functioned only in sulfate-dependent repression. Both the ytmI operon and the divergently transcribed ytlI, encoding a LysR-type regulator that positively controls ytmI operon transcription, are repressed by Spx in sulfate-containing media. The CXXC motif of Spx, which is necessary for redox sensitive control of Spx activity in response to oxidative stress, is not required for sulfate-dependent repression. The yxeL-lacZ and ssu-lacZ fusions were also repressed in an Spx-dependent manner in media containing sulfate as the sole sulfur source. This work uncovers a new role for Spx in the control of sulfur metabolism in a gram-positive bacterium under nonstressful growth conditions.

Bacillus subtilis↗
PubMed2007

Transcriptional analysis of L-methionine catabolism in Brevibacterium linens ATCC9175.

The expression of genes possibly involved in L-methionine and lactate catabolic pathways were performed in Brevibacterium linens (ATCC9175) in the presence or absence of added L-methionine. The expression of 27 genes of 39 selected genes differed significantly in L-methionine-enriched cultures. The expression of the gene encoding L-methionine gamma-lyase (MGL) is high in L-methionine-enriched cultures and is accompanied by a dramatic increase in volatile sulfur compounds (VSC) biosynthesis. Several genes encoding alpha-ketoacid dehydrogenase and one gene encoding an acetolactate synthase were also up-regulated by L-methionine, and are probably involved in the catabolism of alpha-ketobutyrate, the primary degradation product of L-methionine to methanethiol. Gene expression profiles together with biochemical data were used to propose catabolic pathways for L-methionine in B. linens and their possible regulation by L-methionine.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2005

Halitosis: a review.

Halitosis, or bad breath, is caused by mainly volatile sulfur compounds (VSC) as a result of bacterial breakdown of protein and can be quantitatively and qualitatively measured in the expired oral breath. In eight to ninety percent of cases, halitosis originates in the mouth due to inadequate plaque control, periodontal disease, dry mouth, faulty restorations, and in particular due to excessive bacterial growth on the posterior third of the dorsal surface of the tongue. In the remaining ten to twenty percent of cases, bad breath is caused by systemic disorders such as hepatic, pancreatic and nephritic insufficiencies, trimethylaminuria, upper and lower respiratory tract infection, medication and cases where gastric content may generate oral malodour. The methods of detecting or diagnosing halitosis are organoleptic or human sense of smell, sulfide monitoring and gas chromatography. All of these methods have limitations and disadvantages. A more accurate, analytical system which will be able to precisely detect the volatile compounds in the expired air and correlate the results to a specific cause is not yet available. Dental professionals require a good knowledge on the subject of bad breath in order to feel secure about counseling and managing patients suffering from this condition. The management of halitosis involves maintenance of plaque control, elimination of active periodontal disease and cleaning the tongue on a routine basis. Oral rinsing with a mouthwash could be indicated in some instances, as a temporary measure.

Bacteria, Anaerobic↗
PubMed1994

[Halitosis (fetor ex ore). A review].

About 15% of the Dutch population has, in a more or lesser degree, complaints about bad breath. This is caused particularly by the anaerobic metabolism of a number of oral microorganisms, in which putrefaction occurs and volatile sulfur compounds will be formed. Some of these compounds are also possibly involved in the pathogenesis of periodontitis. A good oral hygiene is of primary importance to prevent halitosis and to reduce bad breath. Antiseptic mouth-waters can be helpful in the reduction of the bacterial metabolism. In addition, stimulation of the salivary secretion has a dual favourable effect, firstly because of its antimicrobial salivary proteins, and secondly by reduction of the retention of nutrients in the oral cavity.

Bacteria, Anaerobic↗
PubMed2001

Assessment of newly developed tongue sulfide probe for detecting oral malodor.

