The aim of this work was to study spatial evolution of the chemotaxis proteins of a group of plant-associated soil-dwelling bacteria vernacularly referred to as the B. subtilis group. This was achieved by creating homology models for the chemotaxis proteins if a suitable template was available, and by analysing the selective forces (positive, purifying or neutral) acting upon the chemotaxis proteins. Chemotaxis is the phenomenon in which bacteria direct their movement towards more favourable conditions, and is critical for processes such as obtaining nutrients, escaping toxic compounds, host colonization and bio-film formation. Members of the B. subtilis group exhibit different preferences for certain host plants, and it is therefore feasible that their chemotactic machinery are fine-tuned to respond optimally to the conditions of the various niches that the strains inhabit. Homology models were inferred for the plant growth promoting B. amyloliquefaciens FZB42 proteins CheB, CheC, CheD, CheR, CheW and CheY. The interactions between: CheC-CheD, the P1 and P2 domains of CheA with CheY and CheB, and the P4 and P5 domains of CheA with CheW were also modelled. The hydrophobic interactions contributing to intra- and inter-protein contacts were analysed. The models of the interactions between CheB and the various domains of CheA are of particular interest, because to date no structures have been solved that show an interaction between a histidine kinase (such as CheA) and a multidomain response regulator (such as CheB). Furthermore, evidence that phospho-CheB may inhibit the formation of phospho-CheY by competitively binding to the P2 domain of CheA is also presented. Proteins were analysed to determine if individual amino acid sites are under positive, neutral or purifying selection. The Methyl Accepting Chemotaxis Proteins (MCPs), CheA and CheV were also analyzed, but due to a lack of suitable templates, no homology models were constructed. Site-specific positive and purifying selection were estimated by comparing the ratios of non-synonymous to synonymous substitutions at each site in the sequences for the chemotaxis proteins as well as for the receptors McpA, McpB, and McpC. Homology models were coloured according to intensity of selective forces. It was found that the chemotaxis proteins of member of the B. subtilis group are under strong evolutionary constraints, hence it is unlikely that positive selection in these proteins are responsible for the differences in habitat preference that these organism exhibit.

Acompanha memorial / Tese (livre-docencia) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-16T08:07:42Z (GMT). No. of bitstreams: 1 Habib_MohamedEzzEl-DinMostafa_LD.pdf: 6621704 bytes, checksum: f55463be23eb86b925f2eacb9517e66e (MD5) Previous issue date: 1982 / Resumo: A patogenicidade de duas variedades de Bacillus tnuringiensis Berliner foi investigada em larvas de Lepi-doptera e Diptera. Através do enfoque patológico no estudo, tentou-se esclarecer alguns aspectos importantes nas áreas de pesquisa, industrialização de patógenos e aplicação de produtos à base de B. thuringiensis no campo. Os sintomas externos pré-mortais foram descritos em larvas de Lepidoptera infectadas por B. thuringiensis var. kurstaki e em larvas de Diptera infectadas por B. thuringien-sis var. israelensis. Algumas alterações histológicas foram detectadas em alguns tecidos de tais larvas, principalmente , no intestino médio, sistema nervoso e musculatura. As alterações observadas nesses tecidos foram relacionadas com o desencadeamento dos sintomas externos da bacteriose. A variedade kurstaki teve ação fatal lenta (2 a 3 dias) nas larvas de Lepidoptera, quando comparada com a ação da variedade israelensis nas larvas aquáticas de Diptera,onde a morte ocorre em poucas horas após a infecção. Nenhum dos lepidópteros estudados pertence o tipo I da classicificação de Heimpel & Angus (1959); pois não ocorreu paralisia geral ou aumento no pH da hemolinfa nas larvas doentes. Entre as larvas dessas espécies, as de Brasso-lis sophorae revelaram-se mais susceptiveis em relação às demais. Por outro lado, as larvas de Spodoptera latifascia e-ram as mais resistentes à mesma variedade kurstaki ( sorotipo H-3a:3b). A origem do patógeno, o hospedeiro do qual este foi isolado e o processamento da produção comercial, além da variedade do bacilo e da espécie do inseto infectado, eram fatores responsáveis pela variação nas respostas das larvas infectadas. A expressão da quantidade do patógeno em termos de Unidades Internacionais de virulência / unidade de peso do inseto tratado revelou-se altamente precisa para comparações de susceptibilidade de insetos e virulência de produtos. 