Enzymatic synthesis of monoglycerides by esterification reaction using Penicillium camembertii lipase immobilized on epoxy SiO2-PVA composite

Glycerol-fatty acid esterification has been conducted with lipase from Penicillium camembertii lipase immobilized on epoxy SiO₂-PVA in solvent-free media, with the major product being 1-monoglyceride, a useful food emulsifier. For a given set of initial conditions, the influence of reaction was measured in terms of product formation and selectivity using different fatty acids as acyl donors. Results were found to be relatively dependent of the chain length of the fatty acids, showing high specificity for both myristic and palmytic acids attaining final mixture that fulfills the requirements established by the World Health Organization to be used as food emulsifiers.     

Isolation and characterization of lactic acid bacteria from yan-taozih (pickled peaches) in Taiwan

Two hundred cultures of lactic acid bacteria were isolated from eight yan-taozih (pickled peaches) samples, and four cultures were isolated from the main component of these samples, fresh peaches. Phenotypic and biochemical characteristics identified eight different bacterial groups (A–H) and showed that the majority of the isolates was heterofermentative lactic acid bacteria. The most common bacterial species in yan-taozih was Leuconostoc mesenteroides, although regional diversity was also observed among the lactic acid bacteria strains isolated. The antibacterial activities of the isolates were also determined, and 20 isolates were found to show inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157^T. The results of the sensory evaluation suggested that the diversity of lactic acid bacteria has a great effect on the aroma and formation of taste in the food product. Our findings suggest that Leuconostoc mesenteroides is the most abundant lactic acid bacteria in yan-taozih (pickled peaches) and that lactic acid bacteria strains play an important role in affecting the aroma and taste of the food product.     

Four-carbon dicarboxylic acid production through the reductive branch of the open cyanobacterial tricarboxylic acid cycle in Synechocystis sp. PCC 6803

Succinate, fumarate, and malate are valuable four-carbon (C4) dicarboxylic acids used for producing plastics and food additives. C4 dicarboxylic acid is biologically produced by heterotrophic organisms. However, current biological production requires organic carbon sources that compete with food uses. Herein, we report C4 dicarboxylic acid production from CO₂ using metabolically engineered Synechocystis sp. PCC 6803. Overexpression of citH, encoding malate dehydrogenase (MDH), resulted in the enhanced production of succinate, fumarate, and malate. citH overexpression increased the reductive branch of the open cyanobacterial tricarboxylic acid (TCA) cycle flux. Furthermore, product stripping by medium exchanges increased the C4 dicarboxylic acid levels; product inhibition and acidification of the media were the limiting factors for succinate production. Our results demonstrate that MDH is a key regulator that activates the reductive branch of the open cyanobacterial TCA cycle. The study findings suggest that cyanobacteria can act as a biocatalyst for converting CO₂ to carboxylic acids.     

Identification of Lactic Acid Bacteria from Chili Bo, a Malaysian Food Ingredient

Ninety-two strains of lactic acid bacteria (LAB) were isolated from a Malaysian food ingredient, chili bo, stored for up to 25 days at 28°C with no benzoic acid (product A) or with 7,000 mg of benzoic acid kg⁻¹ (product B). The strains were divided into eight groups by traditional phenotypic tests. A total of 43 strains were selected for comparison of their sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) whole-cell protein patterns with a SDS-PAGE database of LAB. Isolates from product A were identified as Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus farciminis, Pediococcus acidilactici, Enterococcus faecalis, and Weissella confusa. Five strains belonging to clusters which could not be allocated to existing species by SDS-PAGE were further identified by 16S rRNA sequence comparison. One strain was distantly related to the Lactobacillus casei/Pediococcus group. Two strains were related to Weissella at the genus or species level. Two other strains did not belong to any previously described 16S rRNA group of LAB and occupied an intermediate position between the L. casei/Pediococcus group and the Weissella group and species of Carnobacterium. The latter two strains belong to the cluster of LAB that predominated in product B. The incidence of new species and subspecies of LAB in chili bo indicate the high probability of isolation of new LAB from certain Southeast Asian foods. None of the isolates exhibited bacteriocin activity against L. plantarum ATCC 14917 and LMG 17682.     

