Pre- and postnatal energetics of the North Island brown kiwi (Apteryx mantelli)

In four eggs and four chicks of the North Island brown kiwi (Apteryx mantelli) we measured pre- and postnatal oxygen consumption rate (VO(2)) daily from day (d)-75 (prior to hatching) until d+25 (after hatching). The increase of embryonic VO(2) reaches a plateau phase between d-22 and d-5 (0.113 ml O(2)/g/h=59.6% of allometrically expected value of a typical 416-g egg). Mean total O(2) uptake per egg (43.01 l O(2)) corresponds to an energy turnover rate of 2.04 kJ/g during embryonic development. This is nearly identical to the expected value for all birds (2.00+/-0.8 kJ/g). Hence, the kiwi neither 'gained nor lost energy' (Calder, 1979.Biosci. 8, 461-467) by its extreme prolongation of incubation time; it is as efficient as other avian embryos. The kiwi embryo expends only approximately 17% (847 kJ) of the energy originally stored in the egg (4942 kJ). Forty-eight percent of the egg's initial yolk mass can be found as spare yolk in the hatchling and can serve as the chick's sole source of energy and substrate for tissue production for up to at least 17 days after hatching.     

Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing

Laying hens are increasingly kept in barn or free-range systems, which not only allows birds to move freely but also potentially entails higher energy expenditures due to higher locomotor activity. Therefore, the aim of our study was to quantify the daily energy expenditure (DEE) and water turnover in freely moving laying hens. For that purpose, 10 Lohmann Selected Leghorn (LSL) and 10 Lohmann Brown (LB) hens were obtained from a conventional breeding company at 17 weeks of age. The trial started when birds reached an age of 34 weeks. All 20 birds were kept together in the same littered floor pen (12.1 m²). The pen was equipped with perches, a nest box, feeding and nipple drinkers. The DEE was determined individually for all experimental birds (n = 20) for a total of nine days using the doubly labelled water (DLW) method. Lohmann Brown hens were heavier than LSL hens, but laying rate did not differ between the two breeds, that is, one egg per hen and day during the study period. Average egg mass was 63.1 ± 0.20 g in LB and 61.7 ± 0.12 g in LSL hens, which converted to an egg energy content of 420 and 410 kJ/egg, respectively. Dilution spaces for oxygen and hydrogen differed between the breeds but not the respective turnover rates. Total body water as a percentage of body mass (LB: 54.4%, LSL: 53.8%; SEM = 0.7, F_1,18 = 0.41, P = 0.513) and total water intake (TWI) per day (LB: 275 ml/day, LSL: 276 ml/day; SEM = 20, F_1,17 = 0, P = 0.994) did not differ between LB and LSL hens. Individual DEE increased with body mass in LB but not in LSL hens. Average DEE did not differ between the two breeds (LB: 1 501 kJ/day; LSL: 1 520 kJ/day; SEM = 32.1, F_1,17 = 2.54, P = 0.131). However, when comparing the DEE on a metabolic mass basis, LSL hens expended with 984 kJ/kg^0.75 on average significantly more energy per day than LB hens (895 kJ/kg^0.75; SEM = 20.3, F_1,18 = 10.1, P = 0.005). Our results suggest that the DLW technique is a viable method to measure the energy expenditure and water turnover over several days in laying hens. Furthermore, we show that laying hens kept in floor pens fit into the general pattern of DEE among wild birds.     

Service Sector Metabolism: Accounting for Energy Impacts of the Montjuic Urban Park in Barcelona

This article evaluates, from an industrial ecology (IE) perspective, the energy performance of the services inside an urban system and determines their global environmental impact. Additionally, this study determines which are the most energy demanding services and the efficiency of their energy use per visitor and per surface area unit.
The urban system under study is the Montjuïc urban park in Barcelona, Catalonia, Spain, which can be considered a services system. In this case study we distinguished the different patterns of consumption among the service fields and, by studying each field individually, found the most efficient facilities and identified the most critical services based on energy use per visitor or per square meter. These findings are based on the use of energy flow accounting (EFA), life-cycle assessment (LCA), and the energy footprint to analyze the Park's technical energy consumption.
Electricity consumption represents nearly 70% of the total energy consumed by the services at Montjuïc Park. The forest surface area required to absorb the CO2-equivalent emissions produced by the life cycle of the energy consumed at Montjuïc Park represents 12.2 times the Park's surface area. We conclude this article by proposing the incorporation of the methods of IE within the study of parks containing multiple services to improve energy management, and as a result, to raise the global environmental performance of the service sector.     

