Understanding the human impact on Akita-sugi cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) forest in the late Holocene through pollen analysis of annually laminated sediments from Ichi-no-Megata,Akita, Japan

Akita-sugi (Cryptomeria japonica, Japanese cedar that is grown in Akita) forests are among the most important for commercially valuable timber in Japan. Historically, these forests have been severely exploited, although now some parts of them are conserved. It is important to know the detailed history of the forests in order to utilize them sustainably in the future. This study analyzes the pollen in an annually laminated lake sediment core from Ichi-no-Megata on the Oga peninsula, Akita, Japan, to understand the history of Akita-sugi cedar forests. An age-depth model was developed based on the results of an accelerator mass spectrometer dating of 13 plant macrofossils from the surface to 422 cm in depth, the Towada-a tephra and other well-known event layers. The dominant pollen taxa were Cryptomeria and Fagus crenata by ad 1000. The first increase of Cryptomeria was detected around 1700 bc. By the 1st century ad, Cryptomeria forest was established. At that time, Cryptomeria was mixed with deciduous trees, mainly F. crenata. The pollen analysis found evidence that the main loss of woodland occurred during the 11th century ad, when forest lands were cleared for agriculture. Substantial natural forests nevertheless remained until the 16th century, after which forest resources were exhausted. Conservation and plantation activities took place later, but human activity in response to severe famines prevented the recovery of the forests. After the famine periods, the remaining forests recovered to their previous condition, but after World War II, the natural forests shrank further and plantation forests without deciduous trees were established over large areas.     

Unravelling the past 1,000 years of history of human–climate–landscape interactions at the Lindu plain,Sulawesi, Indonesia

The Lindu plain, located in the northern mountainous region of the Lore Lindu National Park in Sulawesi, Indonesia, provides many ecosystem services for the population inhabiting the area and harbours a unique biodiversity. Palynological, charcoal and diatom analyses of a lake sediment core from Lake Lindu (Danau Lindu) reveal that during the last 1,000 years the Lindu plain has been modified by human activities. Evidence of frequent burning and possible shifting cultivation from an earlier phase from ca. ad 1000 to 1200 might be related to the metal age population which erected the megaliths in the province of Central Sulawesi. From ca. ad 1200–1700 there followed 500 years of wetter climate conditions, corresponding to the southward movement of the Intertropical Convergence Zone. At the same time, decreases of macro-charcoal concentrations and pioneer vegetation indicators show that the use of the landscape of Lindu plain had become more permanent. Following a phase of forest recovery from ca. ad 1730 to 1910, the most recent part of the Lake Lindu record shows a trend towards deforestation that started in the late 20th century, lasting until now. The lake level started to fall at the beginning of the 20th century, as shown by the increase of sedimentation rate and supported by low pollen concentration and palaeomagnetic data. Such a change was unprecedented for the last 1,000 years covered by the record, and it has no link to the climate variability as reconstructed for the last hundred years. If deforestation increases and a larger amount of water is channelled away from the lake for irrigation purposes, the lake level will continue to fall. This suggests that there is a need for better management of the forests surrounding the plain and of the irrigation systems in the area open for cultivation.     

Investigation of peat sediments from Daiyun Mountain in southeast China: late Holocene vegetation,climate and human impact

In this study, late Holocene vegetation, climate and human impacts were investigated using multiproxy data-pollen percentages, pollen accumulation rates (PAR), humification and loss-on-ignition (LOI)—measured from peat sediments from Daiyun Mountain, southeast China. A stratigraphic chronology was established on the basis of four radiocarbon dates. The 4,350 year sequence of vegetation history and climate change exhibits three distinctive stages: (1) 4,350–1,000 cal bp, during which the vegetation was dominated by evergreen forests mainly composed of broad-leaf trees, indicating a warm and wet climate; (2) 1,000–550 cal bp, during which the climate was thought to be cool and dry, based on a decrease in pollen percentages and the PARs of trees, shrubs and wetland herbs, and an increase in the pollen percentage and PAR of dry land herbs, as well as high overall LOI values; and (3) 550 cal bp to modern times, during which higher pollen percentages of dry land and wetland herbs, along with low pollen percentage and PAR of trees and shrubs, as well as low absorbance and LOI values, suggest relatively cooler but wetter climate conditions. In addition, major climatic events, such as the warm period from ad 670–960, the Medieval Warm Period (ad 1050–1520) and the Little Ice Age (ad 1580–1850), could be identified within the peat sediments in this study, with climatic conditions at these times being characteristically warm and wet, warm and dry, and cold and wet, respectively. Pollen signals indicate significant human impact since 1,000 cal bp, which may be linked to the development of the local porcelain industry and a rapid increase in the population in the study region.     

