An evaluation of a nutrient medium for isolating and cultivating Helicobacter pylori

Selective Helicobacter agar containing the selective supplement and blood, adding ex tempore, for the isolation and cultivation of H. pylori was developed. The Helicobacter agar was studied with the use of 5 newly isolated H. pylori strains, 13 bacterial associated cultures, as well as 21 inoculated biopsy specimens of the gastric and duodenal mucosa of patients with peptic ulcer. The study revealed that Helicobacter agar ensured the growth of H. pylori and their isolation from clinical material. The positive results after the inoculation of the specimens of biopsy material on Helicobacter agar and control media was 85%. In addition, the study of Helicobacter agar showed that it also exhibited pronounced selective properties with respect to bacterial associations, not inhibiting the growth of Helicobacter organisms and retaining their main biological properties. It is possible to recommend Helicobacter agar for use in laboratory practice in diagnosing Helicobacter-associated diseases.     

Isolation of Paenibacillus sp. and Variovorax sp. strains from decaying woods and characterization of their potential for cellulose deconstruction

Prospection of cellulose-degrading bacteria in natural environments allows the identification of novel cellulases and hemicellulases that could be useful in second-generation bioethanol production. In this work, cellulolytic bacteria were isolated from decaying native forest soils by enrichment on cellulose as sole carbon source. There was a predominance of Gram positive isolates that belonged to the phyla Proteobacteria and Firmicutes. Many primary isolates with cellulolytic activity were not pure cultures. From these consortia, isolation of pure constituents was attempted in order to test the hypothesis whether microbial consortia are needed for full degradation of complex substrates. Two isolates, CB1-2-A-5 and VG-4-A-2, were obtained as the pure constituents of CB1-2 and VG-4 consortia, respectively. Based on 16S RNA sequence, they could be classified as Variovorax paradoxus and Paenibacillus alvei. Noteworthy, only VG-4 consortium showed measurable xylan degrading capacity and signs of filter paper degradation. However, no xylan or filter paper degrading capacities were observed for the pure cultures isolated from it, suggesting that other members of this consortium were necessary for these hydrolyzing activities. Our results indicated that Paenibacillus sp. and Variovorax sp. as well as VG-4 consortium, might be a useful source of hydrolytic enzymes. Moreover, although Variovorax sp. had been previously identified in metagenomic studies of cellulolytic communities, this is the first report on the isolation and characterization of this microorganism as a cellulolytic genus.     

Cellulose-Enriched Microbial Communities from Leaf-Cutter Ant (Atta colombica) Refuse Dumps Vary in Taxonomic Composition and Degradation Ability

Deconstruction of the cellulose in plant cell walls is critical for carbon flow through ecosystems and for the production of sustainable cellulosic biofuels. Our understanding of cellulose deconstruction is largely limited to the study of microbes in isolation, but in nature, this process is driven by microbes within complex communities. In Neotropical forests, microbes in leaf-cutter ant refuse dumps are important for carbon turnover. These dumps consist of decaying plant material and a diverse bacterial community, as shown here by electron microscopy. To study the portion of the community capable of cellulose degradation, we performed enrichments on cellulose using material from five Atta colombica refuse dumps. The ability of enriched communities to degrade cellulose varied significantly across refuse dumps. 16S rRNA gene amplicon sequencing of enriched samples identified that the community structure correlated with refuse dump and with degradation ability. Overall, samples were dominated by Bacteroidetes, Gammaproteobacteria, and Betaproteobacteria. Half of abundant operational taxonomic units (OTUs) across samples were classified within genera containing known cellulose degraders, including Acidovorax, the most abundant OTU detected across samples, which was positively correlated with cellulolytic ability. A representative Acidovorax strain was isolated, but did not grow on cellulose alone. Phenotypic and compositional analyses of enrichment cultures, such as those presented here, help link community composition with cellulolytic ability and provide insight into the complexity of community-based cellulose degradation.     

