RP-Department of Plant and Microbial Sciences

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Activity of East African Medicinal Plants against Helicobacter pylori
(Pubmed, 1996-09) Fabry, W.; Okemo, P. O.; Ansorg, Rainer
The activity of extracts from the East African medicinal plants Entada abyssinica (stem bark), Terminalia spinosa (young branches), Harrisonia abyssinica (roots), Ximenia caffra (roots), Azadirachta indica (leaves and stem bark) and Spilanthes mauritiana (roots and flowers) were evaluated against 12 strains of Helicobacter pylori. The most active extracts were those derived from T. spinosa with an MIC50 of 125 μg/ml, an MIC90 of 250 μg/ml and an MIC range of 62.5–500 μg/ml. An MIC50 of 250 μg/ml and an MIC90 of > 4,000 μg/ml was reached by H. abyssinica with a range of 125– > 4,000 μg/ml and by X. caffra with a range of 62.5– > 4,000 μg/ml, respectively. It is concluded that these plants contain compounds with antimicrobial activity against H pylori.
Activity of some medicinal plant extracts against fungal plant pathogens
(2012-04-25) Okemo, P. O.; Mwatha W. E.; Ngigi S.K.
Actors and networks in resource conflict resolution under climate change in rural Kenya
(Copernicus Publications, 2016) Ngaruiya, Grace W.; Scheffran, Jürgen
The change from consensual decision-making arrangements into centralized hierarchical chieftaincy schemes through colonization disrupted many rural conflict resolution mechanisms in Africa. In addition, climate change impacts on land use have introduced additional socio-ecological factors that complicate rural conflict dynamics. Despite the current urgent need for conflict-sensitive adaptation, resolution efficiency of these fused rural institutions has hardly been documented. In this context, we analyse the Loitoktok network for implemented resource conflict resolution structures and identify potential actors to guide conflict-sensitive adaptation. This is based on social network data and processes that are collected using the saturation sampling technique to analyse mechanisms of brokerage. We find that there are three different forms of fused conflict resolution arrangements that integrate traditional institutions and private investors in the community. To effectively implement conflictsensitive adaptation, we recommend the extension officers, the council of elders, local chiefs and private investors as potential conduits of knowledge in rural areas. In conclusion, efficiency of these fused conflict resolution institutions is aided by the presence of holistic resource management policies and diversification in conflict resolution actors and networks.
African Heritage in a Changing Climate
(Taylor & Francis, 2020) Brooks, Nick; Clarke, Joanne; Ngaruiya, Grace Wambui; Wangui, Elizabeth Edna
Climate change is a real and present threat to heritage across the world. In Europe and North America, research on the impacts of climate change on heritage, including how to mitigate against more frequent extreme weather events and how to implement efficient sustainable adaptation planning, are now key foci of heritage literature. In contrast, virtually nothing has been written about the impacts of climate change on heritage on the African continent, even though these will be significant in the coming decades. Heritage is essential for livelihoods, but also for the construction and reinforcement of identity and the psychological wellbeing of society. Here, we consider the impacts of climate change on different (connected) forms of heritage in Africa, including archaeological, historical and living heritage. We situate the implications of climate change for African heritage in recent debates around climate justice, sustainability and social wellbeing. We conclude that without significant intervention some of Africa’s most important heritage will be lost as a result of the direct and indirect impacts of climate change over the coming decades. Our intention is to draw attention to the need for research into the impacts of climate change on different forms of heritage in Africa and to highlight the possible deleterious effects these losses will have on society more generally. We view this paper as a first step in developing a research agenda that will have a practical application for the management of heritage in the face of climate change in Africa.