武汉市造纸行业资源代谢分析

资源代谢问题是造成产业系统生态环境影响的主要原因.在分析武汉市造纸行业资源代谢的基础上从资源输入-资源使用-环境胁迫-系统循环共生4个方面构建武汉市造纸行业资源代谢分析指标体系.运用模糊综合评判法和问题树模型对2007年武汉市造纸业的原材料、水、能源等资源的代谢与全国造纸行业平均水平进行了比较分析.结果表明:(1)武汉市造纸业资源代谢水平总体上评价等级为优,但某些指标与全国平均水平比还略有差距;(2)从资源输入角度分析,原材料输入生态效率及水资源输入生态效率等级为优,能源输入生态效率等级为良;(3)从资源使用角度分析,单位产品的原材料消耗及单位产品的水资源消耗等级为优,单位产品的能源消耗等级为良;(4)从环境胁迫角度分析,单位污染物工业总产值及单位产品污染物排放等级均为优,污染物达标排放率等级为良;(5)从系统循环共生分析,企业清洁生产达标率等级为良,资源持续利用及污染物治理等级为优,而中水回用率等级为差.通过代谢分析可得,武汉市造纸行业能源输入生态效率、单位产品能源消耗与全国平均水平比还有一定距离,整个行业中企业清洁生产比例还具有提升的空间;中水回用方面较弱,需要特别加强.     

Digital versus Print: Energy Performance in the Selection and Use of Scholarly Journals

Advances in digital technology and the growth of information networks are revolutionizing human activity. The Internet has been championed as a new tool for environmental improvement. A life-cycle energy analysis of digital libraries, a growing application of information technology, was conducted to test this premise.
Life-cycle models were compared for journal collections in digital and traditional formats. The basis for analysis was the amount of information in a typical scientific journal article (∼12 pages), which is equivalent to 0.97 hr of on-screen reading time. Digital system elements such as servers, routers, laser printers, and computer workstations were modeled. Journal production, delivery, storage, binding, interlibrary loan, and photocopying were examined for the traditional system. Building-related infrastructure, office paper, and personal transportation of the library patron were analyzed for both cases. In all, the study incorporated nearly 30 model elements, 90 input variables, and numerous fixed parameters.
Five primary scenarios were constructed to consider increasing levels of complexity. Scenario 1 assumes only one reading per article (unit of analysis). Additional scenarios assume 1,000 readings and vary the following: laser printing, photocopying, and personal transportation. Energy consumed by the digital collection ranged between 4.10 and 216 MJ. The traditional system realized burdens from 0.55 to 525 MJ. Four significant effects were uncovered: (1) Energy consumption per unit was highly influenced by the number of readings per article. (2) Networking infrastructure by itself had a relatively small effect on total energy consumed by the digital system. (3) When personal transportation was considered, its effects tended to dominate. (4) The impact of making personal copies varied. Photocopying always increased energy consumption, whereas laser printing actually saved energy when it substituted for on-screen reading.     

Ecological energetics of Central European grasshoppers (Orthoptera: Acrididae)

Summary Biomass and energy budgets and food utilization efficiencies of laboratory and wild populations of three Central European grasshopper species, Chorthippus parallelus (Zetterstedt), C. biguttulus (L.), and Gomphocerus rufus (L.), were studied between 1979 and 1984. Larval consumption is relatively low in C. biguttulus (C=4.3 kJ/ind.) compared with C. parallelus and G. rufus (4.9 kJ/ind.). In the adult phase (maturity) consumption rates of C. biguttulus and G. rufus (6.9 kJ/ind.) are similar, but higher in C. parallelus (7.3 kJ/ind.). The energy content decreases from the egg (23.2–24.3 J/mg dw) and body tissue (22.1–23.2 J/mg dw) to faeces (16.6–18.1 J/mg dw). The energy contents of faeces differ significantly between the species, indicating different rates of food conversion (on Dactylis glomerata). On average, the assimilation rates are about 30%, slightly lower in G. rufus. Approximate digestibility (A/C) ranges from 28.2 (G. rufus) to 35.7 (C. biguttulus) without great differences between larvae and adults. In contrast, the efficiency of conversion of ingested food (P/C) differs significantly between larval (10–11) and adult stages (3.4–3.6), and so to a much higher degree does the efficiency of conversion of digested food (P/A), from 30.3–33.5 in the larval to 9.5–14.9 in the adult period. Based on 5-year (C. parallelus) and 2-year studies (G. rufus) of the population dynamics and life tables, the energy budgets of wild populations were calculated and summarized into diagrams. Depending on the annually fluctuating densities, in both populations about 1%–2% of net primary production was consumed, and another 5%–9% was cut and dropped. The proportion of production of the grasshopper populations (body tissue) used for egg production differs in C. parallelus (28%) and G. rufus (44%). The energy cycling owing to energy storage in the living eggs amounts to 2%–3% of the total energy consumed by the population. The results are compared with the available data for grasshoppers in the literature.     