Dysoxylum binectariferum bark as a new source of anticancer drug camptothecin: Bioactivity-guided isolation and LCMS-based quantification

Camptothecin (CPT, 1) is a potent anticancer natural product which led to the discovery of two clinically used anticancer drugs topotecan and irinotecan. These two drugs are semisynthetic analogs of CPT, and thus the commercial production of CPT as a raw material from various plant sources and tissue culture methods is highly demanding. In the present study, the Dysoxylum binectariferum bark, was identified as an alternative source of CPT, through bioassay-guided isolation. The barks showed presence of CPT (1) and its 9-methoxy analog 2, whereas CPT alkaloids were not present in seeds and leaves. This is the first report on isolation of CPT alkaloids from Meliaceae family. An efficient chromatography-free protocol for enrichment and isolation of CPT from D. binectariferum has been established, which was able to enrich CPT up to 21% in the crude extract. The LCMS (MRM)-based quantification method revealed the presence of 0.105% of CPT in dry barks of D. binectariferum. The discovery of CPT from D. binectariferum bark will certainly create a global interest in cultivation of this plant as a new crop for commercial production of CPT. Isolation of anticancer drug CPT from this plant, indicates that along with rohitukine, CPT and 9-methoxy CPT also contributes significantly to the cytotoxicity of D. binectariferum.     

The phylogenetic and ecological context of cultured and whole genome-sequenced planktonic bacteria from the coastal NW Mediterranean Sea

Microbial isolates are useful models for physiological and ecological studies and can also be used to reassemble genomes from metagenomic analyses. However, the phylogenetic diversity that can be found among cultured marine bacteria may vary significantly depending on the isolation. Therefore, this study describes a set of 136 bacterial isolates obtained by traditional isolation techniques from the Blanes Bay Microbial Observatory, of which seven strains have had the whole genome sequenced. The complete set was compared to a series of environmental sequences obtained by culture-independent techniques (60 DGGE sequences and 303 clone library sequences) previously obtained by molecular methods. In this way, each isolate was placed in both its “ecological” (time of year, nutrient limitation, chlorophyll and temperature values) context or setting, and its “phylogenetic” landscape (i.e. similar organisms that were found by culture-independent techniques, when they were relevant, and when they appeared). Nearly all isolates belonged to the Gammaproteobacteria, Alphaproteobacteria, or the Bacteroidetes (70, 40 and 20 isolates, respectively). Rarefaction analyses showed similar diversity patterns for sequences from isolates and molecular approaches, except for Alphaproteobacteria where cultivation retrieved a higher diversity per unit effort. Approximately 30% of the environmental clones and isolates formed microdiversity clusters constrained at 99% 16S rRNA gene sequence identity, but the pattern was different in Bacteroidetes (less microdiversity) than in the other main groups. Seventeen cases (12.5%) of nearly complete (98–100%) rRNA sequence identity between isolates and environmental sequences were found: nine in the Alphaproteobacteria, five in the Gammaproteobacteria, and three in the Bacteroidetes, indicating that cultivation could be used to obtain at least some organisms representative of the various taxa detected by molecular methods. Collectively, these results illustrated the largely unexplored potential of culturing on standard media for complementing the study of microbial diversity by culture-independent techniques and for obtaining phylogenetically distinct model organisms from natural seawater.     

A simple strategy for investigating the diversity and hydrocarbon degradation abilities of cultivable bacteria from contaminated soil

