Changes in free fatty acids of awamori during aging

The fatty acid components of awamori during aging were as follows. The total amount of volatile acids calculated as acetic acid ranged from 20 to 140 mg/l, the main acid was acetic acid, and the proportion of acetic acid to total acids ranged from 35 to 80 per cent. The main acids other than acetic acid were propionic acid and i-butyic acid. Differences were observed in fatty acid constituents between awamori and other alcoholic beverages.Certain components tended to increase during maturation in kame (porous earth-enware pots): acetic acid, i-butyric acid, i-valeric acid, valeric acid, capric acid, lauric acid, myristic acid and total fatty acids. Others, however, showed no distinct changes: propionic acid, butyric acid, caproic acid, caprylic acid, palmitic acid, stearic acid, oleic acid and linoleic acid.During maturation in non-porous containers (stainless-steel or glass-linked tanks), on the other hand, caprylic acid, capric acid, lauric acid and myristic acid components tended to increase, while no distinct changes however were shown by acetic acid, propionic acid, i-butyric, butyric acid, i-valeric acid, valeric acid, caproic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and total fatty acids.     

Growth and end-product formation in fermenter cultures of Brochothrix thermosphacta ATCC 11509T and two psychrotrophic Lactobacillus spp. in different gaseous atmospheres

The effects of different gaseous atmospheres were determined on the maximum specific growth rate (μ_max) and end-product formation by Brochothrix thermosphacta ATCC 11509^T, Lactobacillus viridescens SMRICC 174 and Lactobacillus sp. SMRICC 173 (homofermentative). The highest μ_max-values for Lact. viridescens (0.47/h) and Broc. thermosphacta (0.49/h) were obtained in air. Under anaerobic conditions μ_max was reduced, an atmosphere containing CO₂ alone giving the greatest reduction. Lactobacillus sp. 173 did not grow in air or N₂. Aerobic growth was obtained by adding peroxidase while anaerobic growth occurred in the presence of 5–20% CO₂. Carbon dioxide alone reduced the growth rate. All test organisms produced mainly lactic acid anaerobically. Lactobacillus viridescens also produced ethanol while Broc. thermosphacta produced small amounts of ethanol and formic acid. With O₂ present, the number of end-products increased for all organisms. Lactobacillus sp. 173 produced small amounts of acetic acid and acetoin together with lactic acid. Oxygen induced acetic acid production in Lact. viridescens and Broc. thermosphacta . Aerobically, Broc. thermosphacta also produced a large amount of acetoin and smaller amounts of 2,3-butanediol, iso -valeric acid and iso -butyric acid. The production of lactic acid by Broc. thermosphacta was completely prevented under strictly aerobic conditions. All test organisms consumed O₂ during aerobic growth. Hydrogen peroxide was produced by Lact. viridescens and Lactobacillus sp. 173.     

Characterization of Bacteroides Species Isolated From Soft Tissue Infections in Cats

A total of 77 strains of Gram negative anaerobes belonging to the genus Bacteroides and isolated from 60 subcutaneous abscesses and 10 cases of pyothorax in cats, have been examined morphologically and biochemically. Colony pigmentation, gas chromatography and biochemical analysis placed them into two major categories-those which produced pigmented colonies (Group 1) and those which failed to produce pigmented colonies after 14 d on laked blood agar (Group 2). All 29 strains in Group 1 produced acetic, propionic, isobutyric, butyric, isovaleric and succinic acids but failed to ferment carbohydrates, and were classified as B. asaccharolyticus. All organisms in Group 2 produced acetic, propionic, isobutyric, isovaleric and succinic acids and were divided into four categories based on indole production and bile tolerance. Designation to species was then decided on the basis of phenylacetic acid production and sugar fermentation tests. This sequence of analysis of results enabled confident speciation of some groups of these organisms despite some biochemical variation of the cat strains when compared to human type strains.     

