The African cherry: A review of the botany, traditional uses, phytochemistry, and biological activities of Prunus africana (Hook.f.) Kalkman

ETHNOPHARMACOLOGICAL RELEVANCE

Prunus africana (Hook.f.) Kalkman (Rosaceae), commonly known as "Pygeum" or "African cherry", occurs in mainland montane forests scattered across sub-Saharan Africa, Madagascar, and some surrounding islands. Traditionally, decoctions of the stem-bark are taken orally for the treatment of a wide variety of conditions, such as benign prostatic hyperplasia (BPH), stomach ache, chest pain, malaria, heart conditions, and gonorrhoea, as well as urinary and kidney diseases. The timber is used to make axe handles and for other household needs. The dense wood is also sawn for timber.

AIM

The fragmented information available on the ethnobotany, phytochemistry, and biological activities of the medicinally important P. africana was collated, organised, and analysed in this review, to highlight knowledge voids that can be addressed through future research.

MATERIALS AND METHODS

A bibliometric analysis of research output on P. africana was conducted on literature retrieved, using the Scopus® database. The trend in the publications over time was assessed and a network analysis of collaborations between countries and authors was carried out. Furthermore, a detailed review of the literature over the period 1971 to 2021, acquired through Scopus, ScienceDirect, SciFinder, Pubmed, Scirp, DOAJ and Google Scholar, was conducted. All relevant abstracts, full-text articles and various book chapters on the botanical and ethnopharmacological aspects of P. africana, written in English and German, were consulted.

RESULTS

A total of 455 documents published from 1971 to 2021, were retrieved using the Scopus search. Analysis of the data showed that the majority of these documents were original research articles, followed by reviews and lastly a miscellaneous group comprising conference papers, book chapters, short surveys, editorials and letters. Data were analysed for annual output and areas of intense research focus, and countries with high research output, productive institutions and authors, and collaborative networks were identified. Prunus africana is reported to exhibit anti-inflammatory, analgesic, antimicrobial, anti-oxidant, antiviral, antimutagenic, anti-asthmatic, anti-androgenic, antiproliferative and apoptotic activities amongst others. Phytosterols and other secondary metabolites such as phenols, triterpenes, fatty acids, and linear alcohols have been the focus of phytochemical investigations. The biological activity has largely been ascribed to the phytosterols (mainly 3-β-sitosterol, 3-β-sitostenone, and 3-β-sitosterol-glucoside), which inhibit the production of prostaglandins in the prostate, thereby suppressing the inflammatory symptoms associated with BPH and chronic prostatitis.

CONCLUSIONS

Many of the ethnobotanical assertions for the biological activity of P. africana have been confirmed through in vitro and in vivo studies. However, a disparity exists between the biological activity of the whole extract and that of single compounds isolated from the extract, which were reported to be less effective. This finding suggests that a different approach to biological activity studies should be encouraged that takes all secondary metabolites present into consideration. A robust technique, such as multivariate biochemometric data analysis, which allows for a holistic intervention to study the biological activity of a species is suggested. Furthermore, there is a need to develop rapid and efficient quality control methods for both raw materials and products to replace the time-consuming and laborious methods currently in use.

The loneliness of the long-distance ethnobotanist: a constructive critique of methods used in an ethnoveterinary study in Mongolia

BACKGROUND

Fieldwork plays an important role in research projects across a variety of fields, especially in the multidisciplinary setting of natural and social science research. As is the nature of fieldwork, things do not always work out as planned, and yet this is not often written about. In response to the need for honest and transparent accounts of fieldwork, the purpose of this article is to review the methods used during fieldwork for the first author's dissertation research on ethnoveterinary knowledge.

METHODS

To critically review and reflect on the fieldwork methods used for an ethnoveterinary study in Mongolia, we compare the theory underpinning each method with the practical reality of implementing the method in the field. From this comparison, we draw out and discuss a number of key themes.

RESULTS

Eighteen methods and approaches used for the research project are reviewed and compared. From this, we distil and further discuss the following five overarching themes: reflections on specific data collection methods (free listing, semi-structured interviews with interpreters, voucher specimen collection); assumptions around involving local people; power dynamics; gender relations; and researcher well-being.

CONCLUSION

By juxtaposing the theory and practical reality of the methods used, we highlight many potential fieldwork challenges and, within this context, offer general pointers, especially for novice female researchers doing fieldwork in foreign countries. A critical review of this type, where the experience and use of various methods, techniques, and approaches are openly shared and evaluated, is a contribution to selecting, adapting, and fine-tuning the methods best suited to a particular research context.

From forest to pharmacy: Should we be depressed about a sustainable Griffonia simplicifolia (Fabaceae) seed supply chain?

ETHNOPHARMACOLOGICAL RELEVANCE

Griffonia simplicifolia D.C (Baill.) (Fabaceae) seeds are unusually high (6-20% wet weight) in 5-HTP (5-Hydroxytryptophan), a serotonin precursor widely used to treat depression. Consequently, this species is regarded as a herbal "Prozac®". Contemporary use as an anti-depressant contrasts with traditional uses for insecticides, arachnicides, fodder, dyes, mordants and chewing-sticks. G. simplicifolia seeds are wild-harvested for the export trade. Over the past 15 years, use of 5-HTP extracted from G. simplicifolia in cosmetics has added to global demand. Wild populations in West Africa are the sole commercial source of G. simplicifolia seed.

AIMS OF THE STUDY

Were to (i) assess the scale of the global trade in G. simplicifolia seeds and (ii) produce a synthesis of the challenges facing sustainable harvest of G. simplicifolia.

MATERIALS AND APPROACH

Firstly, we analysed global trade data for G. simplicifolia, taking into account historical trends over the past 40 years. Secondly, we reviewed published studies on the distribution, population biology and harvest impacts of wild G. simplicifolia populations.

RESULTS AND CONCLUSION

s: Wild G. simplicifolia populations have been the focus of commercial harvest of their pods (for seeds) for international trade from West Africa for almost 50 years. In the late 1980's, when Ghana exported 75-80 metric tonnes (MT) of G. simplicifolia seed to Europe, this species was already Ghana's main medicinal plant export. Currently, 5 West African countries export G. simplicifolia seeds (Cote d'Ivoire, Ghana, Liberia, Nigeria and Togo). Although in the 1980's, most seed exports were to Europe, today China is the main importer of G. simplicifolia seed. These seeds are value-added for production of 5-HTP extracts, and then re-exported, particularly to North America (c.48% of exports). The low habitat specificity and vigorous re-sprouting of G. simplicifolia after cutting, plus its occurrence in forest reserves and national parks confer some resilience on wild populations. Sustaining future supply chains faces six future challenges, however: (1) Rapid loss of forest habitats; (2) Declining populations of understorey birds and disruption of G. simplicifolia pollination in this bird pollinated species; (3) Negative effects of introduced invasive plant species (Broussonetia papyrifera, Chromolaena odorata) on G. simplicifolia regeneration; (4) Grazing by livestock and use of G. simplicifolia leaves as forage; (5) The long-term impact of industrial scale seed "predation": Over a 9-year period (2005-2013), G. simplicifolia exports from Ghana totalled at least 5550 metric tonnes (or between 9.1 billion to 13.5 billion seeds). This could affect the long-term population dynamics of this species, which produces a low number of seeds per pod (1-4 seeds) and has short distance (ballistic) seed dispersal; and (6) Destructive harvest methods, when plants are cut to harvest get the seed pods. Improved resource management, monitoring, quality control and careful pricing are important if supply chains from wild stocks are to be maintained. If wild populations decline, then 5-HTP biosynthesis may compete with low G. simplicifolia seed yields, leading to loss of income to West African harvesters and traders.