Immune activity elevates energy expenditure of house sparrows: a link between direct and indirect costs?

The activation of an immune response is beneficial for organisms but may also have costs that affect fitness. Documented immune costs include those associated with acquisition of special nutrients, as well as immunopathology or autoimmunity. Here, we test whether an experimental induction of the immune system with a non-pathological stimulant can elevate energy turnover in passerine birds. We injected phytohaemagglutinin (PHA), a commonly used mitogen that activates the cell-mediated immune response, into the wing web of house sparrows, Passer domesticus. We then examined energetic costs resulting from this immune activity and related those costs to other physiological activities. We found that PHA injection significantly elevated resting metabolic rate (RMR) of challenged sparrows relative to saline controls. We calculated the total cost of this immune activity to be ca. 4.20 kJ per day (29% RMR), which is equivalent to the cost of production of half of an egg (8.23 kJ egg(-1)) in this species. We suggest that immune activity in wild passerines increases energy expenditure, which in turn may influence important life-history characteristics such as clutch size, timing of breeding or the scheduling of moult.     

Using food for different purposes: female responses to prey in the predator Coccinella septempunctata L. (Coleoptera: Coccinellidae)

Abstract.  1. Although predatory insects often feed on diverse prey, their reproductive activity may be linked most strongly to a more restricted range of prey. The propensity of adult females of the ladybird beetle, Coccinella septempunctata L., to attack two natural prey species, pea aphids [ Acyrthosiphon pisum (Harris)] and alfalfa weevil larvae [ Hypera postica (Gyllenhal)], was compared, and the degree to which ladybird egg production depends on consumption of aphids vs. weevils was assessed.
2. Coccinella septempunctata females more readily attacked aphids than weevil larvae. This was true regardless of whether females had fed previously on aphids or on weevil larvae.
3. When females were provided with few to many aphids daily, or few aphids plus an excess number of weevil larvae, their rates of egg production depended primarily on the number of aphids consumed.
4. Addition of weevil larvae to diets of limited numbers of aphids increased egg production, but only modestly. Thus, consumption of weevil larvae may have served mostly for self-maintenance, thereby enabling females to use for egg production more of the nutrients and energy obtained from limited consumption of aphids.
5. The females' linkage of egg production primarily to aphid rather than weevil consumption may be adaptive, as their offspring are much less able as larvae to survive and mature on a diet of weevils rather than aphids.     

Nuptial food gifts influence female egg production in the scorpionfly Panorpa cognata

Abstract.  1. Before copulation, male Panorpa cognata scorpionflies offer females a salivary secretion, which is consumed by the female during copulation. It has previously been demonstrated that this nuptial food gift functions as mating effort by increasing male attractiveness and by increasing ejaculate transfer during copulation.
2. In this study, the effect of saliva consumption on female reproductive output was investigated, and thus the possibility that nuptial food gifts also serve as paternal investment. The experimental design enabled the effect of nuptial gift consumption to be disentangled from other possible effects of multiple mating or increased copula duration.
3. The results showed that saliva consumption increases female egg production by on average 8% (4.5 eggs) per consumed salivary mass, whereas mean egg weight was not influenced.4. These results have important implications for the evolution and maintenance of both male nuptial gifts and female polyandry in this and other species.     