Boreal forest dynamics in north-eastern Sweden during the last 10,000 years based on pollen analysis

A pollen record obtained from a 2.2-m sediment succession deposited in a small lake in the province of Västerbotten, north-eastern Sweden, reveals the presence of continuous forest cover since 8,500 calendar years before present (cal b.p.). Forest with abundant Pinus (pine) and Betula (birch) initially colonized the area, followed by a dominance of deciduous trees, primarily Betula, from ca. 8,000 to ca. 3,200 cal b.p. Pollen accumulation rates of Quercus (oak), Ulmus (elm) and Tilia (linden) suggest the possible local presence of these thermophilous tree species during this period. The climate gradually became colder and moister around 3,500 cal b.p. and an increased abundance of Sphagnum spores indicates paludification. Picea (spruce) became established around 3,200 cal b.p. and less than 500 years later this was the dominant tree species around the lake. The fire frequency as inferred from charcoal particles exhibits a general increase from ca. 3,000 cal b.p. with subsequent charcoal accumulation maxima at around 2,800 cal b.p., 1,700 cal b.p. and in recent time. The human influence on vegetation was significant during the last 200–300 years. Soil erosion increased substantially and fern spores amount to ca. 55% of the total pollen assemblage in the uppermost samples. These results suggest an extensive anthropogenic impact on the local forest ecosystem, with abundant logging, burning and ditching in the vicinity of the lake. Independent evidence of sub-recent human-induced environmental change is provided by historical accounts. Complementary information on catchment soil development and aquatic nutrient status was provided by records of magnetic susceptibility and elemental carbon, and nitrogen contents obtained from the same sediment core.     

Seven Millennia of human impact as reflected in a high resolution pollen profile from the profundal sediments of Litzelsee,Lake Constance region,Germany

A profundal core from Litzelsee, a small cirque lake in the western Lake Constance region, was investigated by pollen analysis and dated radiometrically. The upper part of the core, chronologically between 5000 cal bc and 1850 ad, was sampled continuously, resulting in a total of 449 samples, each with a sum of 1,000 arboreal pollen grains. Also in this huge data set, rare taxa, normally lacking or very scarce in pollen profiles, were registered. The ecological evaluation of these, with a focus on anthropogenic indicators, sheds light on environmental and human impact history from the Neolithic to Modern times. Further, the results are put in a regional context, together with seven other mostly unpublished pollen profiles studied in the same way.     

Late Holocene landscape development around a Roman Iron Age mass grave,Alken Enge,Denmark

Sediments from the small lake Ilsø situated in the Illerup/Alken Enge Valley were studied in order to investigate past landscape development at the time of a probably ritual human mass burial following battle during the Roman Iron Age (ad 1–400). A pollen record from Ilsø and a number of other records from Jutland were combined using the Landscape Reconstruction Algorithm to reconstruct local vegetation changes through the last 2,800 years. These methods were supplemented by studies of catchment-related geochemistry of the Ilsø lake sediments. The results show a marked reforestation event associated with a strong decrease in erosion levels at the very beginning of the first century ad, contemporaneous with the finds of human remains at Alken Enge. Comparison with a pollen record 10 km away and with those from other sites, reveals that this reforestation occurs unusually early and rapidly, and is an unparalleled development in a Danish context. We suggest that the major landscape changes at the beginning of the Roman Iron Age and forest cover for the next few centuries comprise a possible example of ritual control of local land-use.     

Vegetation and environment of the Rødalen alpine area, Central Norway, with emphasis on the early Holocene