Agrobacterium -mediated genetic transformation of selected tropical inbred and hybrid maize ( Zea mays L.) lines
(Plant Cell Tiss Organ Cult, 2012-10-25) Ombori, O.; Muoma, John Vincent Omondi; Machuka, Jesse
The study was carried out to evaluate the amenability of tropical inbred and hybrid maize lines, using Agrobacterium mediated transformation technique. Agrobacterium tumefaciens strains EHA101 harbouring apTF102 binary vector, EHA101, AGL1, and LBA4404 harbouring pBECK2000.4 plasmid, LBA4404, GV and EHA105 harbouring pCAMBIA2301 plasmid, and AGL1 harbouring the pSB223 plasmid were used. Delivery of transgenes into plant tissues was assessed using transientb-glucuronidase (gus) activity on the 3rd and 4th day of co-cultivation of the infected Immature Zygotic Embryos (IZEs) and embryogenic callus. Transient gus expression was influenced by the co-cultivation period, maize geno-type and Agrobacterium strain. The expression was highest after the 3rd day of co-culture compared to the 4th day with intense blue staining was detected for IZEs which were infected with Agrobacteriumb strains EHA105 har-bouring pCAMBIA2301 and EHA101 harbouring pTF102 vector. Putative transformants (To) were regenerated from bialaphos resistant callus. Differences were detected on the number of putative transformants regenerated among the maize lines. Polymerase chain reaction (PCR) amplifica-tion of Phosphinothricin acetyltransferase (bar) and gus gene confirmed the transfer of the transgenes into the maize cells. Southern blot hybridization confirmed stable inte-gration of gus into PTL02 maize genome and segregation analysis confirmed the inheritance of the gus. A transfor-mation efficiency of 1.4 % was achieved. This transfor-mation system can be used to introduce genes of interest into tropical maize lines for genetic improvement.
Agrobacterium-Mediated Transformation of Selected Kenyan Maize (Zea mays L.) Genotypes by Introgression of Nicotiana Protein Kinase (npk1) to Enhance Drought Tolerance
(Scientific Research Publishing, 2014) Omwoyo, Ombori; Muoma, J.O.
Currently maize production in the East and Central Africa (ECA) region is at 1.3 tonnes per hectare compared to the potential of up to 7.0 tonnes per hectare because of biotic and abiotic constraints, and this has resulted in prevalence of famine in sub-Saharan Africa. Drought is the most important abiotic stress affecting productivity of maize in Sub Saharan Africa leading to up to 70% crop loss and in certain cases total crop loss. Previous work has shown that Mitogenic Activated Protein Kinase (MAPKKK) gene activated an oxidative signal cascade, which led to tolerance to adverse condition. To analyze the role of the oxidative signal cascades on tropical maize, 4 transgenic tropical maize plants were developed through an Agrobacterium-mediated transformation with a MAPKKK homology from tobacco Nicotiana Protein Kinase 1 (npk1) and the insert was confirmed using Southern and Northern blot hybridization analysis. Fertile To maize plants were obtained which were planted to generate T1 plants, which were used for comparison with non-transgenic plants. The T1 plantlets of tropical inbred TL08-(2)4, single hybrid cross of a PTL001, a multiple cross hybrid DH01 and a dry land cultivar DLC1 genotypes were planted in the greenhouse and assessed for morphological and physiological changes associated with increase in drought stress tolerance when under water stress condition. The results showed that npk1 effectively enhanced drought tolerance in TL08-(2)4 and PTL001, and there was no significant morphological difference between transgenic controls (well watered) and transgenic tests (subjected to moderate drought stress). Overall, there were between 20% - 35% enhancements of yield of the transgenic stressed events compared with non-transgenic stressed control
Agrobiodiversity conservation enhances food security in subsistence‑based farming systems of Eastern Kenya
(BioMed Central, 2016) Mburu, Simon Wambui; Koskey, Gilbert; Kimiti, Jacinta Malia; Ombori, Omwoyo; Maingi, John M.; Njeru, Ezekiel Mugendi
Background: Globally, there is great concern about expanding agricultural activities due to their impact in the conservation of agrobiodiversity. African continent is known for its richness in biodiversity. In Kenya, there is a continuous unabated expansion of agriculture into natural habitats due to demographic and economic pressures posing a significant threat to biodiversity. Therefore, there is a need to study biodiversity loss and its regain through practices in agricultural landscapes. In this study, we assessed the status of agrobiodiversity and its contribution to food security in four agroecological zones of Eastern Kenya. Sixty households were sampled from two selected agroecological zones (upper and lower midland zones) in Embu and Tharaka-Nithi