Heat Production by the Denitrifying Bacterium Pseudomonas fluorescens and the Dissimilatory Ammonium-Producing Bacterium Pseudomonas putrefaciens during Anaerobic Growth with Nitrate as the Electron Acceptor

The heat production rate and the simultaneous nitrate consumption and production and consumption of nitrite and nitrous oxide were monitored during the anaerobic growth of two types of dissimilatory nitrate reducers. Pseudomonas fluorescens, a denitrifier, consumed nitrate and accumulated small amounts of nitrite or nitrous oxide. The heat production rate increased steadily during the course of nitrate consumption and decreased rapidly concomitant with the depletion of the electron acceptors. A mean experimental enthalpy change value of −800 kJ/mol of nitrate and a mean growth yield value of 33 g (dry weight)/mol of nitrate consumed were obtained for different concentrations of nitrate. For Pseudomonas putrefaciens, a dissimilatory ammonium producer, the nitrate consumption resulted in an accumulation of nitrite and nitrous oxide. Nitrite consumption commenced after depletion of the nitrate; consequently, two phases were noted in the heat production rate curve during growth. A mean experimental enthalpy change value of −810 kJ/mol of nitrate was obtained for different concentrations of nitrate.     

The effects of dietary nitrogen on reproductive development in the female boll weevil, Anthonomus grandis

ABSTRACT. The role of dietary nitrogen in reproductive development was investigated in the female boll weevil, Anthonomus grandis (Boh.)(Coleoptera: Curculionidae). Artificial diets were employed containing 1.7%, 2.6% and 4.0% N. Each diet was labelled with a ¹⁴C-amino acid mixture and standardized relative to cpm and N per mg of diet dry weight. Egg production, diet consumption, nitrogen consumption and nitrogen utilization were measured by recovering the cpm in the faeces, ovaries plus eggs and the carcass.
Females given the 4% N diet initiated oviposition on day 4 with maximum egg production of 11 eggs/day/female occurring on day 6. Females on the 2.6% N diet also initiated oviposition on day 4, but the time necessary to reach maximum egg production was extended. Egg production by these females eventually equalled the total production of the group on the 4% N diet. This was achieved by consuming more diet per female and dedicating a higher percentage of the absorbed diet to egg formation. With the 1.7% N diet, females showed both a delay and a decrease in total egg production because of reduced feeding and a reduced commitment of consumed nutrients to oöcyte maturation.
Switching dietary nitrogen concentrations after the initiation of oviposition resulted in changes in consumption and reproductive allocation within 48 h.     

STUDIES ON CELL METABOLISM AND CELL DIVISION : VI. OBSERVATIONS ON THE GLYCOGEN CONTENT,CARBOHYDRATE CONSUMPTION,LACTIC ACID PRODUCTION,AND AMMONIA PRODUCTION OF EGGS OF ARBACIA PUNCTULATA

1. Under the present conditions of experiment, Arbacia eggs were found to contain an average of 110 mg. of acid-hydrolyzable carbohydrate (calculated as glucose) per gm. of egg protein. This carbohydrate was almost all in the egg proper, little or none being found in the jelly. To permit conversion of the data to other bases of reference the relation of nitrogen content to wet and dry weight and to egg number were determined. The eggs were found to contain 23.9 per cent solids, 0.10 mg. nitrogen per mg. dry weight, and 5.93 mg. nitrogen per 10⁶ cells. From these results, about 7 per cent of the egg dry weight is acid-hydrolyzable carbohydrate and about 65 per cent is protein. 2. Approximately one-half of the total acid-hydrolyzable carbohydrate was isolated in the form of an alkali-stable, alcohol-precipitable carbohydrate. This substance gave a typical glycogen color test with iodine, yielded glucose on acid hydrolysis, and had, within the limits of experimental error, the same optical rotation as glycogen from other animal sources. Since known amounts of glycogen were completely recovered when carried through the isolation process, the nature of one-half of the acid-hydrolyzable carbohydrate of Arbacia eggs remains undetermined. 3. In order to gain some estimate of the extent to which Arbacia eggs utilize their total carbohydrate for development, determinations of the oxygen consumption, respiratory quotient, carbohydrate consumption, lactic acid production, and ammonia production were made. While all samples of eggs were found to utilize carbohydrate from the 15th to the 24th hours of development at 20°C., certain samples of eggs consumed little or no carbohydrate from the 1st to the 6th hours, the period during which cell division proceeds most rapidly. In a number of instances where carbohydrate breakdown was lacking, a substantial proportion of the oxygen consumption could be accounted for on the basis of processes involving oxidation of protein or protein breakdown products.     