Detailed pollen analysis and pine megafossils from the immediate area of Rødalen in Central Norway have revealed new knowledge of Holocene alpine environments. A period of about 1,000 years characterised by pioneer herbs, dwarf-shrubs (Betula nana, Empetrum) and Juniperus followed the Holocene climatic amelioration. Local birch forest became established around 10.3 ka b.p., ca 150 years earlier than the local pine rise. Pine dominated at 1,100 m a.s.l. from 9.9 to 8.5 ka b.p., followed by birch forests until 1.3 ka b.p. when deforestation occurred. Slightly after 6 ka b.p., pine forests disappeared from the valley floor (930 m a.s.l.), an area that today is dominated by birch forest. Three short-lasting vegetational set-backs at ca 10.7, 10.5 and 10.3 ka b.p. may indicate climate oscillations. A temporary reduction of local forests reflects the Erdalen 2/9.7 ka b.p. event. The influence of the 8.2 event, superimposed on a cooling trend, lasted ca 400 years and involved a two-step vegetational regression: (1) A strong reduction of pine forests due to cooling and (2) reduction of alder due to cold and drought. Winter stress preventing pine regeneration may have caused scarcity of pine megafossils from the latter period. In the early Holocene, vegetation in the present alpine region was not in equilibrium with temperature development. It is suggested that the birch forest establishment lagged by about 1,000 years due to drought, whereas winter stress may have delayed the establishment of pine even longer.     

Vegetation and fire history of coastal north-eastern Sardinia (Italy) under changing Holocene climates and land use

Little is known about the vegetation and fire history of Sardinia, and especially the long-term history of the thermo-Mediterranean belt that encompasses its entire coastal lowlands. A new sedimentary record from a coastal lake based on pollen, spores, macrofossils and microscopic charcoal analysis is used to reconstruct the vegetation and fire history in north-eastern Sardinia. During the mid-Holocene (c. 8,100–5,300 cal bp), the vegetation around Stagno di Sa Curcurica was characterised by dense Erica scoparia and E. arborea stands, which were favoured by high fire activity. Fire incidence declined and evergreen broadleaved forests of Quercus ilex expanded at the beginning of the late Holocene. We relate the observed vegetation and fire dynamics to climatic change, specifically moister and cooler summers and drier and milder winters after 5,300 cal bp. Agricultural activities occurred since the Neolithic and intensified after c. 7,000 cal bp. Around 2,750 cal bp, a further decline of fire incidence and Erica communities occurred, while Quercus ilex expanded and open-land communities became more abundant. This vegetation shift coincided with the historically documented beginning of Phoenician period, which was followed by Punic and Roman civilizations in Sardinia. The vegetational change at around 2,750 cal bp was possibly advantaged by a further shift to moister and cooler summers and drier and milder winters. Triggers for climate changes at 5,300 and 2,750 cal bp may have been gradual, orbitally-induced changes in summer and winter insolation, as well as centennial-scale atmospheric reorganizations. Open evergreen broadleaved forests persisted until the twentieth century, when they were partly substituted by widespread artificial pine plantations. Our results imply that highly flammable Erica vegetation, as reconstructed for the mid-Holocene, could re-emerge as a dominant vegetation type due to increasing drought and fire, as anticipated under global change conditions.     

Historic grazing in southern New England,USA, recorded by fungal spores in lake sediments

Decadal-scale analyses of fungal spores in a lake-sediment core from Ware Pond, located in the town of Marblehead in northeastern Massachusetts, test the potential of this approach for reconstructing past sheep and cattle grazing in southern New England, USA. The influx of spores of Sordaria and other coprophilous taxa increases at ad 1650, which corresponds with the beginning of European settlement, and subsequent peaks in these taxa at ad 1840 coincide with maximum abundances of weedy and agricultural taxa in the pollen record. Historical data from Marblehead and neighbouring towns indicate that maximum numbers of cattle and sheep occurred at this time. These findings suggest that fungal spores in New England lake sediments can be used to reconstruct changes in grazing pressure over time at the landscape scale.     

The Iron Age in the Mrągowo Lake District,Masuria, NE Poland: the Salęt settlement microregion as an example of long-lasting human impact on vegetation

Pollen, non-pollen palynomorphs, charcoal and geochemical analyses of sediments from Lake Sal?t (NE Poland) were used to reconstruct vegetation changes related to the activity of the West Balt tribes during the Iron Age, in the period between the second half of the 7th century bc and the beginning of the 10th century ad. We distinguished five phases of human impact on environment. Woodland clearing around the studied lake started at the end of the 7th century bc. The most characteristic feature of this area during the whole Iron Age was a very high representation of semi-natural Betula woodlands, which was probably linked to a shifting agriculture. This type of land use lasted for over 1,500 years, until the second half of the 9th century ad. The greatest reduction in Betula woodlands took place between cal. years 650 and 450 bc. Its regeneration took place after ca. ad 830 when human activity decreased.     