Running out of time to smell the roseroots: Reviewing threats and trade in wild Rhodiola rosea L

ETHNOPHARMACOLOGICAL RELEVANCE

Rhodiola rosea L. has a circumpolar distribution and is used in ethnomedicines of Arctic peoples, as well as in national systems of traditional medicine. Since the late 20th century, global demand for R. rosea has increased steadily, in part due to clinical research supporting new uses in modern phytotherapy. Global supply has been largely obtained from wild populations, which face threats from poorly regulated and destructive exploitation of the rootstocks on an industrial scale.

AIM OF THE STUDY

To evaluate (i) the conservation status, harvesting and trade levels of R. rosea, in order to determine whether international trade should be monitored, (ii) the current state of experimental and commercial farming and whether cultivation may play a role to take pressure off wild stocks, and (iii) evidence of substitution of other Rhodiola species for R. rosea as an indicator of overexploitation and rarity.

MATERIALS AND METHODS

We reviewed published studies on R. rosea biology and ecology, as well as information on impacts of wild harvest, on management measures at the national and regional levels, and on the current level of cultivation from across the geographic range of this species. Production and trade data were assessed and analysed from published reports and trade databases, consultations with R. rosea farmers, processors of extracts, and trade experts, but also from government and news reports of illegal harvesting and smuggling.

RESULTS AND CONCLUSIONS

Our assessment of historical and current data from multiple disciplines shows that future monitoring and protection of R. rosea populations is of time-sensitive importance to the fields of ethnobotany, ethnopharmacology, phytochemistry and phytomedicine. We found that the global demand for R. rosea ingredients and products has been increasing in the 21st century, while wild populations in the main commercial harvesting areas continue to decrease, with conservation issues and reduced supply in some cases. The level of illegal harvesting in protected areas and cross border smuggling is increasing annually coupled with increasing incidences of adulteration and substitution of R. rosea with other wild Rhodiola species, potentially negatively impacting the conservation status of their wild populations, but also an indicator of scarcity of the genuine article. The current data suggests that the historical primary reliance on sourcing from wild populations of R. rosea should transition towards increased sourcing of R. rosea from farms that are implementing conservation oriented sustainable agricultural methods, and that sustainable wild collection standards must be implemented for sourcing from wild populations.

Blue genome: chromosome-scale genome reveals the evolutionary and molecular basis of indigo biosynthesis in Strobilanthes cusia

Natural plant dyes have been developed and used across many traditional societies worldwide. The blue pigment indigo has seen widespread usage across South America, Egypt, Europe, India and China for thousands of years, mainly extracted from indigo-rich plants. The utilization and genetic engineering of indigo in industries and ethnobotanical studies on the effects of cultural selection on plant domestication are limited due to lack of relevant genetic and genomic information of dye plants. Strobilanthes cusia (Acanthaceae) is a typical indigo-rich plant important to diverse ethnic cultures in many regions of Asia. Here we present a chromosome-scale genome for S. cusia with a genome size of approximately 865 Mb. About 79% of the sequences were identified as repetitive sequences and 32 148 protein-coding genes were annotated. Metabolic analysis showed that the main indigoid pigments (indican, indigo and indirubin) were mainly synthesized in the leaves and stems of S. cusia. Transcriptomic analysis revealed that the expression level of genes encoding metabolic enzymes such as monooxygenase, uridine diphosphate-glycosyltransferase and β-glucosidase were significantly changed in leaves and stems compared with root tissues, implying their participation in indigo biosynthesis. We found that several gene families involved in indigo biosynthesis had undergone an expansion in number, with functional differentiation likely facilitating indigo biosynthesis in S. cusia. This study provides insight into the physiological and molecular bases of indigo biosynthesis, as well as providing genomic data that provide the basis for further study of S. cusia cultivation by Asia's traditional textile producers.

There "ain't no mountain high enough"?: The drivers, diversity and sustainability of China's Rhodiola trade

ETHNOPHARMACOLOGICAL RELEVANCE

Across Asia, Rhodiola species have been used in Bhutanese, Mongolian, Nepalese, Kazakh, Kyrgyz and Uzbek traditional medical systems. China is globally significant in terms of Rhodiola species diversity, with over 60% (55 species) of the world's 90 Rhodiola species, including 16 species found nowhere else in the world. Since the late 1980's there has been a shift from relatively low demand for infusions using chopped dried Rhodiola roots, to high 21st century demand for a wide variety of processed products. China's trade in Rhodiola products is now very diverse, with use in cosmetics and foods in addition to herbal products. Rhodiola crenulata (Hook.f. & Thomson) H.Ohba is the most widely traded species in China. In addition to R. crenulata and Rhodiola rosea L., 19 Rhodiola other species are used.

AIMS OF THE STUDY

These were to: (i) better understand why adulteration occurs in Rhodiola products; (ii) become more aware of what drives the growing market demand for Rhodiola products in China; (iii) find out whether increased demand is reflected in wholesale prices for Rhodiola raw materials traditional medicine markets; (iv) to examine Rhodiola supply chains and (v) given that wild populations are the primary supply source, to review the implications of growing demand for conservation and sustainable use.

MATERIALS AND METHODS

Firstly, we assessed growth in the diversity of Rhodiola products using three approaches: (i) by assessing patent applications for Rhodiola products in China (1990-2019); (ii) in 2018, through on-line searches of CFDA (China Food and Drug Administration) records for medicines and dietary supplements that had Rhodiola as an ingredient and (iii) by visiting retail stores in 2018 and 2019 to assess the diversity of commercial Rhodiola based products in trade. Secondly, we visited traditional medicine markets in Yunnan, Sichuan, and Qinghai provinces to investigate the trade in Rhodiola (folk taxonomy, trade names, prices, source areas, levels of processing and grading). Thirdly, we analysed the wholesale price data for Rhodiola raw materials in trade over a 16-year period (2002-2018). Fourthly, as most products come from wild collected Rhodiola species, we documented the extent of Rhodiola cultivation in China.