Precursors of the major end products of aerobic metabolism of Brochothrix thermosphacta

To further our understanding of off-odour production by Brochothrix thermosphacta , the nature and origins of its end products have been compared during aerobic growth in complex and in minimal, defined medium. In complex medium glucose is the major precursor of acetoin and acetic acid but alanine may be an additional minor source. Iso butyric, iso valeric (3-methylbutyric) and 2-methylbutyric acids are derived exclusively from valine, leucine and iso leucine, respectively. In minimal defined medium although the same end products are produced they are all derived from glucose.     

Amino acid utilization patterns in clostridial taxonomy

The polyamide layer technique for the chromatographic separation of dimethylaminonaphthalene sulphonyl amino acids has been adapted to the qualitative analysis of amino acids in media before and after the growth of micro-organisms. The method has been used to study the amino acids metabolized by cultures of proteolytic clostridia growing in a medium consisting of an acid hydrolysate of casein as a source of amino acids and small amounts of yeast extract and trypticase as sources of growth factors. The chromatograms of the media after growth showed which amino acids were used and which new amino acids were produced. Clostridium botulinum type F (proteolytic), C. ghoni, C. mangenoti and C. putrificum were found to reduce proline to 5-aminovaleric acid and to produce 2-aminobutyric acid, properties they shared with C. sporogenes and C. sticklandii. C. botulinum type G and C. subterminale used glycine, lysine, serine, and arginine but in contrast to C. sticklandii they neither reduced proline to 5-aminovaleric acid nor produced 2-aminobutyric acid. Both organisms oxidized phenylalanine, tyrosine and tryptophan to phenylacetic acid, p-hydroxyphenyl acetic acid and indole acetic acid respectively. C. lituseburense and C. scatologenes used serine, threonine and arginine and produced 2-amino butyric acid and ornithine. C. lentoputrescens, C. limosum and C. malenomenatum resembled C. tetanomorphum by using glutamic acid and tyrosine. The chromatograms always showed the physiological group to which an organism belonged and in some cases were characteristic of the species.Abbreviations Abu 2-aminobutyric acid - Ava 5-aminovaleric acid - DNS 1-dimethyaminonaphthalene-5-sulphonyl - DNS-Cl the sulphonyl chloride - DNS-NH₂ the sulphonamide - DNS-OH the sulphonic acid - VFA steam volatile fatty acid - u unknown     

Effects of butyric and acetic acids on acetone-butanol formation by Clostridium acetobutylicum

The actions of butyric and acetic acids on acetone-butanol fermentation are investigated. Production of butyric and acetic acids are controlled by the extracellular concentrations of both acids: acetic acid added to the medium inhibits its own formation but has no effect on butyric acid formation, and added butyric acid inhibits its own formation but not that of acetic acid. The ratio of end metabolites depends upon acetic and butyric acid quantities excreted during the fermentation. In contrast to acetic acid, which specifically increases acetone formation, butyric acid increases both acetone and butanol formations. Acetate and butyrate kinase activities were also examined. Both increase at the start of fermentation and decrease when solvents appear in the medium. Coenzyme A transferase activity is weak in the acidogenic phase and markedly increases in the solvent phase. Acetic and butyric acids appear to be co-substrates. On the basis of these results, a mechanism of acetic and butyric acid pathways, coupled to solvent formation by C. acetobutylicum glucose fermentation is proposed.     

Antimould activity of sourdough lactic acid bacteria: identification of a mixture of organic acids produced by Lactobacillus sanfrancisco CB1

Sourdough lactic acid bacteria, cultivated in wheat flour hydrolysate, produced antimould compounds. The antimould activity varied greatly among the strains and was mainly detected within obligately heterofermentative Lactobacillus spp. Among these, Lb. sanfrancisco CB1 had the largest spectrum. It inhibited moulds related to bread spoilage such as Fusarium, Penicillium, Aspergillus and Monilia. A mixture of acetic, caproic, formic, propionic, butyric and n-valeric acids, acting in a synergistic way, was responsible for the antimould activity. Caproic acid played a key role in inhibiting mould growth. Received: 20 January 1998 / Received revision: 17 April 1998 / Accepted: 27 April 1998     