The use of indigenous bacterial strains is a valuable bioremediation strategy for cleaning the environment from hydrocarbon pollutants. The isolation and selection of hydrocarbon-degrading bacteria is therefore crucial for obtaining the most promising strains for site decontamination. Two different media, a minimal medium supplemented with a mixture of polycyclic aromatic hydrocarbons and a MS medium supplemented with triphenyltetrazolium chloride, were used for the isolation of bacterial strains from two hydrocarbon contaminated soils and from their enrichment phases. The hydrocarbon degradation abilities of these bacterial isolates were easily and rapidly assessed using the 2,6-dichlorophenol indophenol assay. The diversity of the bacterial communities isolated from these two soil samples and from their enrichment phases was evaluated by the combination of a bacterial clustering method, fluorescence ITS-PCR, and bacterial identification by 16S rRNA sequencing. Different PCR-based assays were performed in order to detect the genes responsible for hydrocarbon degradation. The best hydrocarbon-degrading bacteria, including Arthrobacter sp., Enterobacter sp., Sphingomonas sp., Pseudomonas koreensis, Pseudomonas putida and Pseudomonas plecoglossicida, were isolated directly from the soil samples on minimal medium. The nahAc gene was detected only in 13 Gram-negative isolates and the sequences of nahAc-like genes were obtained from Enterobacter, Stenotrophomonas, Pseudomonas brenneri, Pseudomonas entomophila and P. koreensis strains. The combination of isolation on minimal medium with the 2,6-dichlorophenol indophenol assay was effective in selecting different hydrocarbon-degrading strains from 353 isolates.     

Improved Method for Detection of Vibrio parahaemolyticus in Seafood

We have developed a new, effective procedure for detecting Vibrio parahaemolyticus in seafoods using enrichment and plating onto a chromogenic agar medium. Samples were cultured in salt Trypticase soy broth, which is a nonselective medium, and then a portion of the culture was cultured with salt polymyxin broth, which is a selective medium for V. parahaemolyticus. This two-step enrichment was more effective than the one-step enrichment in salt polymyxin broth alone. The enrichment cultures were then plated onto a new chromogenic agar containing substrates for beta-galactosidase. The V. parahaemolyticus colonies developed a purple color on this growth medium that distinguished them from other related bacterial strains. V. parahaemolyticus was isolated more frequently from naturally contaminated seafood samples using the chromogenic agar than thiosulfate citrate bile salts sucrose agar medium, which is currently used for the isolation of V. parahaemolyticus. Our findings suggest that this new enrichment and isolation scheme is more sensitive and accurate for identifying V. parahaemolyticus in seafood samples than previously used methods.     

Fungi Growing on Jute Fabrics Deteriorating under Weather Exposure and in Storage

Special media suitable for the isolation of fungi growing on jute were developed. Species that would better resist sunlight, such as organisms with dark hyphae and spores or closed fruit bodies, predominated on weather-exposed fabrics. Several strongly cellulolytic organisms not previously implicated in fiber decomposition were isolated from this source. On the other hand, the fungi obtained from jute materials damaged in storage were mostly of the familiar types. Most of the newly isolated fungi are generally missed on ordinary media, but they probably play an important role in the natural decomposition of jute materials.     

Disclosing a crypt: Microbial diversity and degradation activity of the microflora isolated from funeral clothes of Cardinal Peter Pázmány

A crypt can be considered as a particular environment where different microbial communities contribute to decomposition of organic materials present inside during a long interval of time. The textile remains of the funeral clothes (biretta and tunic) of Cardinal Pázmány, an important historic figure dead in Bratislava the 19th March 1637, conserved in this kind of environment were subjected to microbial investigation. The sampling comprised three different approaches and the use of various kinds of cultivation media. Two different PCR-based clustering methods, f-ITS and f-CBH, were employed in order to select the bacterial and fungal microfloras which were identified in a second step by the 16S rRNA and ITS sequencing respectively. The isolated microflora was tested for its proteolytic, keratinolytic and cellulolytic activities and for its ability to grow on Fibroin agar medium. The combination of cultural, molecular and biodegradative assays was able to isolate and characterize a bacterial community composed mainly by members of the phyla Firmicutes and Actinobacteria. The fungal community appeared more diversified, together with several Penicillium and Aspergillus strains, members belonging to the species Beauveria bassiana, Eurotium cristatum, Xenochalara juniperi, Phialosimplex caninus and Myriodontium keratinophilum were isolated. Bacteria, especially the Bacillus members, showed their strong ability to degrade keratin and gelatin and a large portion of them was able to growth on Fibroin agar. The fungal isolates displayed a widespread cellulolytic activity and fibroin utilization, although they possessed a weaker and slower proteolytic and keratinolytic properties respect to bacterial counterpart. The present study can be considered perhaps as the first or among the few microbial investigations which treated the textile biodegradation from such unusual environment.     