Cost of egg production in the three-spined stickleback (Gasterosteus aculeatus L.)

In the interval between successive spawnings, female sticklebacks consumed approximately their own wet weight of Tubifex. On average, for 100 cal of food consumed, 26 cal of eggs, 3 cal of somatic growth and 11 cal of faeces were produced. In the absence of somatic growth, the efficiency of egg production was estimated as nearly 30%, and it was predicted that in the absence of egg production, the efficiency of somatic growth would range from 20% for a fish of 0.8 g wet weight to 3% for 2 g fish.
The weight of eggs produced at a spawning was a function of the weight of the female but not of the amount of food consumed. If food consumption was not sufficient to cover the cost of egg production, the fish lost weight. Total production (the summation of egg production and somatic growth) was a function of the amount of food consumed.     

Limitation of reproduction by feeding condition in a carabid beetle,Carabus yaconinus

1. Effects of the amount of food consumed on reproduction of the carabid beetle, Carabus yaconinus B., were studied in the laboratory by rearing beetles at different food levels, and the feeding and oviposition rates in the field were estimated on the basis of the relationships between the amount of food consumed, body weight and egg production obtained in the experiment.
2. The maximum amount of food consumed was 150 mg of minced beef per day. The number of eggs laid per day and the mean body weight increased with an increase in the amount of food consumed. High mortality occurred only when the beetles consumed less than 25 mg of minced beef per day.
3. The ratio of current body weight to the minimum one just before death by starvation, W/W_min, was used for the estimation of the rates of food consumption and egg production. The relationships between mean W/W_min ratio, the amount of food consumed and the number of eggs laid per day were clarified.
4. The relationships between ovary states (ovary weight and the number of mature eggs in the ovary) and W/W_min ratio were examined for the females caught in the field. Females with higher values of W/W_min ratio had more mature eggs.
5. The amount of food consumed by females in the field during the reproductive period was estimated to be 50–70% of the maximum value attained in the experiment and the estimated rate of oviposition was 45–59% of the maximum rate attained in the experiment.

     

Energetics and litter size variation in domestic dog Canis familiaris breeds of two sizes

We measured resting metabolic rate (RMR), daily energy expenditure (DEE) and metabolisable energy intake (MEI) in two breeds of dog during peak lactation to test whether litter size differences were a likely consequence of allometric variation in energetics. RMR of Labrador retrievers (30 kg, n=12) and miniature Schnauzers (6 kg, n=4) averaged 3437 and 1062 kJ/day, respectively. DEE of Labradors (n=6) and Schnauzers (n=4) averaged 9808 and 2619 kJ/day, respectively. MEI of Labradors (n=12) was 22448 kJ/day and of Schnauzers (n=7) was 5382 kJ/day. DEE of Labrador pups (2.13 kg, n=19) was 974 kJ/day and Schnauzers (0.89 kg, n=7) were 490 kJ/day. Although Labradors had higher MEIs than Schnauzers during peak lactation, there was no difference in mass-specific energy expenditure between the two breeds. Hence, it is unlikely that litter size variation is a likely consequence of differences in maternal energy expenditure. Individual offspring were relatively more costly for mothers of the smaller breed to produce. Therefore, litter size variations were consistent with the expectation that smaller offspring should be more costly for mothers, but not that smaller mothers should per se invest more resources in reproduction.     

Package Unit Size and Amount of Food: Do Both Influence Intake?

Objective: Large portions increase intake and are hypothesized to contribute to the obesity epidemic. However, it is unclear if portion size affects intake through changes in the unit size of available food or the overall amount of food available for consumption. Thus, this study examined the independent effects of package unit size and amount of food on intake. It was hypothesized that both variables would influence intake. Research Methods and Procedures: Non‐obese (BMI <30 kg/m²), non‐smoking, unrestrained, college‐aged men (n = 12) and women (n = 16) who regularly consumed (≥3 times/wk) snack foods were randomly assigned to one of four groups crossing package unit size (small vs. large) and amount of food (small vs. large). Participants were given a box with 4 snack foods (potato chips, cheese crackers, cookies, and candy) packaged according to their assigned group to take home and eat over 3 days. Dependent variables were energy and gram intake of provided snack foods. Results: An effect of amount of food was found (p < 0.01). A 100% increase in the amount of food provided produced an 81% increase in energy consumed from the snack foods [small amount, 21,037.6 ± 10,852 kJ (5028 ± 2596 kcal) vs. large amount, 11,640.7 ± 4914.1 kJ (2782 ± 1174 kcal)]. No effect of package unit size was found. Discussion: These results suggest that the amount of food available to eat strongly influences intake.     