0 uso de critérios de DL50 e CL50 _ mostrou-se muito adequado, e até pode ser recomendado, para estudos com populações de insetos geneticamente menos variáveis. A resposta dos indivíduos, no caso, seria diretamente relacionada com e em função da dose ou a concentração aplicada. 0 uso de TL50 , por outro lado, revelou-se mais funcional e, também, pode ser recomendado para investigações com populações de maior variabilidade genética. Os níveis de susceptibilidade revelados para cada uma das espécies estudadas, indicaram a alta possibilidade de obter resultados satisfatórios no campo, quando produtos comerciais à base da variedade kurstaki forem aplicados contra larvas de B. sophorae , Alabama argillacea e Plodia inter-punctella em jardins e áreas urbanas, lavoura e armazéns respectivamente. A morte iniciou-se, nas larvas aquáticas dos dípteros estudados, apenas poucas horas após a infecção pela variedade israelensis. As larvas de Culex declarator (Culicidae) mostraram-se mais susceptíveis a essa variedade do que as lar vas de simulídeos, quando infectadas com este patógeno. Entre as duas espécies de simulídeos, as larvas de Simulium goeldii eram 4 vezes mais susceptíveis do que as de S. rorotaense. As larvas do último estádio de C. declarator revelaram-se mais susceptíveis ao patógeno do que as dos estádios iniciais. No mesmo tempo, as larvas no início do último estádio (42) eram mais susceptíveis do que no final do mesmo estádio. Este último aspecto, juntamente com a morte rápida causada pelo patógeno ( 2 a 3 horas), devem ser considerados nas recomendações de alguns órgãos oficiais no exterior. Tais órgãos, exigem que o 42 estádio larval de Aedes aegypti seja usado nos bioensaios de padronização de produtos à base da variedade israelensis ; porém, sem estabelecer uma fase desse estádio. A especificidade e a alta virulência da variedade israelensis para larvas aquáticas de Diptera, revelam o seu grande valor como agente promissor no controle microbiano de larvas de Culicidae e Simuliidae. Os sintomas externos observados nas larvas de. C. declarator, as alterações nistológicas e a morte rápida foram suficientemente convenientes para mostrar a ação da S-endo toxina produzida pelo patógeno. Tal toxina deve ter afetado drasticamente o sistema nervoso e a musculatura da larva, dificultando assim a manutenção desta na superfície da água e conseqüentemente a sua respiração do ar atmosférico. Assim , a larva afundada morreu por asfixia. Esses estudos revelaram a presença de um novo campo para investigações de patologia de insetos e controle microbiano para os dípteros aquáticos neotropicais e subtropicais . Tais investigações terão o seu alto valor do ponto de vista humano, desde que várias dessas espécies tem a sua importância como insetos vetores de doenças humanas / Abstract: The pathogenicity of two varieties of Bacillus thuringiensis Berliner was investigated using some lepi-dopterous and dipterous larvae. The aim of the present study was to clarify certain aspects related to the application of insect pathology, such as susceptibility and virulence évalua tions, standardisation criteria, and field applications of microbial products to the control of some harmful insects. The sequence of external symptoms was described in lepidopterous larvae infected with the B. thuringiensis var. kurstaki (syrotype K-3a:3b) and in dipterous larvae infected with the variety israelensis (syrotype H-14)-The histological alterations, in these infected larvae, were described, principally those in the mid-gut, nervous system, and musculature These alterations were found to be directly associated with the different external symptoms of the disease. The progress of the disease up to the death in the lepidopterous larvae lasted longer time (2-3 days) than in dipterous ones (2-3 hours). Type I of Heimpel & Angus (1959) classification did not occur among the lepidopterous species studied, since nei_ ther general paralysis nor pH alterations in the hemolymph were detected. Brassolis sophorae larvae were found to "be the most susceptible to syrotype H-3a:3b, when compared with the other lepidopterous species. On the other hand, Spodoptera lati-fascia larvae were the most resistant. Origin, natural host, and mass production criteria of the pathogen, in addition to its variety and the tested insect species, were the most important factors responsible for the variation in responses of the infected larvae. Therefore, these aspects should be considered to choice the more adequate product for each insect species to be combatted. The quantity of the pathogen expressed in International Units of toxicity per unit of body weight, showed to be highly precise for the comparison of insect susceptibility and pathogen virulence. The LD^Q and LC^0 criteria were found to be suitable and, therefore, can be recommended for