Aflatoxin binders I: in vitro binding assay for aflatoxin B1 by several potential sequestering agents

Nine potential proprietary sequestering agents consisting of 4 activated charcoals, 3 sodium bentonites, a calcium bentonite, and an esterified glucomannan were compared in a novel in vitro assay for aflatoxin B1 (AFB1) binding. Agents were evaluated in 10% methanol prepared as 1% stirred suspensions at pH 3, 7, 10 and pH-unadjusted, with or without AFB1 at 5 microg/ml. All nine agents bound more than 95% of the 5 microg of AFB1 in solution, regardless of pH. The sodium bentonites bound 98, 95, and 98% of the AFB1. The four activated charcoals bound over 99%, the calcium bentonite bound 98%, and the esterified glucomannan bound 97% of the AFB1 in solution. The results suggested that the sequestering agents tested here had sufficient potential to bind AFB1 at pH values commonly found in the gastrointestinal tracts of ruminants and other animals.     

Aflatoxin Binders II: Reduction of aflatoxin M1 in milk by sequestering agents of cows consuming aflatoxin in feed

Sequestering agents bind dietary aflatoxin B1 (AFB1) and reduce absorption from an animal's gastrointestinal tract. As a result, they protect an animal from the toxic effects of AFB1 and reduce transfer of the metabolite, aflatoxin M1 (AFM1), into milk. Three experiments, using late-lactation Holstein cows fed AFB1-contaminated feed, were conducted to evaluate several potential sequestering agents for their abilities to prevent or reduce the transmission of AFM1 into milk. Six agents previously tested in our laboratory for AFB1 binding in vitro were evaluated in these experiments. These were: SA-20, an activated carbon (AC-A); Astra-Ben-20, a sodium bentonite (AB-20); MTB-100, an esterified glucomannan (MTB-100); Red Crown, a calcium bentonite (RC); Flow Guard, a sodium bentonite (FG); and Mycrosorb, a sodium bentonite (MS). Five of the six sequestering agents significantly (P < 0.01) reduced AFM1 contamination of milk (AB-20, 61%; FG, 65%; MS, 50%; MTB-100, 59%; and RC, 31%); whereas, AC-A, activated carbon, had no effect on AFM1 transmission at 0.25% of feed. By the first milking (1 day after cows consumed contaminated feed), AFM1 appeared in milk, then reached maximum levels after three days, and was absent from milk within four days after AFB1 was removed from the feed. Sodium bentonites at 1.2% of feed showed good potential as AFB1 binders; MTB-100, a yeast cell wall product, was equally effective at 0.05% in feed. Potential AFB1 binding agents should be evaluated experimentally to demonstrate efficacy. Our data show that sequestering agents can reduce AFM1 in milk of cows fed AFB1-contaminated feed.     

Procedures for the axenic isolation of conchocelis and monospores from the red seaweed Porphyra yezoensis

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-m mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 gml^–1 GeO₂, 10 gml^–1 ampicillin, 40 gml^–1 kanamycin and 200 gml^–1 streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 g ml^–1 nystatin, 2 mgml^–1 ampicillin, 400 gml^–1 kanamycin, 50 gml^–1 neomycin and 800 gml^–1 streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel.     

