Intensive ground vegetation growth mitigates the carbon loss after forest disturbance

Aims

Slow or failed tree regeneration after forest disturbance is increasingly observed in the central European Alps, potentially amplifying the carbon (C) loss from disturbance. We aimed at quantifying C dynamics of a poorly regenerating disturbance site with a special focus on the role of non-woody ground vegetation.

Methods

Soil CO₂ efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration).

Results

Total soil CO₂ efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha^?1 yr.^?1). The undisturbed forest served as atmospheric C sink (2.1 t C ha^?1 yr.^?1), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (?5.5 t C ha^?1 yr.^?1) was almost twice as high as six years after disturbance (?2.9 t C ha^?1 yr.^?1), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss.

Conclusions

C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.

     

Modelling facilitation or competition within a root system: importance of the overlap of root depletion and accumulation zones

Background and aims

Relevant soil properties and nutrient distributions influencing crop root growth might be different under no-till (NT) and mouldboard plough (MP) management. The possible different root systems within different managements might have key impact on crop nutrient uptake and consequently crop production. Our objective was to assess the long-term combined effects of tillage and phosphorus (P) fertilization on corn (Zea mays L.) root distribution and morphology.

Methods

Corn root and soil samples were collected during the silking stage at five depths (0–5, 5–10, 10–20, 20–30 and 30–40 cm) and three horizontal distances perpendicular to the corn row (5, 15 and 25 cm) under MP and NT with three P fertilizations (0, 17.5, and 35 kg P ha^?1) for a long-term (22 years) experiment in eastern Canada. Root morphology and soil properties were determined.

Results

NT practice decreased corn root biomass by ?26 % compared to MP, mainly by decreasing the primary and secondary roots. Additionally, corn roots in NT tend to be more expansive on the surface layer with higher root length and surface densities for the depth of 0–5 cm at two sampling distances of 15 and 25 cm. The 35 kg P ha^?1 rate increased the root biomass by 26 and 41 % compared to the 0 and 17.5 kg P ha^?1 rates.

Conclusions

No-tillage practice and low rates of P fertilization reduce corn roots. This is probably caused by the weed competition in NT and the continued downward P status with low P rates over 22 years.

     

Improving N management through intercropping alleviates the inhibitory effect of mineral N on nodulation in pea

Background and aims

Symbiotic N₂ fixation is essential in the development of sustainable agriculture, but the nodulation of legumes is usually inhibited by N fertilization. Here, the intercropping of maize and pea in strips under various N managements was used as a means to alleviate the inhibitory effect of mineral N on pea nodulation and N₂ fixation and to improve system performance.

Methods

N natural abundance (δ ¹⁵N) analysis was employed to quantify N₂ fixation in the 3 years (2012 to 2014) of field experiment in Hexi Corridor of Northwestern China. Four N management systems with N rate of 0 kg N ha^?1 (the control), 90?+?45 kg N ha^?1 (base N plus topdressing N), 90?+?90 kg N ha^?1, and 90?+?135 kg N ha^?1 were implemented in the maize/pea strip intercropping to form different ratios of base N to topdressing N.

Results

Intercropped pea improved nodule biomass per plant by 99 %, increased nitrogen derived from the atmosphere (Ndfa) by 35 %, and promoted aboveground plant tissue N accumulation by 35 % as compared with sole pea, averaged across the four N treatments. Compared to the highest N fertilizer treatment, a reduction of topdressing to 45 kg N ha^?1 increased the nodule biomass of intercropped pea by 116 %, Ndfa by 35 %, and grain yield by 6 %.

Conclusions

Adaptation of suitable N management in cereal/legume intercropping systems will allow an effective conversion of atmospheric N₂ into crop available N and thus maximizing the system productivity.

     

The fate of fertiliser P in soil under pasture and uptake by subterraneum clover – a field study using <Superscript>33</Superscript>P-labelled single superphosphate

Background and aims

Single superphosphate (SSP) is a major source of phosphorus (P) used in grazing systems to improve pasture production. The aim of this experiment was to determine the fate of fertiliser P in clover pastures under field conditions.

Methods

A procedure was developed to radiolabel SSP granules with a ³³P radiotracer, which was then applied to the soil surface (equivalent to ~12 kg P ha^?1) of a clover pasture. Recovery of fertiliser P was determined in clover shoots, fertiliser granules and soil fractions (surface layer: 0–4 cm and sub-surface layer: 4–8 cm).