RESULTS

International exports of Rhodiola products from China, particularly extracts, is a major driver of commercial trade. One proxy indicator of Rhodiola product diversification in China has been the rapid rise in patent applications from single applications in 1990 and 1991, to a peak of 1017 patent applications in 2015. Wholesale price data from 2002 to 2018 shows a steady increase in wholesale prices. As the growing market for Rhodiola products in China is currently supplied entirely from wild collection, there are justifiable concerns about sustainability. Commercial cultivation needs to expand to meet future demand.

CONCLUSIONS

In contrast to Europe and North America, where R. rosea is the focal species in commerce, the trade in Rhodiola products in China is much more diverse. In the face of growing demand, both effective conservation of wild populations and cultivation are needed.

Scientists' Warning on Climate Change and Medicinal Plants

The recent publication of a World Scientists' Warning to Humanity highlighted the fact that climate change, absent strenuous mitigation or adaptation efforts, will have profound negative effects for humanity and other species, affecting numerous aspects of life. In this paper, we call attention to one of these aspects, the effects of climate change on medicinal plants. These plants provide many benefits for human health, particularly in communities where Western medicine is unavailable. As for other species, their populations may be threatened by changing temperature and precipitation regimes, disruption of commensal relationships, and increases in pests and pathogens, combined with anthropogenic habitat fragmentation that impedes migration. Additionally, medicinal species are often harvested unsustainably, and this combination of pressures may push many populations to extinction. A second issue is that some species may respond to increased environmental stresses not only with declines in biomass production but with changes in chemical content, potentially affecting quality or even safety of medicinal products. We therefore recommend actions including conservation and local cultivation of valued plants, sustainability training for harvesters and certification of commercial material, preservation of traditional knowledge, and programs to monitor raw material quality in addition to, of course, efforts to mitigate climate change.

Island blues: indigenous knowledge of indigo-yielding plant species used by Hainan Miao and Li dyers on Hainan Island, China

BACKGROUND

Historically, indigo-yielding plant species were important cash crops from Central Asia to the southern United States and Central America. Indigo-dyed textiles were widely traded along the legendary Silk Road that linked China to Europe. Today, due to the labor-intensive nature of indigo extraction at the household level, lifestyle changes and the widespread availability of commercially produced indigo paste, traditional indigo extraction methods have declined in villages. Yet Li textile weavers on Hainan Island are internationally recognized as producers of indigo-dyed textile using warp ikat techniques. In contrast, Hainan Miao weavers produce indigo-dyed textiles using batik (wax resist) techniques. The aim of this study was to document the indigenous knowledge on indigo-yielding plant species used by both Hainan Miao and Li people on Hainan Island, China.

METHOD

Ethnic uses were documented during three field surveys, through a questionnaire survey of 193 respondents, comprising 144 Hainan Miao and 49 Li traditional dyers. Mention index (QI), Availability index (AI), and Preference ranking (PR) of each indigo-yielding plant species were calculated to screen out plant resources with potential development value.

RESULTS

Five indigo-yielding plant species (from four plant families and four genera) were historically used by Hainan Miao and Li dyers. However, just four species are still in use. Strobilanthes cusia was the main indigo source for Hainan Miao dyers. Li dyers also commonly use Indigofera species (I. tinctoria and I. suffruticosa) for indigo extraction. Wrightia laevis is less commonly used as a contemporary indigo source. Indigo extraction by steeping in water to which lime is added to increase the pH is sharing by the five indigo-yielding plant species. Strobilanthes cusia had the highest QI, AI and PR values in Hainan Miao villages. Indigofera tinctoria had the highest QI and AI values, but Indigofera suffruticosa was preferred by Li dyers.

CONCLUSION

In the process of modernization and urbanization, some Hainan Miao and Li dyers retain the traditional indigo extraction methods. We found that Strobilanthes cusia and Indigofera tinctoria have the most potential for sustainable indigo production in the future. Furthermore, this study documents the details of extraction method from Wrightia laevis for the first time and the use of Ricinus communis seeds in that process. As one of the last places globally where Wrightia laevis is still used for indigo production, the may also be a nice market among textile collectors and museums that keeps the tradition of Wrightia laevis production and use for indigo extraction alive.

Identity blues: the ethnobotany of the indigo dyeing by Landian Yao (Iu Mien) in Yunnan, Southwest China

BACKGROUND

Indigo-dyed textiles have been central to the cultural identity of Landian Yao (literally "blue clothes Yao") people in Southwest China for centuries, driving a significant local market for naturally dyed indigo cloth. In the past two decades, local indigo production for traditional textiles has declined for several reasons: Firstly, the younger generation of Landian Yao has shifted to using western style jeans and T-shirts. Secondly, due to its labor-intensive nature. In contrast, at a global scale, including in China, there has been a revival of interest in natural indigo use. This is due to a growing awareness in the fashion industry about human and environmental health issues related to synthetic dye production. Ironically, this new awareness comes at a time when traditional knowledge of indigo dyeing is being lost in many places in China, with weaving and use of natural dyes now limited to some remote areas. In this study, we recorded indigo dyeing processes used by Landian Yao people and documented the plant species used for indigo dyeing.

METHODS

Field surveys were conducted to the study area from September 2015 to November 2016, supplemented by follow-up visits in July 2018 and November 2018. We interviewed 46 key informants between 36 and 82 years old who still continued traditional indigo dyeing practices. Most were elderly people. Semi-structured interviews were used. During the field study, we kept a detailed account of the methods used by Landian Yao dyers. The data were then analyzed by using utilization frequency to determine the best traditional recipe of indigo dye extraction. All the specimens of documented species were collected and deposited at the herbarium of Kunming Institute of Botany.

RESULTS

Our results showed that indigo dyeing was divided into two main steps: (1) indigo pigment extraction and (2) dyeing cloth. The general procedures of indigo dye extraction included building or buying a dye vat, fermentation, removal of the leaves of indigo producing plant species, addition of lime, oxygenation, followed by collection, and the storage of the indigo paste. The procedures of dyeing cloth included preparing the dye solutions, dyeing cloth, washing, and air drying. It is notable that Landian Yao dyers formerly only performed the dyeing process on the goat days in the lunar calendar from June to October. After comparing the range of local indigo extraction methods, our results showed that the following was best of these traditional recipes: a indigo-yielding plant material to tap water ratio of 30 kg: 200 l, lime 3 kg, a fermentation time of 2-3 d, aeration by agitation for up to 60 min, and a precipitation time of 2-3 h. Our results show that 17 plant species in 11 families were recorded in the indigo dyeing process. With the exception of the indigo sources, only Dioscorea cirrhosa Lour. and Artemisia argyi H.Lév. & Vaniot were previously recorded in dyeing processes. Other species given in this paper are recorded for the first time in terms of their use in the indigo dyeing process. In the study area, Landian Yao men were in charge of indigo dye extraction, and the women were responsible for dyeing cloth.

