Identification and population dynamics of bacteria in symptomatic oat leaves

Bacteria isolated from symptomatic oat leaves included pseudomonads,Erwinia herbicola, and others.Pseudomonas coronafaciens was isolated predominantly from leaves with halo blight symptoms or necrotic spots. Leaves with red leaf symptoms yielded many types of bacteria, including saprophytic pseudomonads,P. syringae, E. herbicola, Bacillus sp.,Micrococcus sp.,Corynebacterium sp., a yeast, and other unidentified species. Only isolates ofP. coronafaciens were pathogenic on the plant hosts tested. The bacteria associated with red leaf symptoms exist as saprophytes and/or epiphytes on leaves with those symptoms. It is concluded that bacteria do not contribute to red leaf symptom development in oats, but symptomatic leaves provide an environment for their growth.     

Antagonistic Activities of Epiphytic Bacteria from Soybean Leaves against Pseudomonas syringae pv. glycinea in vitro and in planta

Abstract Over two growing seasons, 273 bacterial strains were isolated from soybean leaves without and with bacterial blight symptoms caused by Pseudomonas syringae pv. glycinea (Psg). The majority of the isolates from leaves with symptoms were identified as Psg (43%), followed by Erwinia herbicola (21%), and Enterobacter/Erwinia (19%). The isolates from leaves without symptoms included mainly a group of unidentified Gram-negative bacteria (22%), Psg (21%), and E. herbicola (18%). Psg colonized the soybean leaves prior to saprophytic bacteria, and remained dominant during both seasons on healthy, as well as infected, leaves. Eighty-two saprophytic isolates were tested in vitro for their antagonistic activities against Psg, using an agar-diffusion assay. For the in planta assay, Psg and each isolate were simultaneously inoculated into wounds of pin-pricked leaves of greenhouse-grown soybean plants. Twenty-nine isolates were antagonistic in vitro. Nineteen isolates were able to suppress the growth of Psg and prevented the formation of leaf spots in planta when mixtures of isolate and pathogen were inoculated at ratios >1. Only 9 of the 82 isolates inhibited Psg in vitro as well as in planta. Most antagonists detected belonged to the genera Pseudomonas and the species Erwinia herbicola. The in planta assay should be a reliable predictor of field performance for screening of biological control agents. Received: 8 April 1996; Accepted: 22 October 1996     

Composition of the microflora of witloof chicory seeds

The bacterial microflora of nine varieties of witloof chicory (Cichorium intybus L. var.foliosum Hegi) seeds was studied. The 184 isolates were characterized by protein profiles determined by SDS-protein polyacrylamide gel electrophoresis of the total cell proteins. Isolates with identical protein profiles were grouped into one fingerprint type. Sixty-seven fingerprint types were distinguished. Two quantitatively major fingerprint types,Erwinia herbicola and an arthrobacter, represented 52% of the total number of isolates and were found on different chicory varieties. The latter organism was inhibited at seed germination. Other isolates, i.e.,Xanthomonas maltophilia, Pseudomonas paucimobilis, Agrobacterium radiobacter, Pseudomonas syringae, and a fluorescentPseudomonas, were only occasionally found. A minority were gram-positive isolates, i.e.,Bacillus sp.,Streptomyces sp., and coryneforms. In vitro activity of the isolates was tested against five fungi. Isolates with strong antifungal activity were found amongErwinia herbicola andBacillus sp.     

Appearance of a Host Protein in Cucumber Plants Infected with Viruses, Bacteria and Fungi

Electrophoretic analyses of extracts of cucumber leaves infectedwith Colleiotrichum lagenarium, Fusarium oxysporum f. sp. cucumerinum,Pseudomonas lachrymans, Erwinia tracheiphila, tobacco necrosisvirus or cucumber mosaic virus revealed the presence of a proteinband with an R_F value of 0.55–0.60 (based on mobilityof bromophenol blue) on 10% polyacrylamide gel. This band wasnot evident in extracts of healthy or mechanically wounded leaves.The protein was not detected in uninfected leaves of infectedplants, but it was detected in similar amounts in infected leavesand in secondarily challenged leaves of infected plants eventhough symptoms were not apparent on the latter. The proteinhad a molecular weight of approximately 16 000 d, was adsorbedon DEAE-cellulose, did not react with Schiff's reagent, anddid not have ribonuclease activity. When injected into cucumberleaves, it did not inhibit germination of conidia of C. lagenariumor induce resistance against disease caused by the fungus.     