counties. Structured questionnaires and checklists were used to collect the data. Results: Thirty-nine crop species were identified dominated by vegetables, fruits, legumes and cereals with relative densities of 28.8, 20.5, 18.3 and 8.3 %, respectively. Embu Lower Midland and Tharaka-Nithi Lower Midland zones had relatively higher crop species richness of 243 and 240, respectively, and Shannon–Wiener diversity indices (H′) of 3.403 and 3.377, respectively, compared with Embu Upper Midland and Tharaka-Nithi Upper Midland zones with species richness of 229 and 207, respectively, and H′ of 3.298 and 3.204, respectively. Conclusions: Households from lower midland zones with high crop diversity and richness were more food secure compared with those from the Upper Midland zones with low crop diversity and richness. These findings suggest that farm production systems with high agrobiodiversity contributed more toward food security among smallholder farmers in the selected sites. Keywords: Agrobiodiversity, Food security, Biodiversity loss, Smallholder farmers, Kenya
Agronomic performance, genetic variation and heritability of yield and related traits in rice genotypes under upland conditions
(2022-06) Al-Imran, D.1; Musila, R. N.; Kamau, W. J.
Although rice production potential under rain fed ecology doubles that of irrigated lowland in Kenya, there has been little advancement in identifying suitable varieties adapted to upland rice ecology. This study was carried out to appraise the agronomic performance, heritability, grain yield components, genetic variability, and correlations for grain yield and identity of suitable varieties for the upland ecology. Eight rice genotypes were evaluated in a randomized complete block design alongside three replicates under upland conditions. Collection of data included days to 50% flowering, height of the plant, productive tillers-1, panicle length, grain length, panicle weight, grains panicle-1, spikelet fertility, grain yield weight of one thousand grains, grain breadth and breadth/ length ratio of the grain. Data analysis involved Analysis of variance, broad sense heritability estimates determination and principal component analysis. Genotype’s variation was significant for all traits measured. The first three principal components accounted for 94.67% of the sum variation among 12 traits under study. The outcome of heritability estimates and the PCA indicated that the characters 50% flowering days, weight of a thousand grains, spikelet fertility, length of the panicle, grain breadth, length of the grain and breadth/length ratio, accounted for most of variance in the variables observed and showed average to high broad sense heritability. Therefore, for these traits, early generation selection was effective in identifying superior genotypes following hybridization. From the eight cultivars used in the study, NERICA 10 and NERICA 2 varieties had better indicators for coastal lowlands of Kenya.
Agronomic performance, genetic variation and heritability of yield and related traits in rice genotypes under upland conditions
(Kenyatta University, 2022-06) Al-Imran, D.; Ruth, N. M.; Kamau, W. J.
Although rice production potential under rain fed ecology doubles that of irrigated lowland in Kenya, there has been little advancement in identifying suitable varieties adapted to upland rice ecology. This study was carried out to appraise the agronomic performance, heritability, grain yield components, genetic variability, and correlations for grain yield and identity of suitable varieties for the upland ecology. Eight rice genotypes were evaluated in a randomized complete block design alongside three replicates under upland conditions. Collection of data included days to 50% flowering, height of the plant, productive tillers-1, panicle length, grain length, panicle weight, grains panicle-1, spikelet fertility, grain yield weight of one thousand grains, grain breadth and breadth/ length ratio of the grain. Data analysis involved Analysis of variance, broad sense heritability estimates determination and principal component analysis. Genotype’s variation was significant for all traits measured. The first three principal components accounted for 94.67% of the sum variation among 12 traits under study. The outcome of heritability estimates and the PCA indicated that the characters 50% flowering days, weight of a thousand grains, spikelet fertility, length of the panicle, grain breadth, length of the grain and breadth/length ratio, accounted for most of variance in the variables observed and showed average to high broad sense heritability. Therefore, for these traits, early generation selection was effective in identifying superior genotypes following hybridization. From the eight cultivars used in the study, NERICA 10 and NERICA 2 varieties had better indicators for coastal lowlands of Kenya.