CONCLUSIONS

The Landian Yao has completely mastered the traditional indigo dyeing craft and are one of the well-deserved identity blues. Indigo production from plants using traditional methods is a slow process compared to synthetic dyes and is not suitable for modern and rapid industrial production. Therefore, our study records the detailed information of traditional indigo dyeing to protect and inherit it. Strobilanthes cusia (Nees) Kuntze is the main indigo source in Landian Yao that is widely used in the world and can be commercially exploited as an indigo plant. For commercial and environment benefits, we suggest that producing natural indigo for the commercial market is a good choice.

Linking resource supplies and price drivers: Lessons from Traditional Chinese Medicine (TCM) price volatility and change, 2002-2017

ETHNOPHARMACOLOGICAL RELEVANCE

Worldwide, one of the drivers of substitution and adulteration is the cost of the natural resources (plants, animals, fungi) that are ingredients of traditional medicines. Relatively few studies have been done that link prices of traditional medicine ingredients to what drives changes in price, yet this is an important topic. Theoretically, prices have been widely considered as an economic indicator of resource scarcity. Rare, slow growing medicinal plants sell for high prices and common, less popular species for low prices. Price levels also influence the viability of farming vs. wild harvest (and incentives to overharvest high value species when tenure is weak). Prices can also influence the harvesting or buying behaviour of harvesters, traders or manufacturers. When prices are high, then there is a greater incentive to use cheaper substitute species or adulterants. As previous studies on herbal medicine ingredients have shown, adulteration applies in a wide variety of cases, including to some Traditional Chinese Medicine (TCM) species.

AIM OF THE STUDY

The aim of this study was to gain a better understanding of which factors influenced changes in the market prices of document prices for four popular, but very different traditional Chinese medicine (TCM) species (2002 - 2017).

MATERIALS AND METHODS

Fluctuations in market prices were followed over a 15-year period (2002-2017) for four very different TCM ingredients: two plant species (one wild harvested for fruits (Schisandra sphenanthera Rehder & E.H. Wilson) the other in a transition from wild harvest to cultivation (Paris polyphylla Smith), an animal species (the Tokay gecko (Gekko gecko L.)) and the entomophagous "caterpillar fungus" (Ophiocordyceps sinensis (Berk). G.H. Sung, J.M. Sung, Hywel-Jones & Spatafora).

RESULTS

High prices of medicinal plants are widely considered to reflect resource scarcity. Real-time market prices for three of the four very different TCM species we studied all showed major price fluctuations. The exception was P. polyphylla, whose wild populations are widely known to be increasingly scarce, where there was a steady increase in price, with few fluctuations in the upward price trend. The three other species showed significant price fluctuations. These were driven by multiple factors. Ecological and biogeographic factors that influence abundance or scarcity of supply certainly played a role. But other factors were also influential. These included both national and global economic factors (the influence of the Global Financial Crisis (GFC)), national policy changes that in turn influenced businessmen giving expensive gifts (that included O. sinensis)), climate change (influencing fruiting success of S. sphenanthera), price speculation by traders and lack of information (e.g: reduction in G. gecko prices due to traders incorrectly believing that domestication would increase supplies).

CONCLUSIONS

Price fluctuations in the four TCM species we examined are influenced by many factors and not just resource scarcity. And the situation is more complex than the trajectory based on Homma's (1992) model, where he predicted that higher prices would result in a shift to cultivation, thus replacing wild harvest. In case of both O. sinensis and P. polyphylla, Homma (1992, 1996) was right in terms of scarcity and high prices stimulating a major investment in cultivation (P. polyphylla) and artificial production (O. sinensis). But in both cases, intensive production through cultivation or artificial propagation do not yet occur on a large enough scale to reduce harvest of wild stocks. Substitution and adulteration occur with all four species. Improving information to medicinal plant traders on the supply status of TCM stocks, whether from wild harvest or from cultivation could benefit product quality, cultivation initiatives and conservation efforts.

Introduction to the special issue: Saving plants, saving lives: Trade, sustainable harvest and conservation of traditional medicinals in Asia

This "geographic and thematic" issue of the Journal of Ethnopharmacology focuses on the traditional medicines in trade in Asia on the 30th anniversary of the 1988 Chiang-Mai Declaration, an output of an historic meeting organized by WHO, IUCN and WWF. The emphasis on the Asian countries that represent the highest volume and value of medicinal plants trade in the world is deliberate. Not only because of the scale and speed of changes in traditional medicines trade in Asia, but also to highlight the conservation and sustainable use issues being faced today. In 1988, few studies had been done on the informal sector trade or on medicinal plant value-chains and even fewer studies on cross-border trade in medicinal plants or fungi. At that time, e-commerce in Traditional and Complementary Medicine (T&CM), so common today, did not even exist. And no comparitive, repeat studies of traditional medicines markets had been done at all. Thirty years later, this special issue illustrates how the traditional medicines trade has grown and changed. Links between medicinal plant conservation, scarcity and price on one hand and quality, safety and adulteration on the other are better understood. E-commerce in T&CM has grown exponentially, due to 51% of the world's population having internet access by 2017. Yet despite global policy goals for conservation and sustainable use, the challenges facing medicinal plants conservation are greater than ever before. Consequently, the need for co-operation between the health-care and conservation sectors recognised in 1988 is even greater today. And this is recognised in WHO's 2014-2023 strategy for traditional medicines, which identifies the need to raise awareness about issues of biodiversity and conservation as an important strategic action (WHO, 2013). This Special Issue is a small contribution towards that goal.

Impact of hydrologic boundaries on microbial planktonic and biofilm communities in shallow terrestrial subsurface environments

Subsurface environments contain a large proportion of planetary microbial biomass and harbor diverse communities responsible for mediating biogeochemical cycles important to groundwater used by human society for consumption, irrigation, agriculture and industry. Within the saturated zone, capillary fringe and vadose zones, microorganisms can reside in two distinct phases (planktonic or biofilm), and significant differences in community composition, structure and activity between free-living and attached communities are commonly accepted. However, largely due to sampling constraints and the challenges of working with solid substrata, the contribution of each phase to subsurface processes is largely unresolved. Here, we synthesize current information on the diversity and activity of shallow freshwater subsurface habitats, discuss the challenges associated with sampling planktonic and biofilm communities across spatial, temporal and geological gradients, and discuss how biofilms may be constrained within shallow terrestrial subsurface aquifers. We suggest that merging traditional activity measurements and sequencing/-omics technologies with hydrological parameters important to sediment biofilm assembly and stability will help delineate key system parameters. Ultimately, integration will enhance our understanding of shallow subsurface ecophysiology in terms of bulk-flow through porous media and distinguish the respective activities of sessile microbial communities from more transient planktonic communities to ecosystem service and maintenance.