Results

The P diffusion patterns of the ³³P-labelled SSP granules were not significantly different to those of commercial SSP granules (P?>?0.05). Recovery of fertiliser P in clover shoots was 30–35 %. A considerable proportion of the fertiliser P (~28 %) was recovered in the surface soil layer and was largely inorganic P.

Conclusions

Recovery of fertiliser P by clover plants was up to 35 % in the year of application. Much of the fertiliser P in soil fractions was inorganic P, which highlights the importance of inorganic P forms and dynamics in soils under clover pasture on a single season timeframe at these sites.

     

Changes from pasture to a native tree plantation affect soil organic matter in a tropical soil,Panamá

Background and aims

We examined changes in soil organic matter arising from conversion of a 45-year old pasture to a 10 yr. old native tree plantation in Panamá, to evaluate the effect of monoculture and mixtures.

Methods

We intensively sampled the soil 0–10 cm depth in the pasture in 2001 and in 22 plantation plots in 2011, ranging from 5 monocultures to 3- and 6-species treatments; samples were also taken from an undisturbed forest site. Soil analyses included organic carbon (SOC) and δ¹³C.

Results

Conversion of the pasture to tree plantation resulted in an overall loss of SOC of 0.6 kg m^?2 (18%) in the top 10 cm, but neither tree species nor diversity had a significant effect. End-member δ¹³C values suggested that the contribution of C₃ plants to SOC was increased from 26% in the pasture to 55% after 10 years of plantation and SOC turnover times were calculated to be 21–36 yr.

Conclusions

The magnitude of the loss in soil SOC is smaller than the increases in tree biomass (~3 kg C m^?2) and litter (~0.3 kg C m^?2) in the plantation, but still a significant part of the ecosystem C balance.

     

Opportunities for mobilizing recalcitrant phosphorus from agricultural soils: a review

Background

Phosphorus (P) fertilizer is usually applied in excess of plant requirement and accumulates in soils due to its strong adsorption, rapid precipitation and immobilisation into unavailable forms including organic moieties. As soils are complex and diverse chemical, biochemical and biological systems, strategies to access recalcitrant soil P are often inefficient, case specific and inconsistently applicable in different soils. Finding a near-universal or at least widely applicable solution to the inefficiency in agricultural P use by plants is an important unsolved problem that has been under investigation for more than half a century.

Scope

In this paper we critically review the strategies proposed for the remobilization of recalcitrant soil phosphorus for crops and pastures worldwide. We have additionally performed a meta-analysis of available soil ³¹P–NMR data to establish the potential agronomic value of different stored P forms in agricultural soils.

Conclusions

Soil inorganic P stocks accounted on average for 1006 ± 115 kg ha^?1 (57 ± 7%), while the monoester P pool accounted for 587 ± 32 kg ha^?1 (33 ± 2%), indicating the huge potential for the future agronomic use of the soil legacy P. New impact driven research is needed in order to create solutions for the sustainable management of soil P stocks.

     

<Emphasis Type="Italic">Gluconacetobacter diazotrophicus</Emphasis> exopolysaccharide protects bacterial cells against oxidative stress in vitro and during rice plant colonization

Aims

Increasing the input and turnover of root tissue is considered to be one method that may increase carbon (C) inputs and storage in soil. The use of herbicide during pasture renewal (periodic re-sowing of pasture) is expected to increase root inputs and turnover as plants die. The objective of this study was to quantify the short-term impact of pasture renewal on root turnover and C input to soil of ryegrass-clover pastures.

Methods

Pastures were labelled in the field using a ¹³C isotope pulse labelling method within 1 m² clear chambers. Five daily labelling events were carried out during one week in paired treatment plots within 3 replicate paddocks. One plot per paddock was sprayed with herbicide and then the pasture was renewed by direct drilling of seed. The ¹³C of roots and soil (0–100 mm) was measured at regular intervals over an 89-day period.

Results

Herbicide application caused an initial rapid turnover time of 17 days followed by a slower turnover time of 524 days, compared to unsprayed pasture which had a root turnover of 585 days. Faster root turnover following herbicide application resulted in greater cumulative C input to soil over 89 days with approximately double the C input in the sprayed treatment (3238 ± 378 kg C ha^?1) compared to the unsprayed treatment (1726 ± 540 kg C ha^?1).