Analysis of Combining Ability for Early Maturity and Yield in Rice (Genus: Oryza) At the Kenyan Coast
(Hindawi Limited, 2020) Dianga, Al-Imran; Joseph, Kamau W; Musila, Ruth N
(e main challenges facing rain-fed rice farming in Kilifi County at the Kenyan coast are inadequate and erratic rainfall, inadequate skills, and poorly developed infrastructure. Of great importance is erratic rainfall that tends to depress towards the end of long rain season, leading to crop failure. Combining ability analysis is one of the most valuable tools used to ascertain gene action effects and help in selecting desirable parents for making crosses and coming up with high yielding and early maturing lines. Combining ability for early maturity and yield has not been studied at the Kenyan coast. (is study aimed at determining and identifying good, general, and specific combiners for selecting better parents and better cross combinations in rice crops for developing high yield and short duration lines in rain-fed rice farming. Seven lines were subjected to half-diallel mating design at the Kenya Agricultural and Livestock Research Organization (KALRO), Mtwapa, and at Bahari in Kilifi town. Evaluation for general combining ability (GCA) and specific combining ability (SCA) analysis was done. Combining ability variance and GCA and SCA effects were determined. Based on GCA effects, best parent for early maturity was Dourado Precoce, while for yield, Supaa, Komboka, and NERICA 10. SCA estimates indicated that best crosses for yield were D/S, D/N1, and K/N10, while the best performing cross for early maturity was D/N1.
Analysis of the cyanotoxins anatoxin-a and microcystins in Lesser Flamingo feathers
(Taylor & Francis, 2014-05-30) Kotut, K.; Pütz, S.; Krienitz, L.; Ballot, A.; Eberhard, Krause; Wiegand, C.; Pflugmacher, S.; Codd, G. A.
Feathers from carcasses of the Lesser Flamingo (Phoeniconaias minor), which had died after ingesting cyanobacterial toxins (cyanotoxins) contained between 0.02 and 30.0 µg microcystin-LR equivalents per gram of feather according to HPLC and ELISA analysis of feather extracts. Anatoxin-a was detected less frequently in the Lesser Flamingo feathers, up to 0.8 µg anatoxin-a per gram of feather being recorded. When feathers from different body regions were analysed and compared for microcystins and anatoxin-a, wing feathers were found to contain the highest concentrations of these cyanotoxins, the order of concentration and frequency of analytical detection being wing > breast > head. Consistent with the presence of the microcystins and anatoxin-a in gut contents and the livers of the dead birds and negligible in vitro adsorption to feathers, the cyanotoxins associated with the feathers of the dead wild flamingos are inferred to be primarily of dietary origin.
Analysis of the Effects of Di-Electric Heating on Common Food Bacterial Pathogens: Evaluation Based on Antibiotic Susceptibility and Infective Doses
(2013-08) Okemo, P. O.; Luvanda, M. K.; Maingi, John; Yang, E.
In this study, various food samples (n=73) artificially infected by food borne disease pathogens ( Escherichia coli,Staphylococcus aureus, Shigella flexneri and Salmonellaenterica spp. paratyphi) were exposed to microwave radiation at different powers (P-00, P-20, P-40, P-60, P-80) and time periods (2 min, 4 min, 6 min, 8 min).The degree of inactivation was estimated by measuring the colony forming units formed in culture before and after exposure of samples to radiation. The data showed that microwave radiation produced a 1-2 log reduction when infected food samples were processed. Initial seeded bacterial numbers (>3.0 x 104) were reduced significantly (P<0.05). The most effective power-time combination for bacteria inactivation was 8 minutes at P-80 (1180W) where bacteria numbers were very low (<1.0 x 103); whereas the least effective power-time combination for bacteria inactivation was 2 minutes at P-20 (295W) where bacteria numbers remained at (>3.0 x 104). The study shows that microwave radiation reduces infective doses of bacteria but does not have any significant effect on their antibiotic susceptibility patterns.
Antagonistic Plants
(Taylor & Francis, 2013-05-29) Owino, P. O.