Olive cultivation in the heart of the Persian Achaemenid Empire: new insights into agricultural practices and environmental changes reflected in a late Holocene pollen record from Lake Parishan,SW Iran

Ancient Persia witnessed one of its most prosperous cultural and socio-economic periods between 550 bc and ad 651, with the successive domination of the Achaemenid, Seleucid, Parthian and Sassanian Empires. During this period agricultural activities increased on the Iranian plateau, as demonstrated by a remarkable arboricultural expansion. However, available data are not very informative about the spatial organization of agricultural practices. The possible links between climate conditions and agricultural activities during this millennium of continuous imperial domination are also unclear, due to the lack of parallel human-independent palaeoclimatic proxies. This study presents a new late Holocene pollen-based vegetation record from Lake Parishan, SW Iran. This record provides invaluable information regarding anthropogenic activities before, during and after the empires and sheds light on (i) spatial patterning in agricultural activities and (ii) possible climate impacts on agro-sylvo-pastoral practices during this period. Results of this study indicate that arboriculture was the most prominent form of agricultural activity in SW Iran especially during the Achaemenid, Seleucid and Parthian periods. Contrary to the information provided by some Greco-Roman written sources, the record from Lake Parishan shows that olive cultivation was practiced during Achaemenid and Seleucid times, when olive cultivation was significant, at least in this basin located close to the capital area of the Achaemenid Empire. In addition, pollen from aquatic vegetation suggests that the period of the latter centuries of the first millennium bc was characterized by a higher lake level, which might have favoured cultural and socio-economic prosperity.     

Glacial relics in the bryoflora of the highlands Českomoravská vrchovina (Bohemian-Moravian Highlands); Their habitat and cenotaxonomic value

The paper sums up the information which the author has so far collected about the habitats and phytocenotic conditions of the glacial relics ofScorpidium scorpioides (Hedw.) Limpr.,Calliergon trifarium (Web. etMohr.)Kindb.,Paludella squarrosa (Hedw.) Brid., andMeesia triquetra (Hook. etTayl.)Aongstr. in the Highlands ?eskomoravská vrchovina (Bohemian-Moravian Highlands) in Czechoslovakia. Simultaneously, it presents a survey of the localities in which the occurrence of these species has been ascertained up to now.     

Landscape use and fruit cultivation in Petra (Jordan) from Early Nabataean to Byzantine times (2nd century <Emphasis Type="SmallCaps">bc</Emphasis>–5th century <Emphasis Type="SmallCaps">ad</Emphasis>)

Archaeobotanical analyses of charred seeds, fruit and wood charcoal from the residential part of the ez-Zantur area at Petra, Jordan, provide new data on the agricultural economy and use of the landscape in this famous merchant Nabataean city from the middle of the 2nd century bc to the beginning of the 5th century ad. The study is based on analyses of 7,640 whole and fragmented seeds, pips and fruit stones and 624 charcoal fragments sampled from household deposits. The results show that the food supply was based on common Mediterranean cultivated taxa such as cereals (Hordeum vulgare, Triticum aestivum/durum), pulses (Lens culinaris) and fruit (Olea europaea, Ficus carica, Vitis vinifera), which were probably cultivated both in the city and its hinterland. The by-products from the processing of cereals and fruit trees played a significant role in fuel supply, supplementing woody wild plants obtained from rocky slopes and the desert valley. The variety of fuel resources shows a major capacity to manage complex supply networks and perhaps the rarity of natural woodland cover. The existence of orchards within the city centre and notably olive groves is indicated in the Early Nabataean period (mid 2nd century to mid 1st century bc) but they expanded during the Classical Nabataean period (mid 1st century bc to 1st century ad), probably reflecting specialised fruit growing. Unusual plant remains such as Prunus armeniaca (apricot), P. persica (peach) and Juglans regia (walnut) are considered to be social indicators of prosperity. These archaeobotanical results fit with others from this region and match with the urbanization and social dynamics of the city of Petra.     