Detection of representatives of the Planctomycetes in Sphagnum peat bogs by molecular and cultivation approaches

By means of fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes (FISH), it has been shown that members of the phylum Planctomycetes represent a numerically significant bacterial group in boreal Sphagnum peat bogs. The population size of planctomycetes in oxic layers of the peat bog profile was in the range of 0.4–2.0 × 10⁷ cells per g of wet peat, comprising 4 to 13% of the total bacterial cell number. A novel effective approach that combined a traditional cultivation technique with FISH-mediated monitoring of the target organism during the isolation procedure has been developed for the isolation of planctomycetes. Using this approach, we succeeded in isolating several peat-inhabiting planctomycetes in a pure culture. Sequencing of the 16S rRNA genes from two of these isolates, strains A10 and MPL7, showed that they belonged to the planctomycete lineages defined by the genera Gemmata and Planctomyces, respectively. The 16S rRNA gene sequence similarity between strains A10 and MPL7 and the phylogenetically closest organisms, namely, Gemmata obscuriglobus and Planctomyces limnophilus, was only 90%. These results suggest that the indigenous planctomycetes inhabiting Sphagnum peat bogs are so far unknown organisms.     

Mesophilic aerobic Gram negative cellulose degrading bacteria from aquatic habitats and soils

New procedures have been developed for the isolation and purification of aerobic and facultatively anaerobic bacteria able to utilize cellulose as sole source of carbon and energy. Wood pulp medium was used for enrichment, and bacterial cellulose, obtained from cultures of Acetobacter aceti subsp. xylinus , was employed as carbon substrate during purification and for the rapid screening of colonies for cellulolytic activity. The methods have revealed several new groups of Gram negative cellulose-degrading bacteria, including organisms that form differentiated colonies superficially similar to myxobacterial sori. The organisms formed several phenetic clusters, three of which contained reference strains of Cellvibrio fulvus, Pseudomonas fluorescens var. cellulosa and Cytophaga hutchinsonii . No cellulose degrading cluster included non-cellulose degrading strains. Most of the cellulose degraders studied were flagellated and, of these, the majority had polar or lophotrichous flagella, although one cluster included peritrichously flagellated organisms. The cellulose degraders in this study included five organisms that grew on nitrate-free medium; these appeared in two different clusters. A few Gram positive isolates appeared to belong to the genera Streptomyces and Thermoactinomyces .     

Evaluation of Recovery Methods to Detect Coliforms in Water

Various recovery methods used to detect coliforms in water were evaluated by applying the membrane filter chamber technique. The membrane filter chambers, containing pure-culture suspensions of Escherichia coli or natural suspensions of raw sewage, were immersed in the stream environment. Samples were withdrawn from the chamber at regular time intervals and enumerated by several detection methods. In general, multiple-tube fermentation techniques gave better recovery than plating or membrane filtration procedures. The least efficient method of recovery resulted when using membrane filtration procedures, especially as the exposure period of the organisms to the stream environment increased. A 2-h enrichment on a rich, nonselective medium before exposure to selective media improved the recovery of fecal coliforms with membrane filtration techniques. Substantially enhanced recoveries of E. coli from pure-culture suspensions and of fecal coliforms from raw-sewage suspensions were observed when compared with recoveries obtained by direct primary exposure to selective media. Such an enrichment period appears to provide a nontoxic environment for the gradual adjustment and repair of injured cells.     