Control of nematodes has been mainly through the use of chemicals and host resistance. However, the existence of physiological races in the pathogen's population has complicated efforts to breed for resistant cultivars. Interest in developing alternative control measures that are safe and economically attractive has now intensified worldwide. The use of antagonistic plants is viewed as a viable nematode management option.
Anti-Mycobacterial and Toxicity Activities of Some Priority Medicinal Plants from Lake Victoria Basin, Tanzania
(SCIENCEDOMAIN international, 2012-02) Magadula, Joseph J.; Otieno, Joseph N.; Nondo, Ramadhani S.; Kirimuhuzya, Claude; Kadukuli, E.; Orodho, John Aluko; Okemo, P. O.
Aims: This study has evaluated ethanol extracts from five medicinal plants selected through ethnobotanical study from Lake Victoria basin, Tanzania for their in vitro anti- mycobacterial activity against two Mycobacterium species and cytotoxicity against brine shrimp larvae. Study Design: Laboratory experimental tests. Place and Duration of Study: Institute of Traditional Medicine, Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, Tanzania, between July 2010 and July 2011. Methodology: Five medicinal plants were selected from the priority list obtained from Lake Victoria basin, Tanzanian side. Collection, processing and drying of plant samples were done in the field with the assistance of a botanist while extraction and concentration of plant samples to obtain crude extracts were done in the laboratory following standard procedures. The plants included in this study are Antidesma membranaceum, Crassocephalum manii, Entada abyssinica, Croton dichogamus and Rubia cordifolia. The two fold microdilution method was used to determine the MIC values of extracts against two Mycobacterium marker strains (Mycobacterium indicus pranii and Mycobacterium madagascariense). The cytotoxicity of plant extract was evaluated against brine shrimp larvae. Furthermore, the extracts were screened phytochemicaly to establish the group of compounds responsible for the activity. Results: Among the tested extracts, the stem bark of A. membranaceum and C. manii showed moderate to mild activity against M. indicus pranii (MIC = 0.3125 mg/ml) and M. madagascariense (MIC = 0.625 mg/ml) respectively. Furthermore, A. membranaceum exhibited significant toxicity activity with LC50 value of 36.134 µg/ml against brine shrimp larvae. Other plants were moderately active when tested in vitro against the above organisms. Phytochemical screening of extracts indicated the presence of different classes of compounds. Conclusion: This study has shown the potential of the priority medicinal plant extracts to be the source of possible lead compounds and anti‐TB drug candidates needed for the management of Tuberculosis. Isolation of active principles from active fractions will be further undertaken.
Antibacterial activity of Apis mellifera L. propolis collected in three regions of Kenya
(SCIELO Brasil, 2007-08) Muli, E.M.; Maingi, J.M.
The present study aimed at investigating the susceptibility of the microorganisms Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis to ethanolic extracts of propolis (EEP) from three regions of Kenya (Taita, Tana and Samburu). Propolis was extracted using four different concentrations of ethanol: pure, 70%, 50%, and 30%. Ethanol (70%) and Streptomycin were used as controls. The agar diffusion method using filter paper disks was employed. Antibacterial activity was determined as an equivalent of the inhibition zones diameters (in millimeters) after incubation at 37°C for 24h. Significant differences in the antibacterial activities of propolis were observed among the three regions, depending on the test microorganisms and on the procedure used for the preparation of propolis extract. Bacillus subtilis and Staphylococcus aureus were the most susceptible bacteria and 70% EEP had the best antibacterial effect.
Antibacterial activity of East African medicinal plants
(Science Direct, 1998-02) Fabry, W.; Okemo, P. O.; Ansorg, R.