Palaeocladocerans as indicators of environmental, cultural and archaeological developments in Eifel maar lakes region (West Germany) during the Lateglacial and Holocene periods

The use of subfossil cladocerans is rare for understanding environmental, cultural and archaeological developments of lakes in Europe. In 2007, we collected a 12-m long sediment core from Lake Schalkenmehrener Maar (SMM), Germany for the analyses of subfossil cladocerans. Dating of core was based on tephrochronology, radiocarbon and pollen stratigraphy. Pollen-based chronostratigraphy indicated a decline of species richness and abundance of chydorids during the Lateglacial (ca.14500?cal?yr?bp) with dominant cold preferring taxa Acroperus harpae Baird and Alona affinis Leydig. During the early B?lling, the abundance of cladocerans increased commensurate with growth of birch (Betula L.) and pine (Pinus L.) trees. Except a spike of Bosmina coregoni Baird during the Younger Dryas, cladoceran assemblages remained stable from the B?lling to the mid-Atlantic period. During the Neolithic (ca. 4300?bc), the abundance of B. coregoni increased sharply with reciprocal decrease in Daphnia. However, as soon as Daphnia was dominant (ca. 4250?bc), a reciprocal decline in abundance of B. coregoni occurred. The mid-Holocene change in cladoceran abundance coincided with the use of hardwood forest. This situation ended at ca. 4000?bc and remained unchanged throughout the Neolithic and Bronze Age (ca. 3000?C1200?bc). Low Daphnia abundance indicated reduced water quality in the Hunsr??ck-Eifel culture (ca. 800?bc). A spike of B. coregoni at ca. ad 150 indicates construction of the Roman Villa Rustica and extensive farming. However, reoccurrence of Daphnia at ca. ad 470 indicates the retreat of the Romans from the Eifel region. From the early Frankish rule (ca. ad 500) to the Medieval period (ca. ad 1500), species richness reduced but abundance of B. coregoni increased indicating a switch in lake ecosystem. The loss of species richness and the lack of precise evidence of the human activity in the region in the past have impeded the restoration of the ecosystem of the Lake SMM.     

Glacial relics in the bryoflora of the highlands Českomoravská vrchovina (Bohemian-Moravian Highlands); Their habitat and cenotaxonomic value

The paper sums up the information which the author has so far collected about the habitats and phytocenotic conditions of the glacial relics ofScorpidium scorpioides (Hedw.) Limpr.,Calliergon trifarium (Web. etMohr.) Kindb.,Paludella squarrosa (Hedw.) Bred., andMeesia triquetra (Hook. etTayl.) Aongstr. in the Highlands ?eskomoravská vrchovina (Bohemian-Moravian Highlands) in Czechoslovakia. Simultaneously, it presents a survey of the localities in which the occurrence of these species has been ascertained up to now.     

Investigations on in vitro anti-carcinogenic potential of <Emphasis Type="SmallCaps">l</Emphasis>-carnosine in liver cancer cells

This study was carried out to investigate the anti-carcinogenic effect of l-carnosine in human carcinoma cells (SNU-423). The SNU-423 cancer cells were cultured at a density of 2 × 10⁴ cells/well in Dulbecco modified Eagle medium. After 24 h of adherence, the cells were treated with l-carnosine (0.2 and 1 mg/mL) for 48 h. Then, cell viability was assessed by sulforhodamine assay, while mitochondrial dysfunction was measured by fluorescence microscopy using chromatin-specific dye Hoechst 33258. Intracellular levels of ROS were assayed by fluorescence spectroscopy with 2′,7′-dichlorofluorescein diacetate (DCFDA). l-Carnosine significantly inhibited the growth of the SNU-423 cells (p < 0.05). The inhibitory effect of l-carnosine was confirmed by results from mitochondrial fragmentation assay. The relative fluorescent unit was increased in a dose-dependent manner by l-carnosine, with values of 79.43, 186.87 and 400.89 for 0.6, 0.8 and 1 mg/mL of l-carnosine, respectively (p < 0.05). These results demonstrate that l-carnosine exerts anti-carcinogenic effects in human liver cancer cells.     

Identifying reference conditions for dimictic north German lowland lakes: implications from paleoecological studies for implementing the EU-Water Framework Directive

Using published paleolimnological results from 14 dimictic calcareous lakes, this study identifies total phosphorous (TP) reference values for the European lake type CB 1. The initial increase in settlement-associated pollen occurred in the catchments between ad ~1000 and ~1820. A departure from diatom-inferred TP reference conditions occurred during periods of increased human activities during Early to Late Medieval Times (ad ~1110–1325; four lakes), early Modern Times (ad ~1575–1600; two lakes), after the 30 years’ war (>ad 1650; two lakes) and during the Anthropocene (after ad ~1850, three lakes). Only one lake continuously has TP reference values until recent days, whilst TP reference values could not be detected in two cases. Thus, we refrain from setting a fixed point in time for defining reference conditions for lakes in the European Central Plains. This study also validates TP reference levels calculated based on common lake models for CB 1-lakes and assesses the range of TP reference levels using paleolimnological diatom studies. The highly variable diatom-inferred TP reference levels only partly support the modelled levels. Thus, we recommend using two subtypes (CB 1a and 1b), based on the watershed to volume ratio to better meet the requirements of lake type-specific reference levels.     