Twists, turns and trade: A new look at the Indian Screw tree (Helicteres isora)

ETHNOPHARMACOLOGICAL RELEVANCE

This is the first study of global trade in fruits of the widely used traditional medicine, Helicteres isora L. It is used in Ayurvedic, Siddha, Unani medical systems and/or local folk traditional medicines in Bangladesh, India and Pakistan. The roots are used in Traditional Chinese Medicines in China and the fruits in jamu products in Indonesia, Malaysia and Thailand. In addition, H. isora fruits are also used in "traditional" medical systems far beyond the natural distribution of this species, for example in Zulu herbal medicine (South Africa) and Kurdish herbal medicines (Iraq).

AIMS OF THE STUDY

This study had three aims: (i) to assess the global trade in H. isora fruits; (ii) to study the H. isora trade from West Timor to Java in terms of actors and prices along the value chain and (iii) to get a better understanding of the potential of this species to improve household income in eastern Indonesia.

MATERIALS AND METHODS

This study uses historical records, a contemporary analysis of global trade data (2014-2016) and field assessments of value chains and the biological factors influencing H. isora fruit production.

RESULTS

Globally, the major exporter of H. isora fruits is India, which exports H. isora fruits to 19 countries, far beyond the natural geographical distribution of this species. Over a 36-month period (January 2014-December 2016), India exported 392 t of H. isora fruits, with a Free-On-Board (FOB) value of Indian rupiah (INR) 18,337,000 (US$ 274,055). This represents an average annual export quantity of about 130,526 kg/year. Over this three year period, most of these exports (85.5%) were to Indonesia (346.58 t), followed by Thailand (6.85%). Indian H. isora exports are also used in many other medical systems, including Kurdish and Zulu "traditional" medicines in Iraq and South Africa. Formation of an Indian diaspora in Bahrain, Mauritius, South Africa, Tanzania and Trinidad and Tobago over the past 130 years is one of the drivers of H. isora fruit trade outside the natural geographic distribution of the species. In Indonesia, demand for H. isora fruits is supplemented by an intra-island trade in Java and an inter-island trade from East Nusa Tenggara. West Timor, for example, exports around 31-37 t of air-dried H. isora fruits per year to Java. At the farm gate, local harvesters in West Timor get 4000 IDR (c. 0.3 US$) per kg, with businesses in Java paying 25,000 IDR (c.US$2) per kg for H. isora fruits. This is similar to the price paid for H. isora fruits imported from India to Java.

CONCLUSIONS

India is the major exporter of whole dried H. isora fruits, including to countries where this species has never been in traditional use. In Indonesia, H. isora fruit extracts are used in the cosmetic industry as well as in jamu herbal medicines, including "Tolak Angin", the country's most popular commercial "jamu" preparation. Indonesia also is the major importer of H. isora fruits from India. In eastern Indonesia, improved income to local villagers from the H. isora fruit trade could come from improved H. isora fruit quality due to better drying techniques. This would also reduce health risks along the supply chain from to mycotoxins that have been recorded on poorly dried H. isora fruits. There also is an opportunity for cultivation of H. isora in small-holder teak plantations in Indonesia, with harvest of H. isora fruits as well as the medicinal bark.

Production from both wild harvest and cultivation: The cross-border Swertia chirayita (Gentianaceae) trade

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia chirayita is the most widely traded species in a genus of 150 species, many of which are used in traditional medicine. S. chirayita is used mainly in Ayurvedic and Tibetan systems of medicine and the homoeopathic system of medicine as well as in regional folk medicine. Primarily wild collected, with some cultivation. S. chirayita is traded as a medicinal substance and exported in the forms of dried whole plant or extract of whole plant individually and/or as active ingredients of Ayurvedic medicines. S. chirayita export valuations continue to make S. chirayita one of Nepal's highest foreign exchange earning medicinal plant species.

AIMS OF THE REVIEW

The aims of this review were first, to assess the scale of the global trade in S. chirayita, second, to review evidence from plant population biology and from studies on the impacts of wild harvest on S. chirayita populations and cultivation as an alternative source of supply.

METHODS

The taxonomy and trade names for S. chirayita were reviewed, followed by a synthesis of published information on Swertia population biology and studies on impacts of wild S. chirayita harvest from across the geographic range of this species. Data on the prices paid for S. chirayita were then compiled for the period 2001-2017, followed by an analysis of global trade data for S. chirayita.

RESULTS AND CONCLUSIONS

Based on India import data and assuming an estimate in an earlier study that 60% of Nepal's S. chirayita production goes to India and 35% to Tibet, then Nepal's 2013 annual production was about 711 metric tonnes (MT) of which about 675.6 MT would be exported (India + Tibet). Nepal's 2014 annual production would be an estimated 503.25 MT of which about 478 MT would be exported. Declines in S. chirayita populations have been widely noted across its range. In India, since 2004, a ban was placed on the export of wild harvested S. chirayita by the Government of India, where the Director General of Foreign Trade prohibited export of S. chirayita plants, plant portions and their derivatives and extracts obtained from the wild with the exception of 'formulations'. Cultivation of S. chirayita to meet commercial demand has been an important part of a solution to over-exploitation of wild stocks in eastern Nepal for 25 years, producing significant quantities that enter the export trade to India and Tibet. In Sankhuwasabha district, for example, 53.1 MT of S. chirayita were produced in 2013/014, just over half of which (27 MT) were exported to India, with the remainder exported to Tibet. Based on value-chain analysis and cost-benefit assessments, S. chirayita cultivation has been shown to be profitable in Nepal. However, since the first cost-benefit assessment was done (2013), prices dropped from NRs750/kg in April 2013 to a low of 250 NRs/kg in December 2017). Taking inflation into account further highlights the steep decline in the profitability for local farmers, who have limited options for value-adding. Consequently, farmers prefer to grow more profitable alternative crops, such as Nepal cardamom (Amomum subulatum Roxb.).

Sustainable harvest, people and pandas: Assessing a decade of managed wild harvest and trade in Schisandra sphenanthera

ETHNOPHARMACOLOGICAL RELEVANCE

Endemic to China, the distribution of Schisandra sphenanthera Rehder & E.H. Wilson includes giant panda (Ailuropoda melanoleuca David, 1869) habitats in forests of the Minshan and Qinling Mountains, both inside and outside conservation areas. The fruit is used in indigenous medicines of the Qiang, Tibetan and Yi ethnic minorities of Sichuan. Also used in traditional Chinese medicine (TCM), indications for use are prescribed in the Chinese Pharmacopoeia. For continued access and medical use, survival of healthy populations depends on forests. Biodiversity conservation programmes implemented in forests within the panda landscapes that also benefit rural and indigenous communities, link future access to wild medicinal plants with survival of the panda and resilient rural economies.

AIMS OF THE STUDY

This study aimed at assessing the project activities, institutional-level outcomes and achievements, 10 years on, of the 5-year (2007-2011) UNDP- and WWF- supported EU-China Biodiversity Programme for sustainable, "panda-friendly" schisandra.