Identification and Characterization of a Novel Staphylococcal Emetic Toxin

Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus have superantigenic and emetic activities, which cause toxic shock syndrome and staphylococcal food poisoning, respectively. Our previous study demonstrated that the sequence of SET has a low level of similarity to the sequences of other SEs and exhibits atypical bioactivities. Hence, we further explored whether there is an additional SET-related gene in S. aureus strains. One SET-like gene was found in the genome of S. aureus isolates that originated from a case of food poisoning, a human nasal swab, and a case of bovine mastitis. The deduced amino acid sequence of the SET-like gene showed 32% identity with the amino acid sequence of SET. The SET-like gene product was designated SElY. In the food poisoning and nasal swab isolates, mRNA encoding SElY was highly expressed in the early log phase of cultivation, whereas a high level of expression of this mRNA was found in the bovine mastitis isolate at the early stationary phase. To estimate whether SElY has both superantigenic and emetic activities, recombinant SElY was prepared. Cell proliferation and cytokine production were examined to assess the superantigenic activity of SElY. SElY exhibited superantigenic activity in human peripheral blood mononuclear cells but not in mouse splenocytes. In addition, SElY exhibited emetic activity in house musk shrews after intraperitoneal and oral administration. However, the stability of SElY against heating and pepsin and trypsin digestion was different from that of SET and SEA. From these results, we identified SElY to be a novel staphylococcal emetic toxin.     

Histamine-Producing Pathway Encoded on an Unstable Plasmid in Lactobacillus hilgardii 0006

Histamine production from histidine in fermented food products by lactic acid bacteria results in food spoilage and is harmful to consumers. We have isolated a histamine-producing lactic acid bacterium, Lactobacillus hilgardii strain IOEB 0006, which could retain or lose the ability to produce histamine depending on culture conditions. The hdcA gene, coding for the histidine decarboxylase of L. hilgardii IOEB 0006, was located on an 80-kb plasmid that proved to be unstable. Sequencing of the hdcA locus disclosed a four-gene cluster encoding the histidine decarboxylase, a protein of unknown function, a histidyl-tRNA synthetase, and a protein, which we named HdcP, showing similarities to integral membrane transporters driving substrate/product exchange. The gene coding for HdcP was cloned downstream of a sequence specifying a histidine tag and expressed in Lactococcus lactis. The recombinant HdcP could drive the uptake of histidine into the cell and the exchange of histidine and histamine. The combination of HdcP and the histidine decarboxylase forms a typical bacterial decarboxylation pathway that may generate metabolic energy or be involved in the acid stress response. Analyses of sequences present in databases suggest that the other two proteins have dispensable functions. These results describe for the first time the genes encoding a histamine-producing pathway and provide clues to the parsimonious distribution and the instability of histamine-producing lactic acid bacteria.     

A study of tolerance of ingested tannin in Schistocerca gregaria

A study has been made on the effects of ingestion of tannic acid on growth and development of Schistocerca gregaria. No deleterious effects were found on digestion or utilisation of food, even when food protein levels were very low. At high concentrations consumption rates were relatively low over the first day, but this effect was not sustained. The lack of ‘antidigestive’ effects is shown to be due partly to the hydrolysis of tannic acid to gallic acid and glucose, and partly to the adsorptive properties of the peritrophic membrane. Insects reared on food with high levels of tannic acid took a longer time to reach sexual maturity than did the controls, although fecundity was not affected thereafter.     

A Likelihood-Based Approach to Identifying Contaminated Food Products Using Sales Data: Performance and Challenges

Foodborne disease outbreaks of recent years demonstrate that due to increasingly interconnected supply chains these type of crisis situations have the potential to affect thousands of people, leading to significant healthcare costs, loss of revenue for food companies, and—in the worst cases—death. When a disease outbreak is detected, identifying the contaminated food quickly is vital to minimize suffering and limit economic losses. Here we present a likelihood-based approach that has the potential to accelerate the time needed to identify possibly contaminated food products, which is based on exploitation of food products sales data and the distribution of foodborne illness case reports. Using a real world food sales data set and artificially generated outbreak scenarios, we show that this method performs very well for contamination scenarios originating from a single “guilty” food product. As it is neither always possible nor necessary to identify the single offending product, the method has been extended such that it can be used as a binary classifier. With this extension it is possible to generate a set of potentially “guilty” products that contains the real outbreak source with very high accuracy. Furthermore we explore the patterns of food distributions that lead to “hard-to-identify” foods, the possibility of identifying these food groups a priori, and the extent to which the likelihood-based method can be used to quantify uncertainty. We find that high spatial correlation of sales data between products may be a useful indicator for “hard-to-identify” products.     