Thiamin transport by human erythrocytes and ghosts

Summary Thiamin transport in human erythrocytes and resealed pink ghosts was evaluated by incubating both preparations at 37 or 20°C in the presence of [³H]-thiamin of high specific activity. The rate of uptake was consistently higher in erythrocytes than in ghosts. In both preparations, the time course of uptake was independent from the presence of Na⁺ and did not reach equilibrium after 60 min incubation. At concentrations below 0.5 m and at 37°C, thiamin was taken up predominantly by a saturable mechanism in both erythrocytes and ghosts. Apparent kinetic constants were: for erythrocytes,K _m =0.12, 0.11 and 0.10 m andJ _max=0.01, 0.02 and 0.03 pmol·l^–1 intracellular water after 3, 15, and 30 min incubation times, respectively; for ghosts,K _m =0.16 and 0.51 m andJ _max=0.01 and 0.04 pmol·l^–1 intracellular water after 15 and 30 min incubation times, respectively. At 20°C, the saturable component disappeared in both preparations. Erythrocyte thiamin transport was not influenced by the presence ofd-glucose or metabolic inhibitors. In both preparations, thiamin transport was inhibited competitively by unlabeled thiamin, pyrithiamin, amprolium and, to a lesser extent, oxythiamin, the inhibiting effect being always more marked in erythrocytes than in ghosts. Only approximately 20% of the thiamin taken up by erythrocytes was protein-(probably membrane-) bound. A similar proportion was esterified to thiamin pyrophosphate. Separate experiments using valinomycin and SCN^– showed that the transport of thiamin, which is a cation at pH 7.4, is unaffected by changes in membrane potential in both preparations.     

Susceptibility of clinical isolates of yeasts to anti-fungal agents

The antimicrobial activity of amphotericin B, 5-fluorocytosine, nystatin, clotrimazole and miconazole were compared in vitro against 244 strains of yeasts that had been isolated from clinical specimens. The yeasts used in this study included 20 species of Candida, Cryptococcus, Saccharomyces Geotrichum, Rhodotorula, Torulopsis and Trichosporon. The majority of the strains (78%) had an MIC of 0.5 g/ml for amphotericin B, 81% an MIC of 1 g/ml for 5-fluorocytosine, 99% 8 g/ml for nystatin, 91%, 8.0 g/ml for clotrimazole and 98% had an MIC of 4.0 for miconazole. Of the anti-fungal agents tested, 5-fluorocytosine and nystatin were found to have the greatest antifungal activity.     

Action of phenazine methyl sulfate,inhibitors, and uncouplers on the light-induced proton transport by cells ofRhodospirillum rubrum

Summary Suspensions of log phase cells ofRhodospirillum rubrum at pH 5.5 show a light-induced decrease in the pH of the medium which is reversed during the subsequent dark period. The velocity and magnitude of the pH change were the same whether the cells were bubbled with air, CO₂-free air or N₂ during experimentation. The pH response is temperature dependent. Phenazine methyl sulfate (PMS) at concentrations above 0.05mm stimulates the light-induced pH change. PMS at 1mm gives a 2-fold increase in the initial rate upon illumination and a 1.5-fold increase in the total change in pH after 2 min of illumination. The inhibition of the proton transport by 10 g/ml antimycin A or 20 m 2-n-heptyl-4-hydroxyquinoline-N-oxide can be partially relieved by PMS. However, inhibition of the light-induced proton transport with 0.5mm 2,4-dinitrophenol or 3 m carbonylcyanide-m-chlorophenylhydrazone (CCCP) cannot be overcome by addition of PMS. Valinomycin, at a concentration of 3 m, caused a slight stimulation of the light-induced proton transport in the presence of 200mm KCl. The inhibition of proton transport by 3 m CCCP was partially relieved with 3 m valinomycin in the presence of 200mm KCl, but the antibiotic was without effect when the cells were suspended in 200mm NaCl. The results are discussed in terms of current theories of the action of PMS, antimycin A, valinomycin, and uncouplers on the light-induced electron flow and photophosphorylation inR. rubrum.     

The effects of aluminium on nodulation and symbiotic nitrogen fixation in Casuarina cunninghamiana Miq.