MATERIALS AND METHODS

Our study combined analysis of quantitative data such as purchase records coupled with qualitative data obtained from field work, project documents, site-visit reports, certification documents and published articles about the project.

RESULTS

At start of project, interested companies were identified to support economic viability of the sustainable wild harvesting and a "panda friendly" pro-conservation model that provided an incentive to maintain habitat outside formal protected areas. Criteria of relevant sustainability standards, the Organic Wild-crop Harvesting Practice Standard and FairWild Standard, were applied while a new standard was drafted, the Giant Panda Friendly Products Standard. The initial pilot project involving 1 village determined feasibility leading to formation of the Pingwu Shuijing TCM Cooperative which, by 2016, scaled out to membership of 22 villages. From the cooperative's first commercial sale of S. sphenanthera Rehder & E.H.Wilson fruits of 0.5 MT in 2009, annual quantities steadily increased up to 30 MT sold in 2017. The cooperative achieved organic certification in 2012. In 2016, governmental authorisation for the certification of Chinese operations implementing the FairWild Standard was granted. In 2017, the Giant Panda Friendly Products Standard became an official Chinese standard with the cooperative becoming the first panda-friendly certified operation in 2018.

CONCLUSIONS

A decade after the project first started, there is strong evidence for the pro-conservation micro- and small enterprise model. For example, through the establishment of a TCM cooperative with members in 22 villages engaged in sustainable resource management, harvesting and equitable trade of TCM ingredients with organic and panda-friendly branding. The project benefited from multi-disciplinary collaboration of experts in ethnoecology, TCM, panda biology and habitat, nature conservation, sustainability standards and international trade. Inviting interested companies at the start enabled a transition from a funded-project to annual contracts for sustainably harvested TCM herbal drugs. At end of project (2011), the companies and NGOs remained engaged and motivating for completion of activities started during the project. Major eventual outcomes rooted in the initial project included Chinese government authorisation of the FairWild Standard (2016) and Giant Panda Friendly Products Standard (2017).

High altitude species, high profits: Can the trade in wild harvested Fritillaria cirrhosa (Liliaceae) be sustained?

ETHNOPHARMACOLOGICAL RELEVANCE

Fritillaria cirrhosa D. Don bulbs contain alkaloids and are one of the most intensively exploited alpine Himalayan medicinal species. In terms of proprietary medicines, our study shows that 210 F. cirrhosa products are offered by 46 suppliers, most of which (44) are situated in China and two in Nepal. A widespread commercial use is as one of the main ingredients in cough syrups. A well known example is "Nin Jiom Pei Pa Koa Herbal Cough & Throat Syrup", which typically contains more F. cirrhosa than any other herbal ingredient in the formulation. The biggest market for F. cirrhosa bulbs is China, where demand exceeds supply of this wild harvested species for use in traditional Chinese medicine (TCM). Cross-border trade from Nepal to China occurs in significant quantities. Bhutan also imports F. cirrhosa bulbs from Nepal. In addition, F. cirrhosa is registered as an active ingredient in traditional herbal medicinal preparations in Australia, Canada, Hong Kong SAR, Malaysia, Republic of Korea, Singapore and Taiwan. There is also an export trade in F. cirrhosa to Europe. Assessing how much F. cirrhosa is traded is complex, however, due to a "look-alike" challenge, as nine Chinese Fritillaria species are traded in Europe (Fritillaria cirrhosa, F. delavayi, F. hupehensis, F. pallidiflora, F. przewalskii, F. thunbergii, F. unibracteata, F. ussuriensis and F. walujewii).

AIMS OF THE STUDY

The aims of this review were to assess the scale of the global trade in F. cirrhosa, and to synthesise studies of the impacts of wild harvest on F. cirrhosa populations and on the extent of emerging cultivation initiatives as an alternative to wild harvest.

METHODS

Firstly, we reviewed published information on studies on impacts of wild F. cirrhosa harvest from across the geographic range of this species. Secondly, global trade data for F. cirrhosa were analysed.

RESULTS

The principal demand for F. cirrhosa bulbs is in China, where hundreds of different companies produce Fritillaria preparations. Trade data also show that in 2013, China exported over 44 tonnes of F. cirrhosa bulbs to Taiwan and 26.7 tonnes to the Republic of Korea. Extensive commercial use and limited wild stocks result in a high price (2000 - 3800 CNY per kg (around US$ 303 -560 per kg in 2017)) for F. cirrhosa bulbs. Prices of cultivated Fritillaria bulbs are much lower (600-680 CNY per kg in 2017) than wild harvested bulbs. But due to very specific growth requirements of F. cirrhosa, cultivation is not yet able to meet total demand. The consequence is continued exploitation of wild stocks. At the same time, however, an increasing proportion of the demand is met by cultivation of alternative Fritillaria species that are easier to grow than F. cirrhosa. The air-dry mass of F. cirrhosa bulbs varies between 0.0917 and 0.1116 g per bulb. This represents 8960 - 10,900 bulbs/kg or 8.9 - 10.9 million bulbs per tonne. Current demand therefore represents billions of bulbs per year.

CONCLUSIONS

Demand for F. cirrhosa bulbs, particularly from China, makes this species one of the most intensively harvested alpine Himalayan medicinal bulbs. Although F. cirrhosa is listed as a Class III protected species in China, billions of these tiny, wild harvested bulbs are sold per year. Due to demand exceeding supply, the price of F. cirrhosa bulbs has increased dramatically. Between 2002 and 2017, for example, the price of wild harvested F. cirrhosa bulbs increased over nine-fold, from the equivalent of US$60 in 2002 to US$560 per kg in 2017. To date, cultivation has been unable to meet the entire market demand for F. cirrhosa bulbs, although other Fritillaria species are successfully cultivated on a larger scale.

Rising trade, declining stocks: The global gugul (Commiphora wightii) trade

ETHNOPHARMACOLOGICAL RELEVANCE

Commiphora wightii is exploited in India and Pakistan for an oleo-resin (gum guggul) traditionally used in Ayurvedic, Siddha and Unani medical systems. Processed C. wightii oleo-resin products are exported from India to 42 countries, including re-export to Pakistan, for anti-inflammatory use and as an anti-inflammatory and an anti-obesity treatment considered to lower cholesterol and lipid levels. The C. wightii export trade has particular relevance to the European Union because Belgium, France, Germany, Hungary, Italy, the Netherlands, and United Kingdom are importing countries. Demand and prices for C. wightii oleo-resin are increasing and wild stocks of C. wightii are in decline. The overexploitation of C. wightii after tapping for its commercially valuable oleo-resin is not a new problem, however, but one that has existed for over 50 years. Lopping and chopping trees to extract C. wightii oleo-resin has had a devastating impact on C. wightii populations since the 1960's.

AIM OF THE STUDY

The aim of this study was to review the sustainability of the global trade in C. wightii oleo-resin. This included reviewing studies on resin tapping methods and the impacts of wild harvest on C. wightii populations in India and Pakistan.