Climate Effects on High Latitude Daphnia via Food Quality and Thresholds

Climate change is proceeding rapidly at high northern latitudes and may have a variety of direct and indirect effects on aquatic food webs. One predicted effect is the potential shift in phytoplankton community structure towards increased cyanobacterial abundance. Given that cyanobacteria are known to be a nutritionally poor food source, we hypothesized that such a shift would reduce the efficiency of feeding and growth of northern zooplankton. To test this hypothesis, we first isolated a clone of Daphnia pulex from a permafrost thaw pond in subarctic Québec, and confirmed that it was triploid but otherwise genetically similar to a diploid, reference clone of the same species isolated from a freshwater pond in southern Québec. We used a controlled flow-through system to investigate the direct effect of temperature and indirect effect of subarctic picocyanobacteria (Synechococcus) on threshold food concentrations and growth rate of the high latitude clone. We also compared the direct effect of temperature on both Daphnia clones feeding on eukaryotic picoplankton (Nannochloropsis). The high latitude clone had a significantly lower food threshold for growth than the temperate clone at both 18 and 26°C, implying adaptation to lower food availability even under warmer conditions. Polyunsaturated fatty acids were present in the picoeukaryote but not the cyanobacterium, confirming the large difference in food quality. The food threshold for growth of the high latitude Daphnia was 3.7 (18°C) to 4.2 (26°C) times higher when fed Synechococcus versus Nannochloropsis, and there was also a significant negative effect of increased temperature and cyanobacterial food on zooplankton fatty acid content and composition. The combined effect of temperature and food quality on the performance of the high latitude Daphnia was greater than their effects added separately, further indicating the potentially strong indirect effects of climate warming on aquatic food web processes.     

Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end‐product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA‐producing Aureobasidium pullulans strain ZX‐10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high‐titer equivalent to 87.6 g/L of malic acid and high‐productivity of 0.61 g/L h in free‐cell fermentation in a stirred‐tank bioreactor. Fed‐batch fermentations with cells immobilized in a fibrous‐bed bioreactor (FBB) achieved the highest product titer of 144.2 g/L and productivity of 0.74 g/L h. The fermentation produced PMA was purified by adsorption with IRA‐900 anion‐exchange resins, achieving a ～100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2 M sulfuric acid at 85°C, which followed the first‐order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. Biotechnol. Bioeng. 2013; 110: 2105–2113. © 2013 Wiley Periodicals, Inc.     

THE INFLUENCE OF THE MODE OF NUTRITION ON THE DIGESTIVE SYSTEM OF OCHROMONAS MALHAMENSIS

The intracellular distribution and level of acid hydrolases in Ochromonas malhamensis were studied in cells grown osmotrophically in a defined medium, in a carbon-free starvation medium, and during phagotrophy in each of these media. By cytochemical techniques, little enzymic reaction product was observed in the vacuoles of osmotrophic cells grown in the defined medium. Starved cells, however, contained autophagic vacuoles and cannibalized other Ochromonas cells. Dense enzymic reaction product was observed in the digestive vacuoles and in the Golgi cisternae of these starved cells. Moreover, starved cells and cells grown in a nutritionally complete medium ingested Escherichia coli which appeared in digestive vacuoles containing enzymic reaction product. Biochemical assays for lysosomal acid phosphatase (E.C. 3.1.3.2 orthophosphoric monoester phosphohydrolase) and acid ribonuclease (E.C. 2.7.7.16 ribonucleate nucleotido-2'-transferase) were done on Ochromonas cultures in the same experimental treatments and under identical assay conditions as the cytochemical study. During starvation, the acid hydrolase specific activities were consistently twice those found in cells grown in an osmotrophic complete medium. Ochromonas fed E. coli showed no increase in acid hydrolase specific activity as compared to controls not fed E. coli. The latency of lysosomal acid hydrolases in cells fixed with glutaraldehyde was reduced, suggesting that this fixative increases lysosomal membrane permeability and may release enzymes or their reaction products into the cytoplasmic matrix during cytochemical analysis. This could explain the cytoplasmic staining artifact sometimes observed with glutaraldehyde-fixed cells when studied by the Gomori technique. This study confirms that Ochromonas malhamensis, a phytoflagellate, does produce digestive vacuoles and can ingest bacteria, thereby fulfilling its role as a heterotroph in an aquatic food chain. When Ochromonas is grown in a nutritionally complete osmotrophic medium, phagocytosis causes appearance of acid hydrolases in the digestive vacuoles, whereas the total activity of the enzymes remains unchanged. An organic carbon-free medium strongly stimulates acid hydrolaes activity and causes these enzymes to appear in the digestive vacuoles whether phagocytosis occurs or not.     