In order to investigate the effects of Al on nodule formation and function in the Casuarina-Frankia symbiosis, inoculated plants were grown in sand culture at five nominal Al concentrations (0-880 M Al) at pH 4.0. There was an Al-free control at pH 6.0 to assess the effects of pH 4.0 treatments. Mean N concentration of nodules was significantly less at pH 4.0 (1.83%) than at pH 6.0 (2.01%). There were nodulated plants at all Al levels, though there were fewer nodulated plants at 440 and 880 M Al. Dry weights of nodules, shoots and roots were not reduced by Al concentrations at or below 220 M Al, but were decreased by Al concentrations at or above 440 M Al. Nodule weight expressed as a percentage of total weight did not differ significantly with respect to an Al-free control at pH 4. N concentrations of shoots and whole plants were significantly reduced at 440 M Al. Nodular specific acetylene reduction activity (ARA) did not differ significantly among Al treatments. However, N₂-fixation efficiency was decreased from 0.20 to 0.10 mg N fixed mg nodule dry weight^–1 at 880 M Al.     

The adsorption and release of tylosin by clays and soils

Summary The uptake and release of tylosin by Wyoming bentonite, Ca⁺⁺ montmorillonite, illite (Fithian Illinois) and kaolin (china clay) was studied. The adsorption capacities of bentonite and montmorillonite for tylosin were found to be 190 and 65 g mg^–1 respectively, while the adsorption capacities of illite and kaolinite were found to be 22 and 6.5 g mg^–1. 7.6 and 7.4% respectively of the tylosin adsorbed by bentonite and montmorillonite, and 30 and 25% respectively of the tylosin adsorbed by illite and kaolinite, was released in phosphate buffer.The presence of tylosin in two different soils amended with tylosin fermentation waste was also studied, and the effect of temperature on tylosin release was examined in one of the soils. The concentration of tylosin in the soil water was found to be related more to the concentration of tylosin fermentation waste than to the incubation temperature. The amounts of tylosin present in the initial leachates of the two soils, a modified John Innes compost and a limestone waste, were found to be in excess of the minimum inhibitory concentrations for susceptible bacteria. It is hypothesised that in these particular soils if the tylosin is not broken down by microbial action it could affect susceptible populations of bacteria.     

The contribution of size-fractionated plankton to biomass and primary production of phytoplankton in saline–alkaline ponds

Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l^–1 d^–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l^–1 d^–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l^–1 d^–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l^–1 d^-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l^–1 d^–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l^–1 d^–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.     

Expression of the Neurospora crassa metallothionein gene in Escherichia coli and its effect on heavy-metal uptake

The gene coding for the Neurospora crassa metallothionein protein was chemically synthesized and cloned into the fusion expression vectors pMal-c and pMal-p. Cell-fractionation experiments demonstrated the proper localization of the pMal-c- and pMal-p- expressed proteins to the cytosol and periplasm of the bacteria respectively. Control bacteria as well as the recombinant bacteria producing the metallothionein protein were incubated with solutions of ¹⁰⁹Cd at concentrations of 0.2 M, 1 M, and 10 M. The recombinant bacteria were able to accumulate significantly more ¹⁰⁹Cd than control bacteria at all concentrations tested. Cadmium accumulation was rapid and highly selective. Maximum uptake was achieved at a pH of 7.0, with lower accumulation at lower or higher pH values. The pH-dependent uptake of cadmium by the recombinant bacteria was exploited to strip off the bound cadmium from the recombinant bacteria and to regenerate most of the cadmium-binding sites. These observations suggest the potential for using a metallothionein-based biosorbent for certain heavy-metal removal applications.     

AT-1 Receptor and Phospholipase C Are Involved in Angiotensin III Modulation of Hypothalamic Noradrenergic Transmission