A Multiphasic Approach for the Identification of Endophytic Bacterial in Strawberry Fruit and their Potential for Plant Growth Promotion

This study used a multiphasic approach, characterized by the simultaneous use of culture-dependent and culture-independent methods, to investigate endophytic bacterial communities in strawberry (Fragaria ananassa) fruit. A total of 92 bacterial endophytes were isolated and initially grouped by their repetitive extragenic palindromic (rep)-PCR banding pattern and biochemical features. Phylogenetic analysis of the 16S rRNA gene sequences of 45 representatives showed that the isolates belonged to the species Bacillus subtilis (eight isolates), Bacillus sp. (seven isolates), Enterobacter sp. (seven isolates), Enterobacter ludwigii (six isolates), Lactobacillus plantarum (six isolates), Pseudomonas sp. (five isolates), Pantoea punctata (three isolates), and Curtobacterium citreum (three isolates). Nucleic acids were extracted from the strawberry fruit and subjected to 16S rRNA gene directed polymerase chain reaction denaturing gradient gel electrophoresis (16S rRNA PCR-DGGE). The species B. subtilis, Enterobacter sp., and Pseudomonas sp. were detected both by isolation and DGGE. The DGGE fingerprints of total bacterial DNA did not exhibit bands corresponding to several of the representative species isolated in the extinction dilution (L. plantarum, C. citreum, and P. punctata). In contrast, bands in the DGGE profile that were identified as relatives of Arthrobacter sp. and one uncultivable Erythrobacter sp. were not recovered by cultivation techniques. After isolation, the nitrogen fixation ability and the in vitro production of indole-3-acetic acid (IAA) equivalents and siderophores were evaluated. A high percentage of isolates were found to possess the ability to produce siderophores and IAA equivalents; however, only a few isolates belonging to the genera Pseudomonas and Enterobacter showed the ability to fix nitrogen. Plant growth promotion was evaluated under greenhouse conditions and revealed the ability of the Bacillus strains to enhance the number of leaves, shoot length, root dry weight, and shoot dry weight. The activity of the bacterial isolate identified as B. subtilis NA-108 exerted the greatest influence on strawberry growth and showed a 42.8% increase in number of leaves, 15.26% for high shoot, 43.5% increase in root dry weight, and a 77% increase in shoot dry weight when compared with untreated controls.     

Diversity and phylogeny of bacteria on Zimbabwe tobacco leaves estimated by 16S rRNA sequence analysis

Microorganisms play important roles in the tobacco aging process. However, microbial communities on flue-cured tobacco leaves (FCTL) remain largely unknown. In this study, the total microbial genomic DNA of unaged and aging FCTL from Zimbabwe were isolated using a culture-independent method, and the bacterial communities were investigated through analyzing two 16S rRNA gene libraries. Eighty-four and 65 operational taxonomic units were obtained from the libraries of the unaged and aging FCTL, respectively. The following genera were represented more than 4% in both libraries (aging and unaged library): Sphingomonas (4.84%, 4.18%), Stenotrophomonas (4.84%, 5.23%), Erwinia (5.81%, 4.88%), Pantoea (19.35%, 18.47%), and Pseudomonas (21.29%, 24.04%). The dominant species varied between the two libraries. Specifically, several dominant species in unaged FCTL including Pseudomonas fulva, Pseudomonas sp. (AM909658), Klebsiella sp. (HM584796), and Pantoea sp. (AY501386) were not identified in aging FCTL, while several dominant species in aging FCTL such as Pantoea sp. (GU566350), Pseudomonas sp. (EF157292), and Buttiauxella izardii were not found in unaged FCTL. The phylogenetic analysis showed that bacteria from unaged and aging FCTL were divided into two clades, and two unique subclades were identified in aging FCTL. Our results revealed for the first time the bacterial diversities on Zimbabwe tobacco, and provided a basis for clarifying the roles of bacteria in aging process of FCTL.     