Efficient Whole-Cell Biocatalyst for Acetoin Production with NAD+ Regeneration System through Homologous Co-Expression of 2,3-Butanediol Dehydrogenase and NADH Oxidase in Engineered Bacillus subtilis

Acetoin (3-hydroxy-2-butanone), an extensively-used food spice and bio-based platform chemical, is usually produced by chemical synthesis methods. With increasingly requirement of food security and environmental protection, bio-fermentation of acetoin by microorganisms has a great promising market. However, through metabolic engineering strategies, the mixed acid-butanediol fermentation metabolizes a certain portion of substrate to the by-products of organic acids such as lactic acid and acetic acid, which causes energy cost and increases the difficulty of product purification in downstream processes. In this work, due to the high efficiency of enzymatic reaction and excellent selectivity, a strategy for efficiently converting 2,3-butandiol to acetoin using whole-cell biocatalyst by engineered Bacillus subtilis is proposed. In this process, NAD⁺ plays a significant role on 2,3-butanediol and acetoin distribution, so the NADH oxidase and 2,3-butanediol dehydrogenase both from B. subtilis are co-expressed in B. subtilis 168 to construct an NAD⁺ regeneration system, which forces dramatic decrease of the intracellular NADH concentration (1.6 fold) and NADH/NAD⁺ ratio (2.2 fold). By optimization of the enzymatic reaction and applying repeated batch conversion, the whole-cell biocatalyst efficiently produced 91.8 g/L acetoin with a productivity of 2.30 g/(L·h), which was the highest record ever reported by biocatalysis. This work indicated that manipulation of the intracellular cofactor levels was more effective than the strategy of enhancing enzyme activity, and the bioprocess for NAD⁺ regeneration may also be a useful way for improving the productivity of NAD⁺-dependent chemistry-based products.     

Benzoic Acid, a Weak Organic Acid Food Preservative, Exerts Specific Effects on Intracellular Membrane Trafficking Pathways in Saccharomyces cerevisiae

Microbial spoilage of food causes losses of up to 40% of all food grown for human consumption worldwide. Yeast growth is a major factor in the spoilage of foods and beverages that are characterized by a high sugar content, low pH, and low water activity, and it is a significant economic problem. While growth of spoilage yeasts such as Zygosaccharomyces bailii and Saccharomyces cerevisiae can usually be retarded by weak organic acid preservatives, the inhibition often requires levels of preservative that are near or greater than the legal limits. We identified a novel synergistic effect of the chemical preservative benzoic acid and nitrogen starvation: while exposure of S. cerevisiae to either benzoic acid or nitrogen starvation is cytostatic under our conditions, the combination of the two treatments is cytocidal and can therefore be used beneficially in food preservation. In yeast, as in all eukaryotic organisms, survival under nitrogen starvation conditions requires a cellular response called macroautophagy. During macroautophagy, cytosolic material is sequestered by intracellular membranes. This material is then targeted for lysosomal degradation and recycled into molecular building blocks, such as amino acids and nucleotides. Macroautophagy is thought to allow cellular physiology to continue in the absence of external resources. Our analyses of the effects of benzoic acid on intracellular membrane trafficking revealed that there was specific inhibition of macroautophagy. The data suggest that the synergism between nitrogen starvation and benzoic acid is the result of inhibition of macroautophagy by benzoic acid and that a mechanistic understanding of this inhibition should be beneficial in the development of novel food preservation technologies.     