Conclusions

The use of glyphosate during pasture renewal increased root turnover and resulted in a greater short term cumulative C input to soil. This study provides the first values of root turnover and C input to soil during a pasture renewal event in New Zealand pasture systems and contributes to the understanding of how pasture roots may influence the soil C input following plant death in grassland systems.

     

Variety specific relationships between effects of rhizobacteria on root exudation,growth and nutrient uptake of soybean

Aims

It has been increasingly recognized that only distal lower order roots turn over actively within the <2 mm fine root system of trees. This study aimed to estimate fine root production and turnover rate based on lower order fine roots and their relations to soil variables in mangroves.

Methods

We conducted sequential coring in five natural mangrove forests at Dongzhai Bay, China. Annual fine root production and turnover rate were calculated based on the seasonal variations of the biomass and necromass of lower order roots or the whole fine root system.

Results

Annual fine root production and turnover rate ranged between 571 and 2838 g m^?2 and 1.46–5.96 yr^?1, respectively, estimated with lower order roots, and they were increased by 0–30 % and reduced by 13–48 %, respectively, estimated with the whole fine root system. Annual fine root production was 1–3.5 times higher than aboveground litter production and was positively related to soil carbon, nitrogen and phosphorus concentrations. Fine root turnover rate was negatively related to soil salinity.

Conclusions

Mangrove fine root turnover plays a more important role than aboveground litter production in soil C accumulation. Sites with higher soil nutrients and lower salinity favor fine root production and turnover, and thus favor soil C accumulation.

     

Simulated nitrogen deposition significantly suppresses the decomposition of forest litter in a natural evergreen broad-leaved forest in the Rainy Area of Western China

Background and aims

Litter, an essential component of forest ecosystems, plays an important role in maintaining soil fertility, sequestering carbon (C) and improving soil biodiversity. However, litter decomposition is affected by increased nitrogen (N) deposition. Numerous reports have presented N deposition experiments in different forest ecosystems to investigate the effects of N deposition on litter decomposition, but the effects remain unclear, especially in ecosystems receiving increasingly higher levels of ambient N deposition. To address this gap, we performed a litterbag experiment to understand the effects of increasing N deposition on the litter decomposition process in natural evergreen broad-leaved forest in the Rainy Area of Western China.

Methods

A 2-year field litter decomposition experiment was conducted using the litterbag method. Four levels of N deposition were established: control (CK; 0 kg·N·ha^?1·year^?1), low N deposition (LN; 50 kg·N·ha^?1·year^?1), medium N deposition (MN; 150 kg·N·ha^?1·year^?1), and high N deposition (HN; 300 kg·N·ha^?1·year^?1). The simulated N depositions ranged from 50% to 320% of the ambient rate of wet N deposition.

Results

Simulated N deposition significantly increased the remaining mass, C, N, lignin and cellulose of the litter. The LN treatment decreased the remaining phosphorus (P); conversely, the HN treatment increased it. In the late stage of the study period, the mass remaining was positively closely correlated to the lignin and cellulose remaining during the decomposition process.

Conclusions

Simulated N deposition significantly suppressed the litter decomposition in the natural evergreen broad-leaved forest, despite the high rate of ambient N deposition, and the inhibitory effects increased with the N deposition levels. The suppressive effect of N deposition on litter decomposition may be primarily explained by the inhibition of lignin and cellulose degradation by the exogenous inorganic N. With ongoing N deposition in future, N deposition may have a potentially significant impact on C and N cycles in such forest ecosystems.

     

Responses of switchgrass soil respiration and its components to precipitation gradient in a mesocosm study

Aims

The objective of this study was to investigate the effects of the precipitation changes on soil, microbial and root respirations of switchgrass soils, and the relationships between soil respiration and plant growth, soil moisture and temperature.

Methods

A mesocosm experiment was conducted with five precipitation treatments over two years in a greenhouse in Nashville, Tennessee. The treatments included ambient precipitation, ?50%, ?33%, +33% and +50% of ambient precipitation. Soil, microbial, and root respirations were quantified during the growing seasons.