MATERIALS AND METHODS

Firstly, we reviewed studies on impacts of C. wightii oleo-resin harvest and on the policy responses taken in relation to harvest and trade in C. wightii oleo-resin. Secondly, we reviewed studies on C. wightii cultivation. Thirdly, global trade data for C. wightii were analyzed.

RESULTS AND CONCLUSIONS

Destructive harvest to obtain the gum is the major threat facing this species. C. wightii populations are also fragmented by habitat loss through clearing for farming. Cutting and lopping in order to extract the medicinal gum are a major threat to C. wightii populations, as is poor recruitment due to grazing by livestock. As a result of over-exploitation, C. wightii oleo-resin production has declined in India. In Gujarat, a key production area, the decline over a 50-year period has been from 30 t in 1963, to 2.42 t in 1999 to 1.6 t in 2013. Consequently, large quantities of C. wightii oleo-resin (around 505 t/year) are imported into India from Pakistan. An estimated 193 t/year of crude gum equivalent is exported from India in the form of processed products. With remaining populations in decline due to commercial exploitation for international trade, a range of policy options (such as CITES Appendix II listing) and practical conservation actions (such as cultivation) need to be considered.

Paris in the spring: A review of the trade, conservation and opportunities in the shift from wild harvest to cultivation of Paris polyphylla (Trilliaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

P. polyphylla Smith is used in traditional medicine in China, India and Nepal and is likely to be similarly used through most of its geographic range. China is at the centre of demand for P. polyphylla where it is used as an ingredient in several very successful Chinese medicinal herbal formulations. The Chinese e-commerce platform 'alibaba.com', for example, lists 97 P. polyphylla items offered by 46 Asian suppliers, of which 21 are situated in the Chinese mainland, 12 in Nepal, 7 in India, 2 in Pakistan, and 1 each in Bhutan, Hong Kong, Thailand, and Vietnam. Products offered include the crude drug (dried whole or cut rhizomes), extracts and formulations containing this herbal drug.

AIMS OF THE REVIEW

The aims of this review were to assess the scale of the P. polyphylla trade, reviewing evidence on the impacts of wild harvest on P. polyphylla populations and on the role of cultivation as an alternative to wild harvest.

MATERIALS AND METHODS

Firstly, we reviewed published information on Paris population biology and studies on impacts of wild P. polyphylla harvest from across the geographic range of this species. Secondly, global trade data for P. polyphylla were analysed. Thirdly, we reviewed published information on P. polyphylla cultivation and made field visits to P. polyphylla cultivation areas in Yunnan and Sichuan.

RESULTS

Since the 1980s, there has been a 400-fold increase in the market price paid in China for P. polyphylla rhizomes, from 2.7 Chinese Yuan (CNY) per kg in the 1980s to market prices up to 1100 CNY per kg in 2017. Cross-border trade in dried P. polyphylla rhizomes occurs at three different scales. Firstly, an internal, national trade of P. polyphylla rhizomes within countries (such as India, Nepal and China). Secondly, trade in P. polyphylla rhizomes from Nepal (and possibly from Bhutan) to the two range states that have the largest traditional medicine trade in the world: China and India. Thirdly, trade in processed herbal products. In China, for example, P. polyphylla is widely used as an ingredient in several very successful herbal products, including a famous first aid treatment to stop bleeding. Some of these products are exported globally, in addition to entering into regional trade. Trade data in our review shows that c. 800-1050 t of P. polyphylla rhizomes are sold annually, significantly more than recorded in earlier studies. China is the only country where P. polyphylla is cultivated on a significant scale, although small-scale cultivation is taking place in India and Nepal.

CONCLUSIONS

Based on the criteria for the inclusion of species in CITES Appendix II (Art. IV 2(a)), there is compelling evidence for adding Paris polyphylla. At the same time, cultivation of P. polyphylla outside of high conservation value habitats needs to be encouraged and supported. One way of doing this may be to develop separate, traceable supply chains for cultivated supplies in order to distinguish them from wild harvested stocks.

A billion cups: The diversity, traditional uses, safety issues and potential of Chinese herbal teas

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal teas have long been consumed by Chinese people for preventive and/or therapeutic healthcare. Although herbal teas are widely consumed by many cultural groups in different regions of China, no thorough review has been undertaken to assess the diversity of the country's herbal tea usage. This literature review, complemented by a quantitative survey in an important tea market in Kunming, begins to fill this knowledge gap.

AIMS OF THE STUDY

The study aims to summarize the current knowledge of plant species used as herbal teas by different cultural groups in different regions of China, with a focus on the teas' perceived traditional healthcare functions, related phytochemical/pharmaceutical research, and safety issues.

MATERIALS AND METHODS

The study involved a comprehensive literature review and a market survey. The literature review was based on published ethnobotanical studies of herbal teas in China. We searched the Web of Science™, ELSEVIER, the China National Knowledge Infrastructure (CNKI) and the China Science and Technology Journal Database to locate relevant studies (including journal articles, Masters/PhD dissertations and books) that were published before March 2017. A species list was compiled based on the review and supplemented with information retrieved from the Scifinder database (https://scifinder.cas.org) and the Chinese Pharmacopoeia (2010). A Use Value Index was employed for ranking the most cited species. Based on the 29 most cited species, we discussed the current research status in relation to healthcare benefits and safety concerns of herbal teas in China. To better understand the current status of the herbal tea market in China, we also surveyed 136 tea vendors at the Xiongda Tea Market in Kunming. Information gathered from the survey included the species sold, the sale prices and the form of the herbal tea product.

RESULTS

The literature identified 759 plant species used as herbal tea in China and the market survey identified an additional 23 species. Most of the species used were from the Leguminosae, Compositae and Lamiaceae families. Twenty two provinces and fourteen ethnic minority groups have records on the consumption of herbal teas. Southern China uses up to 82% of the total species, and 211 out of 759 species are used by minority groups. Thirty categories of traditional healthcare functions are linked with herbal teas, with clearing away heat, relieving toxicity and suppressing cough being the most important functions. There is phytochemical/pharmaceutical evidence to support the claimed healthcare benefits of some Chinese herbal teas. Although Chinese herbal teas are generally safe to consume, overdoses of some herbal teas and some unapproved mixtures of species may cause health risks. Based on our market survey, the prices of most herbal teas range between 100 and 200 RMB (US$15-30) per kg.

CONCLUSIONS

A rich array of herbal tea species with various traditional healthcare functions have long been used in China, and as such there is a huge market potential for Chinese herbal teas. More pharmaceutical/phytochemical research is needed to assess a wide range of perceived healthcare benefits of Chinese herbal teas. Our research highlights the need to study herbal teas through an ethnopharmacological perspective and by employing a holistic approach, which requires greater consideration of traditional knowledge in the pharmacological research design. Product safety and sustainability issues should also be considered, so the traditional applications of herbal teas can be transformed to efficient health boosting functional products.