Gene Sequence and Properties of an s-Triazine Ring-Cleavage Enzyme from Pseudomonas sp. Strain NRRLB-12227

Pesticides based on the s-triazine ring structure are widely used in cultivation of food crops. Cleavage of the s-triazine ring is an important step in the mineralization of s-triazine compounds and hence in their complete removal from the environment. Cyanuric acid amidohydrolase cleaves cyanuric acid (2,4,6-trihydroxy-s-triazine), which yields carbon dioxide and biuret; the biuret is subject to further metabolism, which yields CO₂ and ammonia. The trzD gene encoding cyanuric acid amidohydrolase was cloned into pMMB277 from Pseudomonas sp. strain NRRLB-12227, a strain that is capable of utilizing s-triazines as nitrogen sources. Hydrolysis of cyanuric acid was detected in crude extracts of Escherichia coli containing the cloned gene by monitoring the disappearance of cyanuric acid and the appearance of biuret by high-performance liquid chromatography (HPLC). DEAE and hydrophobic interaction HPLC were used to purify cyanuric acid amidohydrolase to homogeneity, and a spectrophotometric assay for the purified enzyme was developed. The purified enzyme had an apparent K_m of 0.05 mM for cyanuric acid at pH 8.0. The enzyme did not cleave any other s-triazine or hydroxypyrimidine compound, although barbituric acid (2,4,6-trihydroxypyrimidine) was found to be a strong competitive inhibitor. Neither the nucleotide sequence of trzD nor the amino acid sequence of the gene product exhibited a significant level of similarity to any known gene or protein.     

Applicability of pectate-entrapped <Emphasis Type="Italic">Lactobacillus casei</Emphasis> cells for <Emphasis Type="SmallCaps">l</Emphasis>(+) lactic acid production from whey

Lactic acid is a versatile organic acid, which finds major application in the food, pharmaceuticals, and chemical industries. Microbial fermentation has the advantage that by choosing a strain of lactic acid bacteria producing only one of the isomers, an optically pure product can be obtained. The production of l(+) lactic acid is of significant importance from nutritional viewpoint and finds greater use in food industry. In view of economic significance of immobilization technology over the free-cell system, immobilized preparation of Lactobacillus casei was employed in the present investigation to produce l(+) lactic acid from whey medium. The process conditions for the immobilization of this bacterium using calcium pectate gel were optimized, and the developed cell system was found stable during whey fermentation to lactic acid. A high lactose conversion (94.37%) to lactic acid (32.95 g/l) was achieved with the developed immobilized system. The long-term viability of the pectate-entrapped bacterial cells was tested by reusing the immobilized bacterial biomass, and the entrapped bacterial cells showed no decrease in lactose conversion to lactic acid up to 16 batches, which proved its high stability and potential for commercial application.     

Modelling and simulation of cell growth dynamics, substrate consumption, and lactic acid production kinetics of Lactococcus lactis

Lactococcus lactis species have been and still are extensively investigated due to their significant commercial importance. Current scientific research focuses on strains utilized in food industry, due to their multiple uses in food and beverages fabrication. Biomass of Lactococcus lactis is of great interest as well as the end products of its metabolism such as lactic acid and nisin. However their production is constantly challenged due to end product inhibition occurring during intensive propagation of the coccus in reactor systems. To successfully predict the behavior of the culture, the approach of combining mathematics with biology, ergo the development of an unstructured mathematical model, was taken. Although Luedeking and Piret is the model that has been extensively used to demonstrate growth in end-product inhibition cultures, its applicability is limited due to its dependance on the specific growth and product coefficients, particularly related to the culturing conditions used. To overcome these hurdles, a combination of the non competitive single product end inhibition Taylor and Hinselwood models was used, with the significance of this model laying in the fact that it offers a feasible alternative to the commonly used model of Luedeking and Piret for describing fermentation kinetics governed by end-product inhibitions. The fitting with the experimental values, in batch mode, was tested in terms of the coefficient of determination (R²), having values 0.97 ～ 0.99 and suggesting a very good fitting with the experimental data. The model was further developed to achieve theoretical predictions of volumetric cell productivity in continuous and fed-batch mode of substrate feed in different culturring systems.     