Comparison of Several Selective Media for Isolation and Differentiation of Coagulase-Positive Strains of Staphylococcus aureus

Six coagulase-positive strains of Staphylococcus aureus which had been cultivated in Brain Heart Infusion broth, milk, and brine were plated on seven isolation media. A significant difference in the growth patterns of the individual strains was found as well as a significant effect resulting from the previous cultivation history before plating. Brine and, to a lesser extent, milk were found to reduce maximal cell concentrations attained, but strains grown in brine and milk showed greater ability to withstand the selective action of the isolation media. Fibrinogen applied to the surface of five of the media allowed the formation of characteristic halos by coagulase-positive strains of S. aureus. Only half of the strains studied produced a zone of precipitation on SM110-Egg Yolk agar. The isolation medium containing cycloheximide and a high level of polymxin B was most inhibitory to the organisms.     

Degradation of furazolidone by bacteria Acinetobacter calcoaceticus T32, Pseudomonas putida SP1 and Proteus mirabilis V7

Furazolidone (FZD) has been widely used as an antibacterial and antiprotozoal feed additive for poultry, cattle and farmed fish. Since FZD has been shown to have mutagenic, genotoxic and potentially carcinogenic properties when tested in a variety of systems, there is an increasing need to find a way to remove FZD from contaminated environments. In this report, three bacterial strains Acinetobacter calcoaceticus T32, Pseudomonas putida SP1 and Proteus mirabilis V7 capable of degrading FZD effectively were isolated, identified and characterized. The reduced FZD concentration after degradation was determined by HPLC. After bacterial cells were grown in the media containing 5 mg l⁻¹ FZD for 5 days, almost all FZD was degraded by A. calcoaceticus T32, and more than 50% of FZD was degraded by P. putida SP1 and P. mirabilis V7, respectively. Bacterial GST activity of A. calcoaceticus T32, P. putida SP1 and P. mirabilis V7 was determined to be influenced by different FZD concentrations. Cytotoxicity analysis showed that FZD was degraded to the metabolites with far less cytotoxicity compared to FZD. The inoculation of bacterial strains A. calcoaceticus T32, P. putida SP1 and P. mirabilis V7 into FZD-contained media resulted in a higher degradation efficiency than natural degradation, which indicated the potential application of these strains in treatment of FZD-polluted freshwater or seawater environments.     

Enrichment of previously uncultured bacteria from natural complex communities by adhesion to solid surfaces

The adhesion to inert solid surfaces was explored as a novel approach for the enrichment of previously uncultured bacteria from natural microbial communities. Enrichments on solid steel, glass and synthetic polymeric surfaces were established using samples from five freshwater lakes, a marine microbial mat and an alpine soil, and were subsequently analysed by molecular fingerprinting and sequencing of their 16S rRNA gene fragments. The majority of the enriched phylotypes grouped with the Alphaproteobacteria, Betaproteobacteria or Bacteroidetes and in several cases were related to typical biofilm‐forming species and genera. Most enrichments were most closely related to previously uncultured phylotypes and none had previously been cultivated from the original environments even when applying improved high throughput liquid cultivation techniques. Of the 13 phylotypes enriched from freshwater samples, seven were previously unknown, three matched so‐far uncultured environmental clones, and three were identical to previously cultivated bacteria. Of the 17 phylotypes recovered from soil, 12 were previously unknown with five of these phylotypes representing novel genera, whereas five phylotypes were identical to previously cultured soil bacteria. The feasibility of the biofilm‐enrichment approach was exemplified by the successful isolation of a not‐yet cultured Betaproteobacterium that constituted a discernible component of the alpine soil microbial community in situ and exhibited only 93% similarity to its closest cultured relative. Based on these results, cultivation on solid surfaces represents a promising approach to recover isolates that have so far escaped cultivation as suspended cultures in liquid media.     