Bacterial soft rot of tomato in plastic greenhouses in Crete

During recent years a new disease has been noticed on tomatoes grown in Polythene greenhouses in Crete. Early symptoms are yellowing of the lower leaves, and a yellow brown discoloration of the pith and stem xylem. As leaves wilt and die there is progressive yellowing towards the top of the plants. A progressive disintegration of the cortical tissues follows which results in a soft rot and a longitudinal splitting of the stem running mainly upwards. Soft rot of the fruits rarely appears. Severely infected plants may wilt and die, but other less affected plants often survive and yield normally. Very vigorous plants grown under humid conditions are more susceptible. Often more than 20% of the plants are infected. Isolations were made from stem (xylem, cortex and pith), from leaf xylem and from fruits of infected tomato plants collected throughout the island from 1979 to 1985. Bacteria of the genus Erwinia and Pseudomonas were consistently isolated. On the basis of physiological and biochemical characters of 49 representative pathogenic isolates, 22 were identified as Erwinia carotovora subsp. carotovora, 10 as Erwinia carotovora subsp. atroseptica, four as Pseudomonas viridiflava and 13 as Pseudomonas fluorescens biotype I. All disease symptoms were reproduced when artificial inoculations were made with the above isolates in the laboratory (20°C and 100% r.h.) on 3–4 week tomato plants and in a commercial greenhouse on 4–5 months tomato plants. Bacteria used for inoculations were reisolated. Results indicated that the disease symptoms as described may be caused by four different bacteria species.     

Diversity and decomposition potential of endophytes in leaves of a Cinnamomum camphora plantation in China

This study was carried out to improve our understanding of the diversity and decomposition potential of endophytes in the leaves of Cinnamomum camphora trees grown in a subtropical region of China. We isolated and identified endophytic fungi from senescent leaves of C. camphora and tested their role in decomposition through pure-culture and pre-colonization. A total of 2,861 endophytic fungi isolated from 69 leaves of C. camphora were grouped into 39 taxa comprising 36 Ascomycetes and 3 Basidiomycetes based on sporulation and ITS sequence analysis. Of these, Colletotrichum gloeosporioides was the most common species (69% relative abundance and 96% colonization frequency), followed by Cladosporium sp.1, Colletotrichum sp. and Chaetomium sp. All 39 endophytes had the ability to decompose C. camphora leaf litter in pure culture, and a few exhibited >20% litter mass loss in 2 months. In most cases, single endopyhytic species showed lower mass loss than mixed microbial groups from active soil after 60 or 120 days. In pre-inoculation, endophytic fungi like Chaetomium sp., Cladosporium sp.1, C. gloeosporioides, Colletotrichum sp. and Guignardia sp. exhibited higher abundance and caused greater mass loss, indicating the potential of these groups to enter and significantly accelerate the process of decomposition. This study concludes that, after entering the decomposition process, selected endophytic fungi with high abundance could influence significantly the decomposition process and thus probably affect carbon and nutrient cycling in C. camphora plantations.     