Risks to birds traded for African traditional medicine: a quantitative assessment

Few regional or continent-wide assessments of bird use for traditional medicine have been attempted anywhere in the world. Africa has the highest known diversity of bird species used for this purpose. This study assesses the vulnerability of 354 bird species used for traditional medicine in 25 African countries, from 205 genera, 70 families, and 25 orders. The orders most represented were Passeriformes (107 species), Falconiformes (45 species), and Coraciiformes (24 species), and the families Accipitridae (37 species), Ardeidae (15 species), and Bucerotidae (12 species). The Barn owl (Tyto alba) was the most widely sold species (seven countries). The similarity of avifaunal orders traded is high (analogous to “morphospecies”, and using Sørensen's index), which suggests opportunities for a common understanding of cultural factors driving demand. The highest similarity was between bird orders sold in markets of Benin vs. Burkina Faso (90%), but even bird orders sold in two geographically separated countries (Benin vs. South Africa and Nigeria vs. South Africa) were 87% and 81% similar, respectively. Rabinowitz's “7 forms of rarity” model, used to group species according to commonness or rarity, indicated that 24% of traded bird species are very common, locally abundant in several habitats, and occur over a large geographical area, but 10% are rare, occur in low numbers in specific habitats, and over a small geographical area. The order with the highest proportion of rare species was the Musophagiformes. An analysis of species mass (as a proxy for size) indicated that large and/or conspicuous species tend to be targeted by harvesters for the traditional medicine trade. Furthermore, based on cluster analyses for species groups of similar risk, vultures, hornbills, and other large avifauna, such as bustards, are most threatened by selective harvesting and should be prioritised for conservation action.

Floating treatment wetlands for domestic wastewater treatment

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ∼50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment.

Effects of Motility and Adsorption Rate Coefficient on Transport of Bacteria through Saturated Porous Media

Three strains of Pseudomonas fluorescens with different motility rates and adsorption rate coefficients were injected into porous-medium reactors packed with l-mm-diameter glass spheres. Cell breakthrough, time to peak concentration, tailing, and cell recovery were measured at three interstitial pore velocities (higher than, lower than, and much lower than the maximal bacterial motility rate). All experiments were done with distilled water to reduce the effects of growth and chemotaxis. Contrary to expectations, motility did not result in either early breakthrough or early time to peak concentration at flow velocities below the motility rate. Bacterial size exclusion effects were shown to affect breakthrough curve shape at the very low flow velocity, but no such effect was seen at the higher flow velocity. The tendency of bacteria to adsorb to porous-medium surfaces, as measured by adsorption rate coefficients, profoundly influenced transport characteristics. Cell recoveries were shown to be correlated with the ratio of advective to adsorptive transport in the reactors. Adsorption rate coefficients were found to be better predictors of microbial transport phenomena than individual characteristics, such as size, motility, or porous-medium hydrodynamics.

Interaction of Klebsiella oxytoca and Burkholderia cepacia in dual-species batch cultures and biofilms as a function of growth rate and substrate concentration

Dual-species microbial interactions have been extensively reported for batch and continuous culture environments. However, little research has been performed on dual-species interaction in a biofilm. This research examined the effects of growth rate and substrate concentration on dual-species population densities in batch and biofilm reactors. In addition, the feasibility of using batch reactor kinetics to describe dual-species biofilm interactions was explored. The scope of the research was directed toward creating a dual-species biofilm for the biodegradation of trichloroethylene, but the findings are a significant contribution to the study of dual-species interactions in general. The two bacterial species used were Burkholderia cepacia PR1-pTOM(31c), an aerobic organism capable of constitutively mineralizing trichloroethylene (TCE), and Klebsiella oxytoca, a highly mucoid, facultative anaerobic organism. The substrate concentrations used were different dilutions of a nutrient-rich medium resulting in dissolved organic carbon (DOC) concentrations on the order of 30, 70, and 700 mg/L. Presented herein are single- and dual-species population densities and growth rates for these two organisms grown in batch and continuous-flow biofilm reactors. In batch reactors, planktonic growth rates predicted dual-species planktonic species dominance, with the faster-growing organism (K. oxytoca) outcompeting the slower-growing organism (B. cepacia). In a dual-species biofilm, however, dual-species planktonic growth rates did not predict which organism would have the higher dual-species biofilm population density. The relative fraction of each organism in a dual-species biofilm did correlate with substrate concentration, with B. cepacia having a greater proportional density in the dual-species culture with K. oxytoca at low (30 and 70 mg/L DOC) substrate concentrations and K. oxytoca having a greater dual-species population density at a high (700 mg/L DOC) substrate concentration. Results from this research demonstrate the effectiveness of using substrate concentration to control population density in this dual-species biofilm.

Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. II. Modeling

A strain of Pseudomonas putida that harbors plasmids RK2 and pDLB101 was exposed to a pure culture biofilm of Bacillus azotoformans grown in a rotating annular reactor. Transfer of the RK2 mobilizable pDLB101 plasmid to B. azotoformans was monitored over a 4-day period. Experimental results demonstrated that the broad host range, RSF1010 derivative pDLB101 was transferred to and expressed by B. azotoformans. In the companion article to this work, the rate of plasmid transfer was quantified as a function of the limiting nutrient, succinate, and as a function of the mechanism of transfer. A biofilm process simulation program (AQUASIM) was modified to analyze resultant experimental data. Although the AQUASIM package was not designed to simulate or predict genetic events in biofilms, modification of the rate process dynamics allowed successful modeling of plasmid transfer. For the narrow range of substrate concentrations used in these experiments, nutrient level had only a slight effect on the rate and extent of plasmid transfer in biofilms. However, further simulations using AQUASIM revealed that under nutrient poor conditions, the number of transconjugants appearing in the biofilm was limited.

Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. I. Experiments

A strain of Pseudomonas putida harboring plasmids RK2 and pDLB101 was exposed to a pure culture biofilm of Bacillus azotoformans grown in a rotating annular reactor under three different concentrations of the limiting nutrient, succinate. Experimental results demonstrated that the broad host range RSF1010 derivative pDLB101 was transferred to and expressed by B. azotoformans. At the lower concentrations, donor mediated plasmid transfer increased with increasing nutrient levels, but the highest nutrient concentration yielded the lowest rate of donor to recipient plasmid transfer. For transconjugant initiated transfer, the rate of transfer increased with increasing nutrient concentrations for all cases. At the lower nutrient concentrations, the frequency of plasmid transfer was higher between donors and recipients than between transconjugants and recipients. The reverse was true at the highest succinate concentration. The rates and frequencies of plasmid transfer by mobilization were compared to gene exchange by retrotransfer. The initial rate of retrotransfer was slower than mobilization, but then increased dramatically. Retrotransfer produced a plasmid transfer frequency more than an order of magnitude higher than simple mobilization.