Mapping of major and modifying genes for high oleic acid content in safflower

Oils with high oleic acid content are in great demand because they have optimal properties for food and non-food uses. Two different levels of high oleic acid content (>75 and >84%) have been reported in safflower (Carthamus tinctorius L.). The trait is mainly controlled by partially recessive alleles at a major gene Ol, but the highest levels have been attributed to modifying genes. The objectives of this research were to map the Ol locus and modifying genes involved in oleic acid content of safflower seeds and to determine the nature of Ol through a candidate gene approach. Two F2 mapping populations from the nuclear male-sterile line CL-1 and the high oleic acid lines CR-6 (>75% oleic acid) and CR-9 (>84%) were developed and phenotyped for oleic acid content at the F2 and F3 seed level. A genetic linkage map comprising 15 linkage groups and 116 random amplified polymorphic DNA, simple sequence repeat (SSR), and sequence-characterized amplified regions marker loci was constructed for the CL-1?×?CR-9 population. The Ol gene was mapped to linkage group (LG) T3 tightly linked to the SSR marker ct365, which was confirmed in the CL-1?×?CR-6 population. Additionally, a quantitative trait locus with a minor effect on increasing oleic acid content was identified on LG T2. The candidate gene approach indicated that an oleoyl-phosphatidylcholine desaturase FAD2-1 locus underlies the Ol gene. Both the genetic information and the markers developed in this research will contribute to marker-assisted selection for high oleic acid content in safflower.     

Effect of food level on the growth and survival of laboratory-reared larvae of bay anchovy (anchoa mitchilli Valenciennes) and scaled sardine (harengula pensacolae Goode & Bean)

The effect of food levels on the growth and survival of laboratory-reared larvae of scaled sardines (Harengula pensacolae Goode & Bean) and bay anchovies (Anchoa mitchilli Valenciennes) was determined. Wild zooplankton, most of which was copepod nauplii and copepodids, was used as food. H. pensacolae larvae grew 0.80 mm/day at a low (444 organisms/1) and high food level (1324 organisms/1). Survival was appreciably better (14.5%) at the low than (3.5%) at the high food level, 23 days after hatching. A. mitcchilli larvae grew faster at medium and high food concentrations. Average growth rates for three replicated experiments were 0.48 mm/day at low food (621–692 organisms/1), 0.50 mm/day a t medium food (1330–1688 organisms/1), and 0.54 mm/day at high food (2811–3323 organisms/1). Survival of A. mitchilli larvae, 20 to 28 days after hatching, ranged from 0.0 to 17.8% and was better at medium and high food levels than at the low food level. The resultsng indicate that 500 to 1000 copepod nauplii and copepodids/1 provided adequate food for rearing H. pensacolae but 1500–2000/1 were consistently required to rear A. mitchilli.     

Nucleic acid indices of egg production in the tropical copepod Acartia sinjiensis

Two experiments were conducted to evaluate the effects of food and temperature on the nucleic acid content and egg production (and their relationship) of the tropical copepod Acartia sinjiensis. Experiment 1 evaluated the effect of food quality (as different algae species) on the relationship between nucleic acid content and egg production. In Experiment 2, the main and interaction effects of food type, food concentration and temperature on the total, Carbon and Nitrogen specific egg production and nucleic acid indices were evaluated in a factorial experimental design. Food quality, concentration and temperature significantly affected the nucleic acid content, egg production rate and the nucleic acid-egg production relationship of A. sinjiensis. RNA indices were correlated with egg production in females fed Pavlova salina, Tetraselmis chuii and Chaetoceros muelleri, but not in females fed Isochrysis aff. galbana. The slopes of the linear regressions of RNA indices as predictors of egg production were similar in females fed different algae species, suggesting that the slope of these relationships might be independent of food quality. The DNA content of females was significantly affected by food and temperature, suggesting that it is not a good index of cell number in this species. Nevertheless, the RNA:DNA ratio was as good a predictor of egg production as total RNA content. Egg production showed a weakly positive correlation with temperature. On the other hand, total, C- and N-specific nucleic acid indices had a strong negative correlation with temperature. In addition, temperature had a non linear effect on the slopes of the regression lines of RNA content and RNA:DNA ratio as predictors of egg production—slopes were similar at 25 °C and 30 °C, but significantly lower at 20 °C. Furthermore, the predictability of egg production was improved when the interaction term of nucleic acid indices with temperature was used instead of the nucleic acid indices alone in linear regression models. Our results suggest food quality has a limited influence on the nucleic acid-egg production relationship, and that temperature should be accounted for in models using nucleic acid indices as predictors of egg production in A. sinjiensis.     

Dekkera bruxellensis and Lactobacillus vini Form a Stable Ethanol-Producing Consortium in a Commercial Alcohol Production Process

The ethanol production process of a Swedish alcohol production plant was dominated by Dekkera bruxellensis and Lactobacillus vini, with a high number of lactic acid bacteria. The product quality, process productivity, and stability were high; thus, D. bruxellensis and L. vini can be regarded as commercial ethanol production organisms.