Stand-scale reconstruction of late Holocene forest succession on the Gdańsk Upland (N. Poland) based on integrated palynological and macrofossil data from paired sites

This study concerns the stand-scale palaeoecological reconstruction of the subsequent stages of late Holocene vegetation development on habitats recently covered by beech-dominated woodland in the southern Baltic region. The data, based on pollen, non-pollen palynomorphs, macrofossil and charcoal analyses from two close-lying sites, demonstrated that each of the subsequent late Holocene shifts in dominating forest communities took place because of human impact coupled with climatic events or episodic human-made disturbances. Shifts from the Tilia dominated forest to the Quercus-Corylus plant community at around 3300 bc was most probably driven by the coupled effect of climate change and human activity. Human impact was the primary driver of the final Corylus decline and concurrent major Carpinus expansion at c. 460 bc, and the Carpinus decline followed by Fagus expansion at c. ad 900. Carpinus had been lingering on the edge of a major expansion in the local forest for at least 2,500 years while Fagus had persisted in a small admixture for no fewer than 1,500 years before becoming important forest constituents. Our data illustrate the role of episodic disturbances as turning points that initiate long-term vegetation changes.     

Tracing a bog-iron bloomery furnace in an adjacent lake-sediment record in Ängersjö, central Sweden,using pollen and geochemical signals

Recent studies of bloomery sites in Sweden indicate the amount of iron produced with this early low-technology smelter was greater than previously thought, which implies greater economic importance. Little is known about the history of bloomery technology, not least the timeframe over which individual bloomeries were operated, as well as their impact on the landscape because of resource consumption and pollution. In this study we performed pollen and geochemical analyses of the lake-sediment record from Rörtjärnen, which is 120 m from the remains of a documented bloomery [one radiocarbon date: ad 1300–1435 (1 σ)], in Ängersjö, Hälsingland. A surface-soil transect shows a limited geochemical signal only within 20 m of the bloomery, and the sediment pollen record provides little direct evidence of an active bloomery and is consistent with other studied sites in the area linked to forest grazing or cultivation. Instead, we find major changes in sediment geochemistry during ad 800–1200, centered on a unique peak in Pb at ad 1030–1060. These changes include, e.g., Si (biogenic) and P, together with changes in pollen (e.g., Betula, Picea, Cyperaceae), which together indicate disturbance in the forest and especially the adjoining fen. We attribute these changes to a period of bloomery-related activities predating the radiocarbon date of the charcoal from the bloomery, and suggest that date represents a late phase for the site.     

Engineering an ATP-dependent <Emphasis Type="SmallCaps">d</Emphasis>-Ala:<Emphasis Type="SmallCaps">d</Emphasis>-Ala ligase for synthesizing amino acid amides from amino acids

We successfully engineered a new enzyme that catalyzes the formation of d-Ala amide (d-AlaNH₂) from d-Ala by modifying ATP-dependent d-Ala:d-Ala ligase (EC 6.3.2.4) from Thermus thermophilus, which catalyzes the formation of d-Ala-d-Ala from two molecules of d-Ala. The new enzyme was created by the replacement of the Ser293 residue with acidic amino acids, as it was speculated to bind to the second d-Ala of d-Ala-d-Ala. In addition, a replacement of the position with Glu performed better than that with Asp with regards to specificity for d-AlaNH₂ production. The S293E variant, which was selected as the best enzyme for d-AlaNH₂ production, exhibited an optimal activity at pH 9.0 and 40 °C for d-AlaNH₂ production. The apparent K _m values of this variant for d-Ala and NH₃ were 7.35 mM and 1.58 M, respectively. The S293E variant could catalyze the synthesis of 9.3 and 35.7 mM of d-AlaNH₂ from 10 and 50 mM d-Ala and 3 M NH₄Cl with conversion yields of 93 and 71.4 %, respectively. This is the first report showing the enzymatic formation of amino acid amides from amino acids.