Effect of reproductive state and body size on food consumption in captive Galago senegalensis braccatus

Measurements of food consumption for different types of foods were made for seven Galago senegalensis braccatus. Differences because of reproductive state in females and body size were found. Lactating females consumed more food in total and had greater energy and protein intake than they did during other reproductive states. Near-term pregnant females consumed less food, energy, and protein than they did during other reproductive states. Body size affected food intake, with smaller animals ingesting more per unit metabolic weight than larger subjects.     

How large an area of sea do Helgoland seabirds use for foraging during the breeding season?

Conclusions Of the species examined, only the guillemot remained within the study area, while other species ranged much further from the colony to forage. The number of guillemots present at sea was 2943±222 birds as calculated by Ordinary Kriging method (van der Meer & Leopold, in prep.). This corresponds to the number expected from the size of the colony and the attendance patterns of the birds (2889: Grunsky, 1992). Based on (1) metabolism of adults, (2) cost of egg production, (3) amount of food delivered to chicks, and (4) population parameters according to Grunsky (1992), we calculated the total energy consumption during the breeding season (cf. Cairns et al., 1992). The length of the breeding season was taken from 1st April (10 days before the first egg) to 16th June (mean day of leaving). In total, the guillemots used 1015 million kJ of energy to complete the 1991 breeding season. The diet (Grunsky, 1992) consisted, for 68.6%, of sandeel (7.8 kJ/g wet mass) and for 31.4%, of clupeoids (10.8 kJ/g), so in total 81 tonnes of sandeel and 37 tonnes of clupeoids were needed to support the colony of guillemots.     

Calorimetric study on human erythrocyte glycolysis. Heat production in various metabolic conditions.

The heat production of human erythrocytes was measured on a flow microcalorimeter with simultaneous analyses of lactate and other metabolites. The heat production connected with the lactate formation was about 17 kcal (71 kJ) per mol lactate formed which corresponded to the sum of heat production due to the formation of lactate from glucose and the heat production due to neutralization. The heat production rate increased as the pH of the suspension increased, corresponding to the increase in lactate formation. Glycolytic inhibitors such as fluoride and monoiodoacetate caused a decrease in the rate of heat production, whereas arsenate induced a large transient increase in heat production associated with a transient increase in lactate formation. Decrease in pyruvate concentration was usually associated with increase in heat production, although the decreased pyruvate concentration was coupled with formation of 2,3-bisphosphoglycerate. When inosine, dihydroxyacetone or D-glyceraldehyde was used as a substrate, an increase in the heat production rate was observed. Addition of methylene blue caused an oxygen uptake which was accompanied by a remarkable increase in heat production rate corresponding to about 160 kcal (670 kJ) per mol oxygen consumed. The value for heat production in red cells in the above-mentioned metabolic conditions was considered in relation to earlier known data on free energy and enthalpy changes of the different metabolic steps in the glycolytic pathway.     

Flux balance analysis of CHO cells before and after a metabolic switch from lactate production to consumption

Mammalian cell cultures typically exhibit an energy inefficient phenotype characterized by the consumption of large quantities of glucose and the concomitant production of large quantities of lactate. Under certain conditions, mammalian cells can switch to a more energy efficient state during which lactate is consumed. Using a metabolic model derived from a mouse genome scale model we performed flux balance analysis of Chinese hamster ovary cells before and after a metabolic switch from lactate production (in the presence of glucose) to lactate consumption (after glucose depletion). Despite a residual degree of freedom after accounting for measurements, the calculated flux ranges and associated errors were narrow enough to enable investigation of metabolic changes across the metabolic switch. Surprisingly, the fluxes through the lower part of the TCA cycle from oxoglutarate to malate were very similar (around 60 µmol/gDW/h) for both phases. A detailed analysis of the energy metabolism showed that cells consuming lactate have an energy efficiency (total ATP produced per total C‐mol substrate consumed) six times greater than lactate producing cells. Biotechnol. Bioeng. 2013; 110: 660–666. © 2012 Wiley Periodicals, Inc.