In an ethnopharmacological survey, extracts of the six East African medicinal plants Entada abyssinica (stem bark), Terminalia spinosa (young branches), Harrisonia abyssinica (roots), Ximenia caffra (roots), Azadirachta indica (stem bark and leaves), and Spilanthes mauritiana (roots and flowers) were tested against 105 strains of bacteria from seven genera (Staphylococcus, Enterococcus, Pseudomonas, Escherichia, Klebsiella, Salmonella, Mycobacterium). The minimum inhibitory concentration reached by 50% (MIC50%) and 90% (MIC90%) of the strains for the extracts of E. abyssinica, T. spinosa, X. caffra, and A. indica (stem bark) ranged from 0.13–8 mg/ml and from 0.5 to >8 mg/ml, respectively. Their minimum bactericidal concentration by 50% (MBC50%) and MBC90% were all between 0.5 and >8 mg/ml. H. abyssinica, A. indica (leaves), and S. mauritiana (roots and flowers) had MIC and MBC values ≥8 mg/ml. Mycobacteria were not inhibited at extract concentrations of 0.5–2 mg/ml. lt is concluded that plant extracts with low MIC and MBC values may serve as sources for compounds with therapeutic potency.
Antibacterial Activity of Tabernaemontana Stapfiana Britten (Apocynaceae) Extracts
(PMC, 2009-03-07) Okemo, P. O.; Lucas, K. Karimie; Machocho, Alex K.; Christine, C. Bii; Paul, K. Tarus; Ernest, K. Ruttoh
Antibacterial and phytochemical screening of methanolic, sequential extracts (hexane, dichloromethane, ethyl acetate and methanol) and alkaloid rich fractions of Tabernaemontana stapfiana Britten was carried out. The phytochemical screening showed the presence of alkaloids, flavonoids, coumarins, tannins and saponins that have been associated with antimicrobial activity. The stem and root bark methanolic extracts showed good activity against the bacterial strains used including the multiple drug resistant Staphylococcus aureus strain with minimum inhibitory concentrations ranging from 15.6 to 500 µg/ml and minimum bactericidal concentrations ranging from 31.25 to 500 µg/ml. The sequential extracts of the root and stem bark had high antimicrobial activity with minimum inhibitory concentrations (MICs) ranging between 3.9 and 250 µg/ml and minimum bactericidal concentrations (MBCs) ranging between 7.8 and 500 µg/ml against the tested microorganisms. The dichloromethane extract of the alkaloid rich fractions however exhibited reduced antibacterial activities as compared to methanol and sequential extracts but the dichloromethane:methanol (4:1) mixture showed high activity with MICs ranging between 15.6 and 250 µg/ml. These antibacterial efficacy studies suggest that Tabernaemontana stapfiana Britten could be a source of antibacterial agents.
Antibacterial activity of tabernaemontana stapfiana britten (apolynaceae) extracts
(African ethnomedicines, 2009) Ruttoh, Ernest K.; Tarus, Paul K.; Biic, Christine C.; Machocho, Alex K.; Karimi, Lucas K.; Okemo, P. O.
The resistance of bacteria and fungi to antimicrobial agents is a world-wide medical problem (WHO, 2004). Currently there are emerging multiple drug resistant (MDR) typhoid outbreaks, especially in developing countries. Tuberculosis is also becoming an unstoppable epidemic due to MDR strains that have emerged. In addition to these, there are many bacteria that have developed drug resistance including Staphylococcus aureus and most of the Enterobacteriaceae, such as Klebsiella pneumoniae (WHO, 2004). More than 70% of the bacteria causing infections are resistant to at least one of the drugs commonly used to treat them (WHO, 2004). This situation has been worsened by HIV/AIDS pandemic, poverty, an upsurge of new and re-emerging infectious diseases, high costs and side effects of available drugs (Humber, 2002). This has resulted in increased severity of infectious diseases and high mortality rates from certain infections. All these have necessitated studies on potential sources of effective, safe and cheap antimicrobial alternatives, and plants are one of these sources that have not been exhaustively utilized (Thangadurai et al., 2004). The genus Tabernaemontana comprises of about 100 species distributed throughout the tropical regions of the world (Grover, et al., 2002). Tabernaemontana stapfiana Britten is a tree of up to 21 meters high and commonly found in disturbed forests (Beentje, 1994). Information obtained from Keiyo traditional medical practitioners in Kenya indicate that this plant is locally known as “mobonet” and its roots and stem barks are used in the treatment of abdominal problems, sexually transmitted infections and upper respiratory tract infections (Omino and Kokwaro, 1993). The fruits of this plant are edible. There has been no systematic study on T. stapfiana with no information reported on chemical and biological studies. In this study, the methanolic extracts of leaves, root, and stem barks and the sequential (hexane, dichloromethane, ethyl acetate and methanol) extracts were assayed for antibacterial activity and screened for phytochemicals. The alkaloid rich fractions were also assayed against selected bacterial test organisms.