Potentially pathogenic and biocontrol Ascomycota associated with green wall structures of basket willow (<Emphasis Type="Italic">Salix viminalis</Emphasis> L.) revealed by phenotypic characters and ITS phylogeny

Ascomycota are among the fungi that cause serious willow diseases in all natural habitats worldwide. This study was conducted to determine if basket willow used in green wall structures (GWS) built of willow stems were infected by potentially important fungal diseases or their antagonists in urban areas of eastern Canada. In total, 13 different phenotypic genera belonging to eight families of ascomycetous fungi were isolated and identified according to their sexual and/or asexual forms. Venturia pathogenic species complex were represented by three different anamorphs: Fusicladium, Fusicladium-Cladosporium, and Pollaccia as anamorph. They were responsible for the highest incidence value on leaves (IF > 15%). Cryptodiaporthe, Drepanopeziza, and Glomerella dominated on bark (IF > 5%). A significantly higher incidence value of fungal communities was found on first year than on second year GWS. The correspondence analysis using χ² distance showed that communities of potentially pathogenic species are closely related to diseased plants, while healthy plants often contain biocontrol species such as Cladobotryum mycoparasite on healthy bark and Alternaria sp. antagonist on healthy leaves. The phylogenetic positions of the different fungal taxa and their relationship have been revealed by use of PCR amplified internal transcriber spacer (ITS) region of rDNA.     

Ecology and impact of Allorhogas sp. (Hymenoptera: Braconidae) and Apion sp. (Coleoptera: Curculionoidea) on fruits of Miconia calvescens DC (Melastomataceae) in Brazil

Two fruit-feeding insects, a gall wasp, Allorhogas sp. (Hymenoptera: Braconidae), and a beetle, Apion sp. (Coleoptera: Curculionoidea), were evaluated in their native habitat in Brazil as potential biological control agents of Miconia calvescens DC (Melastomataceae). Allorhogas sp. occurred at two out of three field sites with native populations of M. calvescens, and Apion sp. occurred at all three sites. Both species exhibited aggregated distributions among M. calvescens trees sampled at each site. Allorhogas sp. infested 9.0% and 3.8% of fruits at each of two sites. The number of larvae and pupae of Allorhogas sp. and/or an unidentified parasitoid (Hymenopetera: Eulophidae: Tetrastichinae) ranged from one to five per infested fruit. Fruits infested with Allorhogas sp. were 20% larger and had 79% fewer seeds than healthy fruits. Although adults of Apion sp. were found on leaves and inflorescences of M. calvescens at all three sites, larvae and pupae were found in fruits at only one site, where a maximum of 1.4% of fruits were infested. Fruits infested by Apion sp. contained only one larva or pupa, and were 15% smaller and had 62% fewer seeds than healthy fruits. While a variety of apionids have been used for biological control in the past, this is the first time a braconid wasp has been considered for biological control of a weed.     

What is more important for invertebrate colonization in a stream with low-quality litter inputs: exposure time or leaf species?

The objective of this study was to evaluate the influences of detritus from the leaves of different species, and of exposure time on invertebrate colonization of leaves in a shaded Cerrado stream. We hypothesized that the exposure time is the main factor that influences the colonization of leaves by invertebrates. We used leaves of five tree species native to the Brazilian Cerrado: Protium heptaphyllum and Protium brasiliense (Burseraceae), Ocotea sp. (Lauraceae), Myrcia guyanensis (Myrtaceae), and Miconia chartacea (Melastomataceae), which are characterized by their toughness and low-nutritional quality. Litter bags, each containing leaves from one species, were placed in a headwater stream and removed after 7, 15, 30, 60, 90, and 120 days. The dominant taxon was Chironomidae, which comprised ca. 52% of all organisms and ca. 20% of the total biomass. The taxonomic richness of colonizing organisms did not vary among the leaf species. However, the density and biomass of the associated organisms varied differently among the kinds of detritus during the course of the incubation. The collector-gatherers and shredders reached higher densities in the detritus that decomposed more rapidly (Ocotea sp. and M. guyanensis), principally in the more advanced stages of colonization. The collector-filterers reached higher densities in the detritus that decomposed more slowly (P. heptaphyllum, P. brasiliense, and M. chartacea), principally in the initial stages of incubation. A cluster analysis divided the detritus samples of different leaf species according to the exposure time (initial phase: up to 7 days; intermediate phase: 7–30 days; advanced phase: 30–120 days), suggesting some succession in invertebrate colonization, with differences in taxon composition (indicator taxa analysis). These results suggest that regardless of the leaf-detritus species, exposure time was the main factor that influenced the colonization process of aquatic invertebrates.     