Production of butanol by Clostridium puniceum in batch and continuous culture

Summary The pink-pigmented, amylolytic and pectinolytic bacterium Clostridium puniceum in anaerobic batch culture at pH 5.5 and 25–30°C produced butan-1-ol as the major product of fermentation of glucose or starch. The alcohol was formed throughout the exponential phase of growth and surprisingly little acetone was simultaneously produced. Furthermore, acetic and butyric acids were only accumulated in low concentrations, and under optimal conditions were completely re-utilised before the fermentation ceased. Thus, in a minimal medium containing 4% w/v glucose as sole source of carbon and energy, after 65 h at 25°C, pH 5.5 all of the glucose had been consumed to yield (g product/100 g glucose utilised) butanol 32, acetone 3 and ethanol 2. Butanol was again the major product of glucose fermentation during phosphate-limited chemostat culture wherein, although the organism eventually lost its capacity to sporulate and to synthesize granulose, production of butanol continued for at least 100 volume changes. Under no growth condition was the organism capable of producing more than 13.3 g l^-1 of butanol. At pH 5.5, growth on pectin was slow and yielded a markedly lesser biomass concentration than when growth was on glucose or starch; acetic acid was the major fermentation product with lower concentrations of methanol, acetone, butanol and butyric acid. At pH 7, growth on all substrates produced virtually no solvents but high concentrations of both acetic and butyric acids.     

Solvent production byClostridium pasteurianum in media of high sugar content

Summary The fermentation end products ofClostridium pasteurianum ATCC 6013 are normally acetic and butyric acids. When grown in media of high sugar content however, significant quantities of solvents (acetone, butanol and ethanol) were produced. Solvent production was not stimulated by added acetic and butyric acids, nor was the effect due to a low water activity of the mediumper se.     

Production of carboxylic acids from hydrolyzed corn meal by immobilized cell fermentation in a fibrous-bed bioreactor

Corn meal hydrolyzed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via anaerobic fermentations. In this study, corn meal, containing 75% (w/w) starch, 20% (w/w) fibers, and 1.5% (w/w) protein, was first hydrolyzed using amylases at 60 degrees C. The hydrolysis yielded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactococcus lactis and Clostridium formicoaceticum was used to produce acetic acid from glucose. Propionibacterium acidipropionici was used for propionic acid fermentation, and Clostridium tyrobutylicum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirred-tank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37 degrees C and 7.6, respectively, for acetic acid fermentation, 32 degrees C and 6.0, respectively, for propionic acid fermentation, and 37 degrees C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(1 h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(1 h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(1 h). These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fiber present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized cell bioreactor systems. It is concluded that the FBB technology is suitable for producing value-added biochemicals directly from agricultural residues or commodities such as corn meal.     

Carbohydrate-Free Media for Crithidia

SYNOPSIS. The insect trypanosomatid Crithidia fasciculata grew well at pH 3.8–6.3 in defined carbohydrate-free media containing arginine (an essential amino acid) + proline + glutamic acid as substrates; glycerol was effective by itself. Precipitation of hemin in the acid media did not hinder growth. Further addition of succinic acid permitted growth matching that with carbohydrate. At pH 6.9–7.5 growth in this medium without carbohydrate with the aforementioned non-fermentable substrates was slight; added carbohydrate (as sucrose or sorbitol) permitted good growth. Utilization of non-carbohydrate substrates may contribute to Crithidia 's ability (and presumably to that of pathogenic trypanosomatids as well) to multiply in the insect gut and to the ability of some Trypanosoma species to multiply in the insect hemocoel and salivary gland.     