SUMMARY 1. We previously reported that angiotensin III modulates noradrenergic neurotransmission in the hypothalamus of the rat. In the present work we studied the effects of angiotensin III on norepinephrine release and tyrosine hydroxylase activity. We also investigated the receptors and intracellular pathways involved in angiotensin III modulation of noradrenergic transmission.2. In rat hypothalamic tissue labeled with [³H]norepinephrine 1, 10, and 100 nM and 1 M losartan (AT1 receptor antagonist) had no effect on basal neuronal norepinephrine release, whereas 10 and 100 nM and 1 M losartan partially diminished norepinephrine secretion evoked by 25 mM KCl. The AT2 receptor antagonist PD 123319 showed no effect either on basal or evoked norepinephrine release. The increase in both basal and evoked norepinephrine output induced by 1 M angiotensin III was blocked by 1 M losartan, but not by 1 M PD 123319.3. The phospholipase C inhibitor 5 M neomicin inhibited the increase in basal and evoked norepinephrine release produced by 1 M angiotensin III.4. Tyrosine hydroxylase activity was increased by 1 M angiotensin III and this effect was blocked by 1 M LST and 5 M neomicin, but not by PD 123319. On the other hand, 1 M angiotensin III enhanced phosphatidyl inositol hydrolysis that was blocked by 1 M losartan and 5 M neomicin. PD 123319 (1 M) did not affect ANG III-induced phosphatidyl inositol hydrolysis enhancement.5. Our results confirm that angiotensin III acts as a modulator of noradrenergic transmission at the hypothalamic level through the AT1-phospholipase C pathway. This enhancement of hypothalamic noradrenergic activity suggests that angiotensin III may act as a central modulator of several biological processes regulated at this level by catecholamines, such as cardiovascular, endocrine, and autonomic functions as well as water and saline homeostasis.     

Decrease of aflatoxin B1 in yoghurt and acidified milks

Fermentation of yoghurt and acidified milks containing aflatoxin B₁ (AB₁) were studied. AB₁ added to milk before fermentation at concentrations of 600, 1000 and 1400 g/kg was reduced in yoghurts (pH 4.0) by 97, 91 and 90%, respectively. Coagulation time was approximately the same as in the controls. Streptococci had longer chains than those in the controls. The main decrease of AB₁ occurred during the milk fermentation. A decrease of AB₁ (conc. 1000 g/kg) in milks acidified with citric, lactic and acetic acids (pH 4.0) was 90, 84 and 73%, respectively.     

Morphometric and autoradiographic analysis of crude synaptosomal preparations from rat cerebral cortex

Morphometric and autoradiographic studies have been made of a crude synaptosomal preparation, which has been used extensively for membrane transport studies. When filters are used to separate membrane bound structures from incubation medium, the structures which survive filtration are those that are entrapped within the matrix of the filter structure. The population of membrane bound structures differs when one compares pellets of the preparation to sections of loaded 0.45 and 0.65 m pore size filters. Both the relative numbers of synaptosomes, mitochondria, and other membrane bound structures (OMBS) and the mean size of each of the structures differ for pellet, 0.45 m, and 0.65 m filters. The percentage of total membrane bound volume attributable to synaptosomes increases from 28 in the crude preparation to 40 in 0.45 m filters and 61 in 0.65 m filters. The total volume of synaptosomes entrapped by differing pore size filters roughly correlates with the amount of substrate uptake. Neither mitochondrial volume nor the volume of other membrane bound structures was found to correlate with uptake. These results indicated that only the synaptosomes contribute measurably to this function. Autoradiographic studies confirm this conclusion. EM autoradiography following loading of the synaptosomal preparation with tritiated glutamate or GABA showed about 81% of the grains to be associated with synaptosomes. It is concluded that crude synaptosomal preparations may be used without further purification for membrane transport studies with unambiguous results.     

Properties of acetylcholinesterase reconstituted in liposomes of a different charge