Results

Mean soil and root respirations in the +50% treatment were the highest (2.48 and 0.93 μmol CO₂ m^?2 s^?1, respectively) among all treatments. Soil microbial respiration contributed more to soil respiration, and had higher precipitation sensitivity mostly than root respiration. Increases in precipitation mostly enhanced microbial respiration while decreases in precipitation reduced both microbial and root respirations. Across precipitation treatments, soil respiration was significantly influenced by soil moisture, soil temperature, and aboveground biomass.

Conclusions

Our results showed that microbial respiration was more sensitive to precipitation changes, and precipitation regulated the response of soil respiration to soil temperature. The information generated in this study will be useful for model simulation of soil respiration in switchgrass fields under precipitation changes.

     

Impact of plant growth-promoting bacteria on grain yield,protein content,and urea-<Superscript>15</Superscript> N recovery by maize in a Cerrado Oxisol

Background and aims

The inoculation of cereal crops with plant growth-promoting bacteria (PGPB) is a potential strategy to improve fertilizer-N acquisition by crops in soils with low capacity to supply N. A study was conducted to assess the impact of three inoculants on grain yield, protein content, and urea-¹⁵ N recovery in maize (Zea mays L.) under Cerrado soil and climate conditions.

Methods

The main treatments included inoculants containing (i) Azospirillum brasilense strain Sp245, (ii) A. brasilense strains AbV5 + AbV6, (iii) Herbaspirillum seropedicae strain ZAE94, and (iv) a non-inoculated control. The subtreatments were (i) urea-N fertilization (100 kg N ha^?1) at 30 days after sowing and (ii) no N addition at the stage. To determine fertilizer-N recovery, ¹⁵N–labelled urea was applied in microplots.

Results

Inoculants carrying A. brasilense improved urea-¹⁵ N acquisition efficiency in maize and also improved grain yield compared to the non-inoculated control, while urea-N fertilization enhanced grain quality by providing higher protein content.

Conclusion

Our results suggest that the inoculation of maize grains with PGPB represents a strategy to improve fertilizer-N recovery and maize yield in Cerrado soil with a low capacity to supply N.

     

Production of a therapeutic protein by fusing it with two fragments of the carboxyl-terminal peptide of human chorionic gonadotropin β-subunit in <Emphasis Type="Italic">Pichia pastoris</Emphasis>

Objective

To produce a therapeutic protein (endostatin) by fusion with two fragments of the carboxyl-terminal peptide (CTP) of the human chorionic gonadotropin β-subunit in Pichia pastoris.

Results

Two CTP sequences were fused to the C-terminal of human endostatin, and the fusion protein (endo-CTP) was expressed by P. pastoris. Endo-CTP inhibited proliferation of endothelial cells with an IC₅₀ of 7 μg ml^?1, and 30 % of cells were annexin V-positive after treatment with 20 μg endo-CTP ml^?1 for 48 h. Migration of endothelial cells was inhibited by endo-CTP in a concentration-dependent manner. The half-life of endo-CTP in Sprague–Dawley rats was much longer than that of its commercial counterpart (Endostar).

Conclusion

A long-acting endostatin can be produced using CTP technology.

     

Macropore effects on phosphorus acquisition by wheat roots – a rhizotron study

Background and aims

Macropores may be preferential root pathways into the subsoil. We hypothesised that the presence of macropores promotes P-uptake from subsoil, particularly at limited water supply in surface soil. We tested this hypothesis in a rhizotron experiment with spring wheat (Triticum aestivum cv. Scirocco) under variation of fertilisation and irrigation.

Methods

Rhizotrons were filled with compacted subsoil (bulk density 1.4 g cm^?3), underneath a P-depleted topsoil. In half of these rhizotrons the subsoil contained artificial macropores. Spring wheat was grown for 41 days with and without irrigation and ³¹P–addition. Also, a ³³P–tracer was added at the soil surface to trace P-distribution in plants using liquid scintillation counting and radioactive imaging.

Results

Fertilisation and irrigation promoted biomass production and plant P-uptake. Improved growing conditions resulted in a higher proportion of subsoil roots, indicating that the topsoil root system additionally promoted subsoil nutrient acquisition. The presence of macropores did not improve plant growth but tended to increase translocation of ³³P into both above- and belowground biomass. ³³P–imaging confirmed that this plant-internal transport of topsoil-P extended into subsoil roots.