AIM: The present study examined the relationship between sulfide levels on tongue dorsum surfaces (pS levels) and oral malodor. METHOD: The pS levels of 20 systemically healthy volunteers were evaluated using an industrial device equipped with a newly-developed tongue sulfide probe. The pS levels on 3 parts of the tongue--anterior, middle and posterior along the median groove of the tongue dorsum--were determined for each subject. RESULTS: The device reported the pS level in a digital score ranging from 0.0 (< 10(-7) M of sulfide) to 5.0 (> or = 10(-2) M of sulfide) in increments of 0.5. Oral malodor was assessed by measuring the level of volatile sulfur compounds in mouth air, as well as by the organoleptic method. The pS levels were 0.03 +/- 0.11, 0.20 +/- 0.41 and 0.88 +/- 0.76 for the anterior, middle and posterior parts, respectively. This difference was significant (p<0.001). Both oral malodor measurements showed significant correlation (p<0.05) with the pS levels of middle and posterior parts of tongue. CONCLUSION: It was concluded that the tongue sulfide probe might be useful in management of subjects with oral malodor.

Adult↗
PubMed2001

Oral malodor control afforded through the use of sodium bicarbonate-containing chewing gum.

Published research indicates that regular use of toothpaste containing sodium bicarbonate is effective in reducing volatile sulfur compounds (VSCs) and oral malodor. Gaffar initially reported on the use of sodium bicarbonate as an agent to affect VSCs, indicating that sodium bicarbonate had the potential to alter the VSCs to nonvolatile compounds. Chewing gum would also be suspected of providing benefits in controlling oral malodor through its claimed ability to mechanically aid in the removal of dental plaque. Based on the length of chewing time, the opportunity exists for chewing gum to reach places in the mouth that might be missed during brushing. This activity could contribute to reductions in the amount of viable plaque mass that could produce VSCs.

Adult↗
PubMed2003

In vitro efficacy of Colgate Total advanced fresh.

Generally, clinical studies using organoleptic judges, gas chromatography, or a sulfide monitor have been employed in the assessment of treatments for the control of oral malodor. However, these studies can be expensive and time consuming. Also, for agents whose safety has not been proven, these methods are not appropriate. Therefore, in vitro assessment is a critical step toward developing a new technology or implementing changes to an existing formula. The in vitro methods employed in this study combined basic microbiology methods, such as growth inhibition and zone of inhibition experiments. In addition, a newly developed, in vitro, volatile sulfur compounds (VSC) experiment that combined the essential elements of zone of inhibition, head space analysis, and dynamic flow cell techniques was also employed. The in vitro VSC method has been validated using technologies clinically proven to control oral malodor. All in vitro experiments have demonstrated that Colgate Total Advanced Fresh toothpaste has efficacy similar to that of the original Colgate Total toothpaste and that both variants showed superior efficacy to the control toothpaste. These results have been corroborated by clinical study results.

Actinomyces↗
PubMed2002

Effect of dietary sorghum cultivars on the storage stability of broiler breast and thigh meat.

A total of 450 1-d-old male broiler chicks were fed a corn-soy-flax meal-based diet (control), two cultivars of sorghum--Ruby Red (low tannin content) and Valpo Red (high tannin content)--were used at 10% level. Birds were slaughtered at the end of 42-d feeding trial. Boneless, skinless breast and thigh muscles were separated and ground to make patties. Half of the breast and thigh meat patties were individually packaged in zipper bags, and 2-TBA-reactive substances (TBARS) and colors of the patties were determined after 0 and 7 d of storage at 4 C. The other half was cooked and vacuum-packaged. The vacuum-packaged patties were used to determine time-dependent volatile production and oxidative change during 12-h holding time before analyses. Thigh meat from broilers fed the Valpo Red cultivar produced lower TBARS than that from control at Day 0. The amounts of aldehydes and sulfur compounds of cooked breast meats were lower from chickens fed the Valpo Red cultivar than those fed the control or Ruby Red cultivar. Dietary Valpo Red cultivar improved the oxidative stability of breast meat 8 and 12 h after cooking. Dietary sorghum slightly improved the color a* stability of raw thigh meat patties. This result indicated that feeding sorghum to broilers could improve some measures of the storage stability of broiler meat, but sorghum with high tannin content was more effective than that with low tannin content.

Aldehydes↗
PubMed2006

Effect of high-pressure-moderate-temperature processing on the volatile profile of milk.