Diversity of Bacteria and Glycosyl Hydrolase Family 48 Genes in Cellulolytic Consortia Enriched from Thermophilic Biocompost

The enrichment from nature of novel microbial communities with high cellulolytic activity is useful in the identification of novel organisms and novel functions that enhance the fundamental understanding of microbial cellulose degradation. In this work we identify predominant organisms in three cellulolytic enrichment cultures with thermophilic compost as an inoculum. Community structure based on 16S rRNA gene clone libraries featured extensive representation of clostridia from cluster III, with minor representation of clostridial clusters I and XIV and a novel Lutispora species cluster. Our studies reveal different levels of 16S rRNA gene diversity, ranging from 3 to 18 operational taxonomic units (OTUs), as well as variability in community membership across the three enrichment cultures. By comparison, glycosyl hydrolase family 48 (GHF48) diversity analyses revealed a narrower breadth of novel clostridial genes associated with cultured and uncultured cellulose degraders. The novel GHF48 genes identified in this study were related to the novel clostridia Clostridium straminisolvens and Clostridium clariflavum, with one cluster sharing as little as 73% sequence similarity with the closest known relative. In all, 14 new GHF48 gene sequences were added to the known diversity of 35 genes from cultured species.The exploration and understanding of cellulose fermentation capabilities in nature could inform and enable industrial processes converting cellulosic biomass to fuels and other products. Enrichment of microbial communities that can utilize cellulose is useful in this context for the identification of novel organisms, novel metabolisms, and novel functions. Of particular interest are communities that can utilize cellulose at high temperatures and under anaerobic conditions, featuring high rates of solubilization under conditions where the energy and the reducing power of substrates are conserved in potentially useful fermentation products.Some evidence indicates that cocultures may be able to utilize cellulose more fully and produce higher concentrations of ethanol than pure cultures of model cellulolytic organisms such as Clostridium thermocellum and Clostridium straminisolvens (16, 20, 34). An initial step toward understanding the functional roles of community members in cooperative cellulose degradation is answering the question of what organisms are present in cellulolytic consortia obtained from nature. Currently, diversity estimation methods applied to cellulolytic communities range from traditional methods targeting the 16S rRNA gene (4, 12) to complex metagenomic analyses targeting the breadth of functional genes present in genomes of mixed cultures and the environment (3).From a functional gene standpoint, cellulase systems are complex assemblages of multifunctional glycosyl hydrolases. Even particularly relevant families, such as family 5 and family 9, tend to include hydrolases with multiple substrate specificities, deep evolutionary roots, and extensive sequence diversity within the same organism (19). However, family 48 glycosyl hydrolases include a select group of cellulosomal and unbound cellulases thought to play an essential role in cellulose solubilization by model cellulolytic clostridia (5, 7, 15), actinobacteria (6, 13), and anaerobic fungi (31). One key feature of this family of glycosyl hydrolases (mostly exoglucanases) is their ability to enhance cellulose solubilization in synergistic interactions with family 9 glycosyl hydrolases (2, 13). But unlike the latter, and with the notable exception of CelS and CelY in Clostridium thermocellum, family 48 hydrolases are present mostly in single copies in the genomes of cellulolytic microbes, making family 48 hydrolase genes a desirable target for primer design and molecular characterization.In this paper we describe the enrichment of microbial communities from a thermophilic compost pile and provide an assessment of diversity in stable cellulolytic enrichments by addressing total bacterial diversity using the 16S rRNA gene as well as introducing a novel method to assess functional diversity in cellulolytic consortia by targeting glycosyl hydrolase family 48 (GHF48) genes.     

In Vitro Culture of Previously Uncultured Oral Bacterial Phylotypes

Around a third of oral bacteria cannot be grown using conventional bacteriological culture media. Community profiling targeting 16S rRNA and shotgun metagenomics methods have proved valuable in revealing the complexity of the oral bacterial community. Studies investigating the role of oral bacteria in health and disease require phenotypic characterizations that are possible only with live cultures. The aim of this study was to develop novel culture media and use an in vitro biofilm model to culture previously uncultured oral bacteria. Subgingival plaque samples collected from subjects with periodontitis were cultured on complex mucin-containing agar plates supplemented with proteose peptone (PPA), beef extract (BEA), or Gelysate (GA) as well as on fastidious anaerobe agar plus 5% horse blood (FAA). In vitro biofilms inoculated with the subgingival plaque samples and proteose peptone broth (PPB) as the growth medium were established using the Calgary biofilm device. Specific PCR primers were designed and validated for the previously uncultivated oral taxa Bacteroidetes bacteria HOT 365 and HOT 281, Lachnospiraceae bacteria HOT 100 and HOT 500, and Clostridiales bacterium HOT 093. All agar media were able to support the growth of 10 reference strains of oral bacteria. One previously uncultivated phylotype, Actinomyces sp. HOT 525, was cultivated on FAA. Of 93 previously uncultivated phylotypes found in the inocula, 26 were detected in in vitro-cultivated biofilms. Lachnospiraceae bacterium HOT 500 was successfully cultured from biofilm material harvested from PPA plates in coculture with Parvimonas micra or Veillonella dispar/parvula after colony hybridization-directed enrichment. The establishment of in vitro biofilms from oral inocula enables the cultivation of previously uncultured oral bacteria and provides source material for isolation in coculture.     