Acetylcholinesterase (AChE) purified from mouse brain was reconstituted in liposomes of a different charge, and the properties of liposome-associated AChE were investigated. Relative to the K_m value (38.5 M) of AChE bound to a neutral liposome, the value of AChE reconstituted in a negatively-charged liposome decreased to 23.3 M, whereas that of AChE in a positively-charged liposome increased to 90.9 M. Additionally, AChE bound to a positively-charged liposome expressed a wider range of optimum pH than the enzyme in a negatively-charged liposome. In a stability study, it was found that soluble AChE was unstable at pH 5.5 and 7.4, while it was relatively stable at pH 10. Noteworthy, the immobilization of AChE to liposome enhanced the stability of soluble enzyme at acidic and neutral pH. Moreover, in the stabilization of the enzyme, a neutral liposome was more effective than charged liposomes, of which a positively-charged liposome was more effective than a negatively-charged liposome at acidic pH. Based on these results, it is proposed that while the K_m value and the pH dependence of AChE activity are affected by the charge of liposome, the stability of AChE is determined mainly by a hydrophobic binding to a phospholipid membrane.This work was supported in part by Agency for Defense Development.     

Semicontinuous anaerobic digestion of soft drink wastewater in immobilised cell bioreactors

Summary Saponite support considerably increased the kinetics of a. semicontinuous anaerobic digestion process treating soft drink wastewater showing values of the _max andK kinetic parameters (Chen and Hashimoto model) 2.5 and 1.4 times higher than for bentonite and polyurethane support, respectively. This was significant at 95% confidence level.     

Effects of aluminium and low pH on growth and development in Rana temporaria tadpoles

Summary Rana temporaria tadpoles were raised to metamorphosis at 6 levels of pH (pH 3.6–6.5) and 2 levels of aluminium (800 and 1,600 g l^-1) at pH 4.4. Treatments involved both chronic and acute exposure to depressed pH. Decreasing pH reduced maximum body size and delayed metamorphosis. Growth was depressed and metamorphosis delayed by 800 g l^-1 Al, and several tadpoles died at foreleg emergence. At 1,600 g l^-1 Al, small tadpoles suffered arrested growth and development and eventually died, while larger tadpoles metamorphosed without delay, though at a very small size. There was no mortality among controls. The levels of pH and inorganic monomeric aluminium measured in the experiments were similar to field levels at a site in Scotland, and it is concluded that individual tadpoles will, in certain types of water body, be adversely affected by both acidity and aluminium. The impact of these factors on populations remains to be determined.     

Isolation and culture of Lens culinaris Medik. cv. Eston epicotyl protoplasts to calli

Protoplasts of Lens culinaris Medik. cv. Eston were isolated from epicotyl tissues of seedlings grown on Murashige & Skoog basal medium. For isolating the protoplasts, epicotyl tissues were digested for 12–14 h at 25°C in an isolation mixture (pH 5.7) containing 1% Cellulase RS, 0.5% Driselase, 0.25% Pectolyase Y23, 0.2M calcium chloride, 10 mM mannitol and 10 mM MES. Protoplasts were purified by flotation over 20% sucrose and washed with 0.2 M calcium chloride solution supplemented with 10 mM mannitol. Purified protoplasts were cultured at a density of 10⁵ ml^-1 in agarose (Seaplaque, 0.6%) blocks which were suspended in an identical but liquid KM8P culture medium lacking amino acids, ammonium nitrate, and coconut water but containing 0.35 M glucose and a growth regulator complement of either 2.2 M 2,4-dichlorophenoxyacetic acid (2,4-D), 2.7 M naphthaleneacetic acid (NAA), 2.3 M N-(2-furanylmethyl)-1H-purine-6-amine (kinetin), 2.2 M benzylamino purine (BAP), 2.3 M 2-methyl-4-(1H-purine-6-ylamino)-2-buten-1-ol (zeatin), and 1.4 M gibberellic acid (GA₃), or 5.4 M NAA and 2.2 M each of 2,4-D and BAP. The osmotic potential of the liquid culture medium was gradually reduced over a period of 3 weeks by replacing the spent medium with a fresh medium containing 0.25, 0.1 and 0 M glucose at weekly intervals. About 6% of the dividing protoplasts developed into cell colonies after 3 weeks of culture at 25°C in diffuse light (10 E m^-2s^-1). In 35–42 days the microcolonies were about 1 mm in diameter and developed into calli on transfer to agar-solidified B5 medium supplemented with growth regulators used in the protoplast culture medium and 5 mM glutamine. Attempts to regenerate plants from protoplast-derived calli have so far been unsuccessful.Department of Applied Microbiology and Food Science, University of Saskatchewan     