The effects of high hydrostatic pressure on volatile generation in milk were investigated in this study. Raw milk samples were treated under different pressures (482, 586, and 620 MPa), temperatures (25 and 60 degrees C), and holding times (1, 3, and 5 min). Samples submitted to heat treatments alone (25, 60, and 80 degrees C for 1, 3, and 5 min) were used for comparison. Trace volatile sulfur compounds were analyzed using solid-phase microextraction (SPME) and gas chromatography (GC) with pulsed-flame photometric detection (PFPD), whereas the rest of the volatile compounds were analyzed using SPME-GC with flame ionization detection (FID). Multivariate analysis of variance (MANOVA) and principal component analysis (PCA) were used to study the effect of pressure, temperature, and time on volatile generation. Relative concentration increases of 27 selected volatile compounds were compared to an untreated sample. It was found that pressure, temperature, and time, as well as their interactions, all had significant effects (P < 0.001) on volatile generation in milk. Pressure and time effects were significant at 60 degrees C, whereas their effects were almost negligible at 25 degrees C. The PCA plot indicated that the volatile generation of pressure-heated samples at 60 degrees C was different from that of heated-alone samples. Heat treatment tended to promote the formation of methanethiol, hydrogen sulfide, methyl ketones, and aldehydes, whereas high-pressure treatment favored the formation of hydrogen sulfide and aldehydes.

Animals↗
PubMed2004

Clinical assessment of oral malodor by the electronic nose system.

A recently developed electronic nose has not yet been clinically applied to evaluations of oral malodor. This investigation sought to determine whether an electronic nose could clinically assess oral malodor. Twenty-nine healthy adults and 49 patients were assessed by results of an actual organoleptic test, a score representing malodor strength with an electronic nose in "top-note" mode (top-note score), and measurements of volatile sulfur compound (VSC) concentrations. The correlation coefficient between top-note and actual organoleptic scores (r = 0.71) was comparable with the log VSC and actual organoleptic scores (r = 0.63). However, the area under the receiver-operating characteristic plots for top-note score was significantly larger than that for log VSC. In logistic regression analyses with top-note score as a dependent variable, probing depth, tongue coating, and plaque control record each had independent associations. Our findings suggest that the top-note score from an electronic nose examination may be useful for the clinical evaluation of oral malodor.

Adult↗
PubMed2005

Relationship between the SF-36 questionnaire and patient's satisfaction following halitosis therapy.

OBJECTIVE: To assess the health-related quality of life (HRQOL) of patients complaining of halitosis at their first visit and at a later time when their complaint had diminished following therapy, using a self-administered questionnaire, the Medical Outcome Study Short Form-36 (SF-36). The aim of this study was to examine the relationship between HRQOL of patients before and after self-reported disappearance of their complaint following oral hygiene improvements for halitosis. SUBJECTS AND METHODS: Seventy patients of our special clinic for halitosis served as subjects. At the first visit, each completed the SF-36 before determination of volatile sulfur compound (VSC) concentration in mouth air. After excluding dropouts, the same measurements were performed for subjects whose self-reported complaint had disappeared following oral hygiene therapy. RESULTS AND DISCUSSION: At the initial visit, SF-36 scale scores for general health, vitality, social functioning, role-emotion, and mental health were significantly lower when compared with the national averages in Japan. For subjects with self-reported disappearance of complaint, only social functioning rose significantly among SF-36 scores at the end of the study. These results suggest that an awareness of improvement in social life could be related to patient's satisfaction with halitosis oral hygiene therapy.

Breath Tests↗
PubMed2005

Evaluation of oral and nasal halitosis parameters in patients with repaired cleft lip and/or palate.

OBJECTIVE: The objective of this study was to investigate the relationship between halitosis parameters in patients with and without cleft lip and/or palate. STUDY DESIGN: Forty-two subjects were examined. They were divided into group I, postgraduate students of Bauru Dental School (FOB); and group II, individuals with repaired cleft lip and/or palate. The concentration of volatile sulfur compounds (VSC) was assessed with a portable sulfide monitor and the values were correlated to the salivary flow rate and weight of tongue coating. RESULTS: There was a relationship between the presence of tongue coating and VSC levels, as well as between salivary flow rate and VSC levels in group II. The same group also revealed a significant correlation between weight of tongue coating and salivary flow rate. There were no significant differences between groups as regards the Halimeter oral measurement. CONCLUSIONS: Individuals with repaired cleft lip and/or palate can have the same VSC levels as subjects without clefts.

Adult↗