investigations where the populations of insects are of low genetic variability. On the other hand, for genetically variable populations, the LT^q was found to be more adequate. B. sophorae, Alabama argillacea and Flodia inter-punctella were found to be highly susceptible to the syrotype H-3a:3b. Therefore, this pathogen can be recommended for their control. The aquatic dipteran larvae, studied in the present work, died some hours after infection with syrotype H-14.Culex declarator (Culicidae) larvae were more susceptible than those .132 . of the simulid species. Within Simuliidae, Simulium goeldii larvae were 4 times more susceptible than the S_. rorotaense ones. The last instar (4th.) larvae of C. declarator were more susceptible than those of the first instars. Moreover, within the same instar, these larvae showed different levels of susceptibility. In the initial phase of the last instar they were more susceptible than in the final phase. These informations, in addition to the rapid fatal action of the toxin in dipteran aquatic larvae, should be considered by the governamental agencies, in establishing standardization criteria for future commercial products based on this variety.At the present, these agencies establish the 4th instar larvae of Aedes aegypti as a test insect for stadardization bio-assays, ignoring the difference in susceptibility within the same instar. Because of the high specificity and virulence of B. thuringiensis var. israelensis for dipteran aquatic larvae, it can be considered as a promissing agent for microbial control of mosquitos and black flies larvae. Considering the mode of action of syrotype H-14 in mosquito larvae, the results led us to beleive that the £-endotoxin liberated in the high alkaline mid-gut affected the ventral nervous system and consequently the musculature , provoking disfunction of the latter.The effect on the muscles made the larva lose its capacity to maintain itself at the water surface. Consequently, the larva submerged and died by asphixiation. The observed sequence of the external symptoms, as well as the histological alterations sustained this hypothesis. The results obtained in the present study reveal the possibility to utilize the syrotype H-14 in the control of vectors of some human diseases, such as malaria and filaria This application, however, requires additional extensive research work to complete urgently needed informations / Tese (livre-docencia) - Univer / Livre-Docente em Ciencias Biologicas

A search of the literature revealed few references to the normal enteric flora of non-human vertebrates in general and the llama, Lama glama, in particular. The bacteriologic flora of the llama as a research project was suggested by my major professor, Dr. Fuad M. Nahhas, after it was brought to his attention by one of his assistants in the microbiology department of Dameron Hospital (Stockton, CA) that her pet llama was suffering from diarrhea. Fecal material from the llama was cultured and Yersinia enterocolitica was recovered. At the same time normal bacterial flora resembling those isolated from human material were also found. In seeking a research project I thought a bacteriologic examination of fecal material from llamas would be of some interest. A search of the literature revealed a great deal of information about parasitic infections of the llama, particularly by South American parasitologists and veterinarians,. but little information on the bacteriologic flora. Most of the published reports discuss enteric pathogens and enteric diseases (Fowler, 1989). Equally scarce are reports on the antibiotic pattern of such isolates; most reports on antimicrobial activity are limited to determining which drugs are effective in the treatment of a particular infection (Timoney et al, 1988). In contrast with this, Gram negative isolates from human intestinal material are well known and their antibiograms well documented in the literature as well as in unpublished hospital records. The use of antibiotics, discriminately or indiscriminately, in the treatment of human infections and the addition of antibiotics, especially tetracycline, to animal feeds to promote growth have led to the emergence··of resistant strains among these bacteria. To what extent such resistance exists in, has crossed over to, or has been exchanged among the intestinal isolates of humans and other vertebrates is not known. The objective of this study is, therefore, twofold: 1) to conduct a survey of the Gram negative aerobic intestinal bacterial flora of llamas to determine what species are present and their relative abundance; 2) to compare their biochemical (biotypes) and antibiotic patterns (antibiogram) with isolates from other animals and humans where information is available.