Effect of Organic Acids on Shrimp Pathogen, <Emphasis Type="Italic">Vibrio harveyi</Emphasis>

Shrimp farming accounts for more than 40% of the world shrimp production. Luminous vibriosis is a shrimp disease that causes major economic losses in the shrimp industry as a result of massive shrimp kills due to infection. Some farms in the South Asia use antibiotics to control Vibrio harveyi, a responsible pathogen for luminous vibriosis. However, the antibiotic-resistant strain was found recently in many shrimp farms, which makes it necessary to develop alternative pathogen control methods. Short-chain fatty acids are metabolic products of organisms, and they have been used as food preservatives for a long time. Organic acids are also commonly added in feeds in animal husbandry, but not in aquaculture. In this study, growth inhibitory effects of short-chain fatty acids, namely formic acid, acetic acid, propionic acid, and butyric acid, on V. harveyi were investigated. Among four acids, formic acid showed the strongest inhibitory effect followed by acetic acid, propionic acid, and butyric acid. The minimum inhibitory concentration (MIC) of 0.035% formic acid suppressed growth of V. harveyi. The major inhibitory mechanism seems to be the pH effect of organic acids. The effective concentration 50 (EC₅₀) values at 96 h inoculation for all organic acids were determined to be 0.023, 0.041, 0.03, and 0.066% for formic, acetic, propionic, and butyric acid, respectively. The laboratory study results are encouraging to formulate shrimp feeds with organic acids to control vibrio infection in shrimp aquaculture farms.     

有机酸胁迫下厌氧污泥产氢效果

乙酸、丙酸、乳酸及丁酸是厌氧发酵产氢过程中4种主要的液相末端发酵产物,其积累对产氢过程有一定的抑制作用。实验利用多种有机酸胁迫提高污泥的酸耐受能力,并以污泥中脱氢酶活性为生化指标,对不同浓度酸胁迫下厌氧污泥活性变化进行了研究。通过对胁迫后污泥产氢量及末端产物进行对比。结果表明,酸胁迫后污泥产氢量有一定增加,其中乙酸和丁酸胁迫效果最好,较对照组提高了近一倍;末端产物分析研究表明,不同的有机酸胁迫后,其产量在发酵过程中都有一定的增加,而乙酸含量在酸胁迫后都有不同程度的提高。     

Amino acid fermentation byBacteroides melaninogenicus

Each of four strains ofBacteroides melaninogenicus grew well in a trypticaseyeast extract medium, without carbohydrate. Addition of glucose did not increase growth, and the sugar was fermented to only a limited extent. However, growth decreased when the trypticase concentration of the medium was reduced. These observations suggest that amino acid fermentation is of major importance in the energy metabolism ofB. melaninogenicus. Acetic, butyric and isovaleric acids were produced by all four strains. Two of the strains also formed propionic and isobutyric acids. Experiments using media containing either labeled glucose or labeled protein indicated that these acids are primarily derived from the proteinaceous substrates in the medium, rather than from glucose, indicating that amino acid fermentation byB. melaninogenicus is not subject to glucose repression. Resting-cell suspensions ofB. melaninogenicus possessed a limited ability to ferment free acids, as judged by the liberation of ammonia. However the organisms readily fermented amino acids when present as peptides, suggesting that peptides are more readily transported into the cell. Three of the 4 strains studied grew well when incubated under an atmosphere containing 2 to 4 % oxygen in cultures possessing a high surface to volume ratio. Hence not all strains ofB. melaninogenicus can be considered strict anaerobes.This investigation was supported in part by grant DE-02847 from the National Institute of Dental Research, and in part by a grant from the Colgate-Palmolive Co.     

A note on hydrolysis of tributyrin by Branhamella and Neisseria

Sixty-three strains of Branhamella and Neisseria were tested by two methods for their ability to hydrolyse glycerol tributyrate. After the conventional plate test, gas liquid chromatographical (GLC) analysis of the agar medium was carried out to detect the hydrolysis product, butyric acid, and other volatile fatty acids. All strains of Branhamella catarrhalis, Neisseria caviae, N. cuniculi and N. ovis but no other Neisseria spp. gave positive results with the conventional test. With GLC, however, most strains of Branhamella and Neisseria were shown to liberate butyric acid. In addition, some strains liberated acetic and isovaleric acids. Greater amounts of butyric acid were produced by clinical strains, in particular B. catarrhalis , compared with reference strains. It was concluded that the conventional plate test for tributyrin hydrolysis differentiates B. catarrhalis, N. caviae, N. cuniculi and N. ovis from other Neisseria.     