Antibacterial and Antifungal Activities of Essential Oils from Satureia Biflora D. Don, Benth, Speng (Chepsagitiet). Lippia Javanica Burm. F.(Labotuet) and Toddalia asiatica (L) Lam. Rutaceae (Chepindoruet)
(Global Journals Inc, 2014) Okemo, P. O.; Omari, Amuka; Machocho, Alex K.; Mbugua, Paul K.
Three plants, parts used, by the Ogiek community as medicines were collected from Marioshoni in the Mau Forest Complex in the Rift Valley of Kenya, idenfied at the National Museums in Nairobi; S. biflora Voucher No.AO/08/12/12/2006 L. javanica O/015/NMK/06/12/2007 T. asiatica Voucher No. AO/017/NMK/04/07/2007. Each plant species was steam distilled individually. All yielded oils that were separately assayed against some known pathogens that inflict maladies in humans. The two species showed some markable antimicrobial activities for instance, S. biflora was effective against S. aureus, K. pneumoniae and E. coli including all their drug resistant strains. The essential oils from all the three plant species possessed activities against all the strains of S. aureus, different zones of inhibitions L. javanica is amongst other medicinal essential oils that have been studied elsewhere and proved useful medically. However, S. biflora which has varied activities when screened in the laboratory in vitro has not been studied exhaustively. The plant oil extracts gave promising results against both Gram-ve and Gram +ve bacteria. T. asiatica showed good activities against the bacteria and some known pathogenic fungi Further studies on wet bench chemistry and GC showed known classes of compounds which are of known medicinal values
Antibacterial Effect of Artemisia and Ginger Extracts in Controlling Agrobacterium Tumefaciens in Roses
(Update Publishing House, 2021) Njagi, Alfred; Nyamwange, Methuselah Mang’erere; Njeru, Ezekiel Mugendi; Birgen, Jonah Kiprono
Rose is the world’s most traded cut flowers with 74 % being produced in Kenya. Pests like spider mites, caterpillar, aphids, thrips, nematodes and diseases such as crown gall, downy mildew, powdery mildew and botrytis highly compromise rose production. Crown gall disease caused by Agrobacterium tumefaciens is the most problematic disease of roses in Kenya, causing production loss of up to 60 % depending on the age and variety of rose. An experiment to determine the antibacterial effect of Artemisia and ginger extracts was carried out in vitro, where the inhibitory zones around filter discs soaked with extracts on Muller Hinton agar was established. The extracts were emulsified with dimethylsulfoxide (50 %) and minimum inhibitory concentrations of Artemisia (125 mg/ml), ginger (62.5 mg/ml) and mixture of Artemisia and ginger (31.25 mg/ml) were used to soak the filter discs whereas the commercial recommended rate of copper hydroxide of 6.25 mg/ml was used. Artemisia and copper hydroxide (commercial antibiotic) had highest inhibition zone of 12.80 mm compared to ginger 10.60 mm. Mixture of Artemisia and Ginger had slightly lower inhibition zone (10.20 mm) though not significantly different from ginger (P> 0.001). An eight-month greenhouse experiment was also done to determine the efficacy of the extracts on inoculated rose plants. The results showed that crown gall incidence and gall weight were low but not significantly different from copper hydroxide and Artemisia. Crop vigor, which was indicated by stem length was highest for Artemisia treatment with an average of 73.54 cm followed by copper hydroxide (67.25 cm) while ginger and mixture of ginger and Artemisia had 53.44 cm and 64.70 cm respectively. From the results of this research, Artemisia and Ginger extracts are promising alternative to control crown gall and possibly other diseases in field crops. Artemisia performance compares well with copper hydroxide and therefore the best alternative to replace copper hydroxide.

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