Work on the isolation of Bacillus albolactis from milk, and studies of it in pure culture, indicated the presence of two main colonial varieties. / Master of Science

The goals of this research were 1) to provide nutritional information that would be useful for the classification of Bacillus sphaericus, a heterogenous bacterial species, 2) to determine nutritional characteristics that would assist in the design of a selective medium for the mosquito pathogenic strains of B. sphaericus and 3) to determine the effect of carbon supplementation of complex media on sporulation and mosquito toxicity of B. sphaericus. In general, the pathogenic strains which constitute DNA homology group IIA of the species, grew with a greater variety of compounds as sole carbon sources than did the non-pathogenic strains of the other homology groups. Within homology group IIA, strains of phage group 3, which are the most toxic, grew with the largest number of compounds as sole carbon sources. However, the nutritional characteristics did not allow the unequivocal differentiation of any one DNA homology group or phage group from all of the other groups. It was possible to differentiate a DNA homology group or phage group from some of the other groups. A defined medium containing malate and acetate as carbon sources was found to enable the cells to produce 1.1x10⁸ spores/ml and thus would be useful for studying the physiology of sporulation. Eighteen of 22 pathogenic strains were capable of growth in a liquid, defined medium with arginine as the sole carbon source, while only 2 of 17 non-pathogenic strains were capable of growth under these conditions. Thus, arginine may be useful as the carbon source in a selective medium for the mosquito pathogenic strains. Of several compounds which could be used by B. sphaericus as sole carbon sources, acetate was the most useful in increasing sporulation and mosquito toxicity when added as a supplement to a nutrient broth-yeast extract-mineral salts medium. A glycerol supplement to this medium led to accumulation of acetic acid and suppression of sporulation and toxin formation. An acetate supplement and a mineral salts (Ca²⁺, Mg²⁺, Mn²⁺) supplement were found to increase sporulation in a fishmeal medium and thus may be useful for commercial production of mosquito larvicides from B. sphaericus. / M.S.

Ph. D.

Ethel M. Doidge's thesis is placed on the UIR in 2013 to celebrate 140 years of university education in South Africa. She was the first women to receive a D.Sc. from Unisa'a predecessor, the University of the Cape of Good Hope in 1914 / This thesis researched a mango disease which caused considerable loss to mango growers in South Africa at the beginning of the twentieth century, particularly around Barberton, Warm baths and the coastal region of Natal. The disease caused dark angular spots on the leaves. This did not noticeably affect the general health of the tree, but served as a source of infection for the fruit. The infected fruit is detached from the tree by the slightest air movement and falls rotting to the ground. The infection is carried by wind and rain. Several spraying experiments were carried out at Barberton in an orchard placed at the author's disposal by Messrs Winter Brothers during an exceptionally dry season, which showed that spraying with Bordeaux mixture, iron sulphide or Hyco/ was useless in checking the disease. The disease had not been described in the literature before. According to the author, the cause of the disease was a flagellate bacillus Bacillus mangiferae. It invades the parenchyma, wedging apart and killing the cells and causing gummosis, but it does not touch the lignified tissues. The organism is described, and was tested in detail in laboratory experiments and a resume of its salient characters is given in the thesis / Agriculture and  Animal Health / D.Sc. (Botany)

Thesis (MSc (Microbiology))--University of Stellenbosch, 2009. / Biomining organisms are generally found in metal-rich, inorganic environments such as iron and sulfur containing ores; where they play a vital role in mineralization and decomposition of minerals. They are typically obligatory acidophilic, mesophilic or thermophilic, autotrophic, usually aerobic, iron-or sulfur oxidizing chemolithotrophic bacteria. The most prominent biomining organisms used in bioleaching of metal sulfides are Acidithiobacillus ferrooxidans, At. thiooxidans, At. caldus, Sulfobacillus spp. and Leptospirillum spp. Biomining enables us to utilize low grade ores that would not have been utilized by conventional methods of mining. Research has focused on the backbone features of plasmids isolated from bacteria of biomining environments. The aim of this study is to sequence and analyze an 18 kb region of the 66 kb plasmid pTcM1 isolated from At. caldus MNG, focusing on accessory genes carried by this plasmid. Fifteen putative genes / open reading frames were identified with functions relating to metabolism and transport systems. The genes are located in two divergently located operons. The first operon carries features related to general metabolism activities and consists of a transcriptional regulator (ORF 2), a succinate / fumarate dehydrogenase-like subunit (ORF 3), two ferredoxin genes (ORF 4 and ORF 7), a putative HEAT-like repeat (ORF 6) which is interrupted by an insertion sequence (ORF 5) and a GOGAT-like subunit (ORF 8). The second operon contains an ABC-type nitrate / sulfonate bicarbonate-like gene (ORF 9), a binding protein-dependent inner membrane component-like gene, another ABC sulfonate / nitrate-like gene (ORF 12i and 12ii) which is interrupted by an insertion sequence (ORF 13) and two hypothetical proteins with unknown functions (ORF 14 and ORF 15). Southern hybridization analysis have shown that most of the genes from the two operons are found in other At caldus strains #6, “f”, C-SH12 and BC13 from different geographical locations. Expression of the GOGAT-like subunit and the succinate / fumarate-like subunit was demonstrated in At. caldus MNG showing that these genes are functional and actively transcribed. The transcriptional regulator (ORF 2) has been shown to repress the downstream genes of putative operon 1. The persistence of these genes on plasmids together with the fact that they are being expressed, represents a potential metabolic burden, which begs the question why they have been maintained on the plasmid from geographically separated strains (and perhaps also growing under very different nutrient availability conditions) and therefore what possible role they may play.

Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Cellulose, a ~-1,4-linked polymer of glucose, is the most abundant renewable carbon source on earth. It is well established that efficient degradation of cellulose requires the synergistic action of three categories of enzymes: endoglucanases (EG), cellobiohydrolases (CBH) and ~-glucosidases. ~-Glucosidases are a heterogenous group of enzymes that display broad substrate specificity with respect to hydrolysis of cellobiose and different aryl- and alkyl-ê-u-glucosides. They not only catalyse the final step in the saccharification of cellulose, but also stimulate the extent of cellulose hydrolysis by relieving the cellobiose mediated inhibition of EG and CBH. The ability to utilize cellobiose is widespread among gram-negative, gram-positive, and Archaea bacterial genera. Cellobiose phosphoenolpyruvate- dependent phosphotransferase systems (PTS) have been reported in various bacteria, including: Bacillus species. In this study, we have used a cellobiose chromophore analog, p-nitrophenyl- ~-D-glucopyranoside (pNPG), to screen a Bacillus pumilus genomic library for cellobiose utilization genes that are functionally expressed in Escherichia coli. Cloning and sequencing of the most active clone with subsequent sequence analysis allowed the identification of four adjacent open reading frames. An operon of four genes (celBACH), encoding a cellobiose phosphotransferase system (PTS): enzyme II (encoded by celB, celA and celC) and a ó-phospho-f-glucosidase (encoded by celH) was derived from the sequence data. The amino acid sequence of the celH gene displayed good homology with ~-glucosidases from Bacillus halodurans (74.2%), B. subtilis (72.7%) and Listeria monocytogenes (62.2%). .As implied by sequence alignments, the celH gene product belongs to family 1 of the glycosyl hydrolases, which employ a retaining mechanism of enzymatic bond hydrolysis. In vivo PTS activity assays concluded that the optimal temperature and pH at which the recombinant E. coli strain hydrolysed pNPG were pH 7.5 and 45°C, respectively. Unfortunately, at 45°C the CelBACH-associated activity of the recombinant strain was only stable for 20 minutes. It was also shown that the enzyme complex is very sensitive to glucose. Since active growing cells metabolise glucose very rapidly this feature is not a significant problem. Constitutive expression of the B. pumilus celBACH genes in E. coli enabled the host to efficiently metabolise cellobiose as a carbon source. However, cellobiose utilization was only achievable in the presence ofO.01% glucose. This phenomenon could be explained by the critical role of phosphoenolpyruvate (PEP) as the phosphate donor in PTS-mediated transport. Glucose supplementation induced the glycolytic pathway and subsequently the availability of PEP. Furthermore, it could be concluded that the general PTS components . (enzyme I and HPr) of E. coli must have complemented the CelBACH system from B. pumilus to allow functionality of the celBACH operon, in the recombinant E. coli host. / AFRIKAANSE OPSOMMING: Sellulose (' n polimeer van p-l,4-gekoppelde glukose) is die volopste bron van hernubare koostof in die natuur. Effektiewe afbraak van sellulose word deur die sinnergistiese werking van drie ensiernklasse bewerkstellig: endoglukanases (EG), sellobiohidrolases (CBH) en P-glukosidases. p-Glukosidases behoort tot 'n heterogene groep ensieme met 'n wye substraatspesifisiteit m.b.t. sellobiose en verskeie ariel- and alkiel-ê-n-glukosidiesc verbindings. Alhoewel hierdie ensieme primêr as kataliste vir die omskakeling van sellulose afbraak-produkte funksioneer, stimuleer hulle ook die mate waartoe sellulose hidroliese plaasvind deur eindprodukinhibisie van EG en CBH op te hef. Sellobiose word algemeen deur verskeie genera van die gram-negatiewe, gram-positiewe en Archae bakterieë gemetaboliseer. Die sellobiose-spesifieke fosfoenolpirovaatfosfotransportsisteem (PTS) is reeds is in verskeie bakterië, insluitende die Bacillus spesies, beskryf. In hierdie studie word die sifting van 'n Bacillus pumilus genoombiblioteek m.b.V. 