Conclusions

The lack of penetration resistance in macropores did not increase plant growth and nutrient uptake from subsoil here; however, wheat specifically re-allocated topsoil-P for subsoil root growth.

     

Secondary metabolites released into the rhizosphere by <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> and <Emphasis Type="Italic">Fusarium</Emphasis> spp. as underestimated component of nonspecific replant disease

Background and aims

A study was performed to investigate the role of fungal metabolites released into the rhizosphere of replanted orchards as a potential biotic component of tree growth decline.

Methods

The phytotoxicity of the gamma ray-sterilized crude culture filtrates of sixteen fungal species originating from replanted apple orchards was tested in a bioassay. Low molecular weight compounds released by Fusarium spp. were analyzed.

Results

The fungal culture filtrates affected seedling growth and health with an activity that varied from growth inhibition to promotion. Three out of the six species of Fusarium tested produced species-specific mycotoxins such as equisetin and enniatin B and D (<1 μg ml^?1 and <6 μg ml^?1, respectively) associated with root-tip necrosis, whereas fusaric acid (80–230 μg ml^?1) was associated with asymptomatic plant growth inhibition. These findings were consistent with those obtained using pure compounds. Moreover, methoxyconidiol, paecilaminol, integrastatin B and other biologically active compounds, whose fungal origin and phytotoxicity have not yet been reported, were found. in all fungal filtrates.

Conclusions

Findings suggest that i) phytopathogenicity of soil borne fungi can be expressed regardless of root infection; ii) a synergistic interaction between co-occurring mycotoxins and other biologically active compounds may explain plant growth inhibition. Iii) fungal metabolites released into soil may represent an underestimated component of nonspecific replant disease.

     

<Emphasis Type="Italic">Mesorhizobium jarvisii</Emphasis> sv. astragali as predominant microsymbiont for <Emphasis Type="Italic">Astragalus sinicus</Emphasis> L. in acidic soils,Xinyang, China

Background and aims

Common bean (Phaseolus vulgaris L.) nodulates with a wide range of rhizobia. Amongst these is Bradyrhizobium, which is inefficient but able to induce profuse nodulation on this crop. Based on this observation, we tested whether co-inoculating bradyrhizobia with a more standard common bean symbiont, Rhizobium tropici, could stimulate growth and nodulation of common bean, thus contributing to a more effective symbiosis.

Methods

Rhizobium tropici was co-inoculated with two Bradyrhizobium strains applied at three different doses (10⁴, 10⁶, and 10⁸ CFU seed^?1) under sterile conditions, and at a single dose (10⁸ CFU seed^?1) in non-sterile soil. Plant biomass, nodulation, and N accumulation in plant tissues were evaluated.

Results

Co-inoculated plants produced more nodules, and accumulated more shoot dry biomass and nitrogen than plants inoculated with R. tropici alone under gnotobiotic conditions. Significant responses were observed at the highest inoculum dose and a significant correlation between dose and shoot dry weight was observed. Co-inoculation increased biomass and N accumulation in non-sterile soil, although with a smaller magnitude.

Conclusions

Altogether, our findings suggest that the co-inoculation with bradyrhizobia contributed to an improved symbiotic interaction between R. tropici and common beans.

     

High-yield production of pure tagatose from fructose by a three-step enzymatic cascade reaction

Objective

To produce tagatose from fructose with a high conversion rate and to establish a high-yield purification method of tagatose from the reaction mixture.

Results

Fructose at 1 M (180 g l^?1) was converted to 0.8 M (144 g l^?1) tagatose by a three-step enzymatic cascade reaction, involving hexokinase, plus ATP, fructose-1,6-biphosphate aldolase, phytase, over 16 h with a productivity of 9 g l^?1 h^?1. No byproducts were detected. Tagatose was recrystallized from ethanol to a purity of 99.9% and a yield of 96.3%. Overall, tagatose at 99.9% purity was obtained from fructose with a yield of 77%.

Conclusion

This is the first biotechnological production of tagatose from fructose and the first application of solvent recrystallization for the purification of rare sugars.