The Ways of Plant Colonization by MethylobacteriumStrains and Properties of These Bacteria

The pink-pigmented facultative methylotrophic bacteria (PPFMB) of the genus Methylobacteriumare indispensible inhabitants of the plant phyllosphere. Using maize Zea maysas a model, the ways of plant colonization by PPFMB and some properties of the latter that might be beneficial to plants were studied. A marked strain, Methylobacterium mesophilicumAPR-8 (pULB113), was generated to facilitate the detection of the methylotrophic bacteria inoculated into the soil or applied to the maize leaves. Colonization of maize leaves by M. mesophilicumAPR-8 (pULB113) occurred only after the bacteria were applied onto the leaf surface. In this case, the number of PPFMB cells on inoculated leaves increased with plant growth. During seed germination, no colonization of maize leaves with M. mesophilicumcells occurred immediately from the soil inoculated with the marked strain. Thus, under natural conditions, colonization of plant leaves with PPFMB seems to occur via soil particle transfer to the leaves by air. PPFMB monocultures were not antagonistic to phytopathogenic bacteria. However, mixed cultures of epiphytic bacteria containing Methylobacterium mesophilicumor M. extorquensdid exhibit an antagonistic effect against the phytopathogenic bacteria studied (Xanthomonas campestris, Pseudomonas syringae, Erwinia carotovora, Clavibacter michiganense,andAgrobacterium tumifaciens). Neither epiphytic nor soil strains of Methylobacterium extorquens, M. organophillum, M. mesophilicum, andM. fujisawaensecatalyzed ice nucleation. Hence, they cause no frost injury to plants. Thus, the results indicate that the strains of the genus Methylobacteriumcan protect plants against adverse environmental factors.     

Heat-Killed Lactic Acid Bacteria Inhibit Nitric Oxide Production via Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in RAW 264.7 Cells

Heat-killed lactic acid bacteria perform immunomodulatory functions and are advantageous as probiotics, considering their long product shelf-life, easy storage, and convenient transportation. In this study, we aimed to develop appropriate heat treatments for industrial preparation of probiotics with antioxidant activity. Among 75 heat-killed strains, Lactococcus lactis MG5125 revealed the highest nitric oxide inhibition (86.2%), followed by Lactobacillus acidophilus MG4559 (86.0%), Lactobacillus plantarum MG5270 (85.7%), Lactobacillus fermentum MG4510 (85.3%), L. plantarum MG5239 (83.9%), L. plantarum MG5289 (83.2%), and L. plantarum MG5203 (81.8%). Moreover, the heat-killed selected strains markedly inhibited lipopolysaccharide-induced nitric oxide synthase and cyclooxygenase-2 expression. The use of heat-killed bacteria with intact bio-functionality can elongate the shelf-life and simplify the food processing steps of probiotic foods, given their high stability. The antioxidant and immune-modulatory activities of the heat-killed strains selected in this study indicate a strong potential for their utilization probiotic products manufacturing.

     

Selective herbivory by brushtail possums: Determining the age of ingested leaves using n‐alkanes

Abstract Leaves often decline in nutritional quality as they age, and selective feeding on young leaves may be nutritionally important for herbivores. Preference by mammalian herbivores for young leaves has rarely been measured in the field owing to technical difficulties. We measured preferences with respect to leaf age of an arboreal folivore, the brushtail possum (Trichosurus vulpecula Kerr), feeding on southern rata (Metrosideros umbellata Cav.; Myrtaceae) in a new application of the alkane technique. We characterized the cuticle waxes (n‐alkanes) of rata leaves that were less than 1 year old (‘1‐year’), between 1 and 2 years (‘2‐year’) and greater than 2 years old (‘>2‐year’). Simulations showed that the method accurately discriminated between 1‐year and other age groups but slightly overestimated the importance of rare components of the diet. This bias was larger when discriminating between 2‐year and >2‐year leaves apparently because they had more‐similar alkane profiles. Metrosideros umbellata leaf formed 20.8% of the diet of a population of possums from Rakiura, New Zealand, sampled in autumn 2002 (n = 33). Of the M. umbellata component, alkane analyses showed that 1‐year leaves formed 88.7 ± 3.9% of the diet despite making up only 39.5 ± 2.2% of the leaf biomass on rata trees (n = 14). The foliar concentrations of the macronutrients N, P and K all declined significantly with leaf age (P < 0.0001). Lignin content did not measurably increase with leaf age, suggesting that digestibility per se did not determine the preference of brushtail possums for young rata leaves. This study provides the first quantitative evidence that possums discriminate by leaf age and that the resulting diet is enriched in macronutrients.     