A note on hydrolysis of tributyrin by Branhamella and Neisseria

Sixty-three strains of Branhamella and Neisseria were tested by two methods for their ability to hydrolyse glycerol tributyrate. After the conventional plate test, gas liquid chromatographical (GLC) analysis of the agar medium was carried out to detect the hydrolysis product, butyric acid, and other volatile fatty acids. All strains of Branhamella catarrhalis, Neisseria caviae, N. cuniculi and N. ovis but no other Neisseria spp. gave positive results with the conventional test. With GLC, however, most strains of Branhamella and Neisseria were shown to liberate butyric acid. In addition, some strains liberated acetic and isovaleric acids. Greater amounts of butyric acid were produced by clinical strains, in particular B. catarrhalis, compared with reference strains. It was concluded that the conventional plate test for tributyrin hydrolysis differentiates B. catarrhalis, N. caviae, N. cuniculi and N. ovis from other Neisseria.     

The fermentation of lactulose by colonic bacteria

Sixty-four strains of intestinal bacteria were cultured under anaerobic conditions in lactulose-containing media to assess their ability to ferment lactulose. Some organisms were unable to metabolize the disaccharide, while others, e.g. clostridia and lactobacilli, metabolized lactulose extensively. Quantitative analyses of the fermentation products indicated that the major non-gaseous metabolites were acetic, lactic and butyric acids. Hydrogen and carbon dioxide were the only gases detected. Fermentation products were estimated for selected species throughout their growth cycles. The products of fermentation of lactulose by stool cultures varied with incubation conditions such as pH, but correlated well with those produced by pure cultures. These results are discussed in relation to the therapeutic uses of lactulose.     

The role of acids on the production of acetone and butanol by Clostridium acetobutylicum

Summary The production of solvent by Clostridium acetobutylicum was studied, using fed-batch fermentations. Different specific rates of carbohydrate utilisation were obtained by variations in feeding rates of sugar. At slow catabolic rates of sugar, addition of acetic acid or butyric acid, alone or together, increased the rate of the metabolic transition by a factor 10 to 20, the amount of solvents by a factor 6 and the percentage of fermented glucose to solvents by a factor 3. The same results were obtained with both glucose and xylose fermentations. Depending on the rates of growth, butanol production began at acid levels of 3–4 g·l^-1 for fast metabolism and at acid levels of 8–10 g·l^-1 for slow metabolism. Associated with slow metabolism, reassimilation of acids required values as high as 6.5 g·l^-1 of acetic acid and 7.5 g·l^-1 of butyric acid. At a high rate of metabolism, acetic and butyric acids were reassimilated at concentrations of 4.5 g·l^-1.     

Assessment of toxicity of volatile fatty acids to Photobacterium phosphoreum

The toxicity of four volatile fatty acids (VFAs) as anaerobic digestion (AD) intermediates was investigated at pH 7. Photobacterium phosphoreum T3 was used as an indicator organism. Binary, ternary and mixtures of AD intermediates were designated by letters A (acetic acid + propionic acid), B (acetic acid + butyric acid), C (acetic acid + ethanol), D (propionic acid + butyric acid), E (propionic acid + ethanol), F (butyric acid + ethanol), G (acetic acid + propionic acid + butyric acid), H (acetic acid + propionic acid + ethanol), I (acetic acid + butyric acid+ ethanol), J (propionic acid + butyric acid + ethanol) and K (acetic acid + propionic acid + butyric acid + ethanol) to assess the toxicity through equitoxic mixing ratio method. The IC₅₀ values of acetic acid, propionic acid, butyric acid and ethanol were 9.812, 7.76, 6.717 and 17.33 g/L respectively, displaying toxicity order of: butyric acid > propionic acid > acetic acid > ethanol being additive in nature. The toxic effects of four VFAs could be designated as synergistic and one additive in nature.