     

Responses of rice to chronic and acute iron toxicity: genotypic differences and biofortification aspects

Background and aims

Iron (Fe) toxicity is a wide-spread stress in lowland rice production. The aim of this study was to differentiate between responses to acute Fe stress during the vegetative stage and chronic Fe stress throughout the growing period.

Methods

Six rice genotypes were tested in a semi-artificial greenhouse setup, in which acute (almost 1500 mg L^?1 Fe in soil solution during the vegetative stage) and chronic (200 to 300 mg L^?1 Fe throughout the season) Fe toxicity were simulated.

Results

Acute Fe stress induced early development of heavy leaf bronzing, whereas moderate symptoms occurred in the chronic treatment throughout the season. Grain yields were only reduced in the chronic stress treatment (?23 %) due to reductions in spikelet fertility, grain number and grain weight. Symptom formation during the early growth stages did not reflect yield responses in all genotypes. Only one genotype showed increases in grain Fe concentrations (24 % in the acute stress and 44 % in the chronic stress) compared to the control.

Conclusions

Contrasting genotypes responded differently to acute and chronic Fe toxicity, and one genotype showed consistent tolerance and the ability to translocate excess Fe into grains. These traits can be useful in the adaptive breeding of rice for Fe toxic environments.

     

Characterization of a novel asparaginase from soil metagenomic libraries generated from forest soil

Objectives

To screen soil metagenomic libraries for novel enzymes with enhanced activities.

Results

To screen soil metagenomic libraries for novel enzymes with enhanced activities. A novel l-asparaginase was identified from forest soil metagenome and its characteristics were studied. The purified protein had a specific activity of 696 IU mg^?1 and optimum activity at pH 7 and 35 °C. Enhanced enzyme activities were observed in the presence of Mg²⁺, Ca²⁺ and K⁺. The K_m value, 2 mM, and enzyme specificity constant 7.7 mM^?1s^?1 indicated that the recombinant enzyme has good substrate affinity to l-asparagine compared with commercially-available Escherichia coli asparaginase. The IC₅₀ value of 0.78 µg ml^?1 (0.47 IU ml^?1) was observed with HL60 cell line and 0.39 µg ml^?1(0.23 IU ml^?1) with MOLT-3 and MOLT-4 cell lines, which is better than that of commercially-available drugs.

Conclusion

The soil metagenome derived l-asparaginase with enhanced activities could be a potential candidate to develop as a drug in Acute Lymphoblastic Leukemia (ALL) therapy.

     

Pranlukast,a novel binding ligand of human Raf1 kinase inhibitory protein

Objectives

To study the binding of pranlukast to hRKIP and its regulatory role in the Raf1/MEK/ERK signal pathway.

Results

NMR and fluorescence experiments demonstrated hRKIP could bind pranlukast with a binding constant of 1016 mM^?1. Residues (Y81, S109 and Y181) on the conserved ligand-binding pocket of hRKIP played a crucial role in binding pranlukast, and their mutations reduced the binding affinity more than 85 %. Furthermore, 25 μM pranlukast could up-regulate the ERK phosphorylation by about 17 %.

Conclusion

Pranlukast may be used as a potential drug precursor for treating hRKIP involved diseases.

     

Production of δ-decalactone from linoleic acid via 13-hydroxy-9(Z)-octadecenoic acid intermediate by one-pot reaction using linoleate 13-hydratase and whole <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> cells

Objective

To produce δ-decalactone from linoleic acid by one-pot reaction using linoleate 13-hydratase with supplementation with whole Yarrowia lipolytica cells.

Results

Whole Y. lipolytica cells at 25 g l^?1 produced1.9 g l^?1 δ-decalactone from 7.5 g 13-hydroxy-9(Z)-octadecenoic acid l^?1 at pH 7.5 and 30 °C for 21 h. Linoleate 13-hydratase from Lactobacillus acidophilus at 3.5 g l^?1 with supplementation with 25 g Y. lipolytica cells l^?1 in one pot at 3 h produced 1.9 g l^?1 δ-decalactone from 10 g linoleic acid l^?1 via 13-hydroxy-9(Z)-octadecenoic acid intermediate at pH 7.5 and 30°C after 18 h, with a molar conversion yield of 31 % and productivity of 106 mg l^?1 h^?1.

Conclusion

To the best of our knowledge, this is the first production of δ-decalactone using unsaturated fatty acid.