Release of the periplasmic penicillinases from Escherichia coli by toluene

Summary More than 80% of the chromosomally and R factor mediated, periplasmic penicillinases of Escherichia coli K-12, strains G11a1 and D1-R1, are released into the medium upon treatment with the membrane damaging agents toluene (50 l/ml) or polymyxin B (10 g/ml) within 10 min of incubation at 37°C. A concomitant release of protein (27 to 34%), but not of the cytoplasmic -galactosidase (<5%) occurs.     

HCO 3 - and OH-transport across the plasmalemma ofChara

Internodal and whorl (branch) cells of the green alga,Chara corallina Klein ex Willd., em. R.D.W., were studied with the extracellular vibrating probe for measuring transmembrane ion currents, and with an extracellular pH microprobe for measuring the surface pH profile. Bands of positive inward current (OH^- efflux) 1–3 mm wide were separated by wider bands of outward current (HCO ₃ ^- influx) along the length of the cell. The measured peaks of inward current ranged from 20 to 60 A cm^-2 (98 m from the cell surface) which would correspond to a surface ionic flux of 270–800 pmol cm^-2 s^-1. The peaks of outward current (HCO ₃ ^- influx) ranged from 10 to 30 A cm^-2 which would correspond to a surface ionic flux of 140–400 pmol cm^-2 s^-1. The inward current bands matched the regions of surface alkalinity very well. The outward current (HCO ₃ ^- influx) was reduced at least 10-fold in low-HCO ₃ ^- medium, with a commensurate readjustment in the strength and pattern of inward current (OH^- efflux). (Although these experiments involved a manipulation of the external pH, it is felt that the main adjustment in current patterns was in response to the reduction in exogenous HCO ₃ ^- ). The presence of the vibrating probe perturbed the inward current region when vibrating with a 26-m amplitude, but this perturbation was eliminated when a 7-m amplitude was used. The perturbation was usually observed as a reduction in the number of inward current peaks with an increase (approximate doubling) in the amplitudes of the one or two remaining peaks. Both the inward and outward currents were light-dependent, falling off within seconds of light removal.     

Growth and lactic acid production ofPediococcus pentosaceus at different gas environments,temperatures, pH values and nitrite concentrations

Summary In order to obtain a better understanding of the behaviour ofPediococcus pentosaceus in food products as well to facilitate the designing of industrial production processes for the organism, the growth and lactic acid production ofPediococcus pentosaceus in a complex glucose medium was followed in batch cultures at different gas environments (CO₂, air, N₂ and static cultures without gasflow), temperatures (10–50°C), pH (4.3–7.3) and nitrite concentrations (0–700 ppm). Optimal growth was obtained in CO₂ at 40°C and pH 6.3 and resulted in a maximum specific growth rate ( _max) of 1.27 h^–1. In static culture at 40°C and pH 6.3 the _max was 1.21 h^–1. The _max was, compared with static culture, reduced in air (12%) and nitrogen (26%). At 10°C the _max was reduced by 99% and at 50°C by 88%. The reduction at pH 4.3 and 7.3 was 65% and 57%, respectively. Nitrite did not affect the _max at any pH but increased the lag phase at pH 4.3 by a factor of 12. The lactic acid production was linked to the growth. The total amount of lactic acid produced was the same in all the tested gases and nitrite concentrations and also within the wide temperature range (15–45°C) and pH range (5.3–7.3). Mainly L(+)-lactic acid was produced during the exponential growth phase, but after this growth declined about 30% of the L(+)-lactic acid was converted to D(–)-lactic acid. The lactic acid product yield and the cellmass yied were both affected by the temperature but not by the pH.