Effect of three antagonists on the development of bacterial leaf streak of rice

Among 11 epiphytic microorganisms one species each of Pseudomonas, Erwinia, and Aspergillus were antagonistic to Xanthomonas translucens subsp. oryzicola. Symptoms of bacterial leaf streak did not develop when the antagonists were sprayed on rice leaves 24 h before inoculation. Although the symptoms developed when the antagonists were applied 24 h after inoculation, the number of lesions and their length was significantly reduced over control. When the mixture of each antagonist and the pathogen was applied, no symptoms developed with Pseudomonas and Aspergillus sp. However, the symptoms could develop with Erwinia sp. although the number and length of the lesions was reduced over control.     

The Potentiality of Free Gram-negative Bacteria for Removing Oil and Grease from Contaminated Industrial Effluents

Summary Eight bacterial species were isolated from vegetable oil and grease-contaminated industrial wastewater, only four of which were found to have the ability to degrade oil and grease in the contaminated wastewater. These isolates were identified according to morphological and biochemical profiles as, Pseudomonas sp. (L1), P. diminuta (L2), P. pseudoalcaligenes (L3), and Escherichia sp. (L5). The degradative capabilities of the identified bacterial isolates for Tween 20 (Tw20) were investigated under different pH levels (6.5, 7, 7.5, and 8), different temperatures (30 and 37 °C) and different concentrations of Tw20 (1, 1.5, and 2%). Results revealed differences in their optimum conditions for maximum degradation of vegetable oil. Bacterial isolates were tested individually or in combinations using synthetic aqueous medium supplemented with 1% palm oil, incubated at 30 °C, and agitated at 150 rev/min for 13 days. All the tested bacteria were able to degrade the palm oil completely and utilized the free fatty acids (FFA) as a carbon source. The combination M1 (Pseudomonas sp. and P. diminuta) produced the highest degradative activity, followed by M3 (Pseudomonas sp., P. diminuta and P. pseudoalcaligenes). Also M1 produced the highest activity in reducing COD (93%) and BOD₅ (100%).     

Endophytic Actinomycetes from <Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss.: Isolation,Diversity, and Anti-microbial Activity

Endophytic actinomycetes from Azadirachta indica A. Juss. were screened and evaluated for their anti-microbial activity against an array of pathogenic fungi and bacteria. A total of 55 separate isolates were obtained from 20 plants, and 60% of these showed inhibitory activity against one or more pathogenic fungi and bacteria. Actinomycetes were most commonly recovered from roots (54.5% of all isolates), followed by stems (23.6%), and leaves (21.8%). The dominant genus was Streptomyces (49.09% of all isolates), while Streptosporangium (14.5%), Microbispora (10.9%), Streptoverticillium (5.5%), Sacchromonospora sp. (5.5%), and Nocardia (3.6%) were also recovered. Streptomyces isolates AzR 006, 011, and 031 (all from roots) had acute activity against Pseudomonas fluorescens, while AzR027, 032, and 051 (also all from roots) showed activity against Escherichia coli. Meanwhile, an isolate of Nocardia sp. from leaves (AzL025) showed antagonism against Bacillus subtilis. Overall, 32 of the 55 were found to have broad spectrum significant antimicrobial activity, while about 4% of them showed strong and acute inhibition to pathogenic fungi and bacteria. Isolates of Streptomyces AzR031, 008, and 047, Nocardia sp. AzL025, and Streptosporangium sp. AzR 021 and 048 are of particular interest because they showed significant antagonistic activity against root pathogens, including Pythium and Phytophthora sp. Thus, many of the isolates recovered from A. indica in this study may be used in developing potential bio-control agents against a range of pathogenic fungi and bacteria and in the production of novel natural antimicrobial compounds. These results not only further our understanding of plant–microbe interactions but also indicate that there is an untapped resource of endophytic microorganisms that could be exploited in the biotechnological, medicinal, and agricultural industries.     