'n chromofoor analoog van sellobiose, p-nitrofeniel-p-o-glukopiranosied (pNPG), vir die teenwoordigheid van gene wat moontlike sellobiose-benutting in Escherichia coli kan bewerkstellig, beskryf. Die DNA-volgorde van die mees aktiewe kloon is bepaal en daaropvolgende analiese van die DNA-volgorde het vier aangrensende oopleesrame geïdentifiseer. 'n Operon (celBACH), bestaande uit vier gene, wat onderskeidelik vir die ensiem II (gekodeer deur celB, celA en celC) en fosfo-B-glukosidase (gekodeer deur celH) van die sellobiose-spesifieke PTS van B. pumilus kodeer, is vanaf die DNA-volgorde afgelei. Die aminosuuropeenvolging van die celH-geen het goeie homologie met P-glukosidases van Bacillus halodurans (74.2%), B. subtilis (72.7%) en Listeria monocytogenes (62.2%) getoon. Belyning van die DNA-volgordes het aangedui dat die celH geenproduk saam met die familie 1 glikosielhidrolases gegroepeer kan word. Hierdie familie gebruik 'n hidrolitiese meganisme waartydens die stoigiometriese posisie van die anomeriese koolstof behou word. PTS-aktiwiteit van die rekombinante E. coli ras, wat die celBACH gene uitdruk, is in vivo bepaal. Die optimale temperatuur en pH waarby die rekombinante ras pNPG hidroliseer, is onderskeidelik pH 7.5 en 45°C. Alhoewel die ensiernkompleks baie sensitief is vir glukose, is dit nie 'n wesenlike probleem nie, omdat aktief groeiende E. coli selle glukose teen 'n baie vinnige tempo benut. Die celBACH operon het onder beheer van 'n konstitiewe promotor in E coli die rekombinante gasheer in staat gestelom sellobiose as 'n koolstofbron te benut. Die benutting van sellobiose word egter aan die teenwoordigheid van 'n lae konsentrasie glukose (0.01 %) gekoppel. Hierdie verskynsel dui op die kritiese rol van fosfoenolpirovaat (PEP) as die fosfaatdonor gedurende PTS-gebaseerde transport. Glukose speel waarskynlik 'n rol in die indusering van glikoliese, en sodoende die produksie van PEP as tussenproduk. Verder kan afgelei word dat die algemene PTS komponente (ensiem I en HPr) van E. coli die B. pumilis CelBACH-sisteem komplementeer en derhalwe funksionering van die celBACH operon in E. coli toelaat.

Ethel M. Doidge's thesis is placed on the UIR in 2013 to celebrate 140 years of university education in South Africa. She was the first women to receive a D.Sc. from Unisa'a predecessor, the University of the Cape of Good Hope in 1914 / This thesis researched a mango disease which caused considerable loss to mango growers in South Africa at the beginning of the twentieth century, particularly around Barberton, Warm baths and the coastal region of Natal. The disease caused dark angular spots on the leaves. This did not noticeably affect the general health of the tree, but served as a source of infection for the fruit. The infected fruit is detached from the tree by the slightest air movement and falls rotting to the ground. The infection is carried by wind and rain. Several spraying experiments were carried out at Barberton in an orchard placed at the author's disposal by Messrs Winter Brothers during an exceptionally dry season, which showed that spraying with Bordeaux mixture, iron sulphide or Hyco/ was useless in checking the disease. The disease had not been described in the literature before. According to the author, the cause of the disease was a flagellate bacillus Bacillus mangiferae. It invades the parenchyma, wedging apart and killing the cells and causing gummosis, but it does not touch the lignified tissues. The organism is described, and was tested in detail in laboratory experiments and a resume of its salient characters is given in the thesis / Agriculture and  Animal Health / D.Sc. (Botany)