Survival and Possible Spread of Erwinia amylovora and Related Plant-Pathogenic Bacteria Exposed to Environmental Stress Conditions

The fire blight pathogen Erwinia amylovora was assayed for survival under unfavourable conditions such as on nitrocellulose filters, in non‐host plants as well as in inoculated mature apples and in infested apple stem sections. In a sterile dry environment, an E. amylovora EPS (exopolysaccharide) mutant, and to a lesser extent its parental wild‐type strain decreased within 3 weeks to a low titre. However, under moist conditions the decrease of viable cells occurred only partially for both strains. Very low cell titres were recovered after application of E. amylovora onto the surface of tobacco leaves, whereas infiltration into the leaves produced lesions (hypersensitive response, HR), in which the bacteria survived in significant amounts. A similar effect was found for the necrotic zones of HR in tobacco leaves caused by E. pyrifoliae, by Pseudomonas syringae pathovars and HR‐deficient E. amylovora mutants or mutants deficient in EPS synthesis and disease‐specific genes. During 7 years of storage, the viability of E. amylovora in wood sections from fire blight‐infested apple trees declined to a low titre. In tissue of mature apples, E. amylovora cells slowly dispersed and could still be recovered after several weeks of storage at room temperature. A minimal risk of accidental dissemination of E. amylovora apart from infested host plants can experimentally not be excluded, but other data confirm a very low incidence of any long distance distribution.     

Antagonism of Lactic Acid Bacteria against Phytopathogenic Bacteria

A variety of lactic acid bacteria, isolated from plant surfaces and plant-associated products, were found to be antagonistic to test strains of the phytopathogens Xanthomonas campestris, Erwinia carotovora, and Pseudomonas syringae. Effective “in vitro” inhibition was found both on agar plates and in broth cultures. In pot trials, treatment of bean plants with a Lactobacillus plantarum strain before inoculation with P. syringae caused a significant reduction of the disease incidence.     

Microbial biodiversity and in situ bioremediation of endosulfan contaminated soil

Molecular characterization based on 16s rDNA gene sequence analysis of bacterial colonies isolated from endosulfan contaminated soil showed the presence of Ochrobacterum sp, Burkholderia sp, Pseudomonas alcaligenes, Pseudomonas sp and Arthrobacter sp which degraded 57–90% of α-endosulfan and 74–94% of β-endosulfan after 7days. Whole cells of Pseudomonas sp and Pseudomonas alcaligenes showed 94 and 89% uptake of α-isomer and 86 and 89% of β-endosulfan respectively in 120 min. In Pseudomonas sp, endosulfan sulfate was the major metabolite detected during the degradation of α-isomer, with minor amount of endosulfan diol while in Pseudomonas alcaligenes endosulfan diol was the only product during α-endosulfan degradation. Whole cells of Pseudomonas sp also utilized 83% of endosulfan sulfate in 120 min. In situ applications of the defined consortium consisting of Pseudomonas alcaligenes and Pseudomonas sp (1:1) in plots contaminated with endosulfan showed that 80% of α-endosulfan and 65% of β-endosulfan was degraded after 12 weeks of incubation. Endosulfan sulfate formed during endosulfan degradation was subsequently degraded to unknown metabolites. ERIC-PCR analysis indicated 80% survival of introduced population of Pseudomonas alcaligenes and Pseudomonas sp in treated plots.