Development of media to accelerate the isolation of indigo-reducing bacteria,which are difficult to isolate using conventional media

Indigo-reducing bacteria perform natural fermentation in indigo fermentation fluid. Owing to the stochastic nature of the process, the constituent in indigo fermentation fluid differ depending on the prepared batch and fermentation period. To identify new indigo-reducing bacteria, isolation of the bacteria is indispensable. However, isolation of indigo-reducing bacteria is difficult because conventional media are often unsuitable to isolate these slow-growing bacteria that also exist in low numbers. Hydrolysates of polysaccharides and mixtures of plant base constituents are candidates to accelerate the isolation of indigo-reducing bacteria that cannot be isolated using conventional media. In this current study, wheat bran hydrolysate and composted indigo leaves (sukumo) were used as ingredients in the fermentation fluid in the selective medium for indigo-reducing bacteria in anaerobic culture. The results suggested that obligate and oxygen-non-metabolizing facultative anaerobes are difficult to isolate using conventional media, whereas oxygen-metabolizing facultative anaerobes, relatively rapid-growing and major bacterial strains are relatively easy to isolate. Media containing sukumo hydrolysate facilitated the isolation of novel species of Bacillus pseudofirmus-related strains, whereas media containing wheat bran hydrolysate facilitated the isolation of Amphibacillus spp. (including new species). Seven species (including two new species) of indigo-reducing bacteria were isolated using wheat bran hydrolysate-containing media, whereas six species (including three new species) of indigo-reducing bacteria were isolated using media containing both wheat bran and sukumo hydrolysates. These newly developed culture media will facilitate the isolation of unknown bacteria in indigo fermentation and in environments similar to indigo fermentation fluid.     

Characterization of Isolates of Bacterial Blight of Cotton (Xanthomonas campestris pv. malvacearum) from Nicaragua

Seeds from cotton plants infected with Xanthomonas campestris pv. malvacearum were collected in different parts of Nicaragua in 1986. When the seeds were homogenized the pathogen could not always be identified by dilution plating. Therefore, an enrichment of bacteria on the natural host was induced before isolation. The cotton seeds were shaken with water and sand for 2 days and then sown in sand for germination. Rather often the developing cotyledons showed typical water-soaked spots, from which the pathogen could be isolated easily. This new method needed more time but made it possible to detect a low level of bacterial infestation. Altogether, 42 bacterial isolates were obtained. For inoculation experiments suspensions with 5x10⁵ CFU - ml^?1 were infiltrated into cotton leaves. Incubations of inoculated plants in growth chambers, but not in greenhouses, resulted in typical and uniform disease symptoms (water-soaked leaf spots). Nine of the ten cotton differentials tested were highly susceptible to all the 42 bacterial isolates. Since only line 101-102B proved to be resistant, the Nicaraguan isolates of bacterial blight of cotton were characterized as race 18, of the pathogen. The main cotton cultivars grown in Nicaragua (H-373 and G-286) were strongly affected by the isolated bacterial strains. In order to reduce the disease incidence in Nicaragua, the cultivation of resistant cotton varieties is suggested.     

Anaerobic cellulolytic bacteria from wetwood of living trees

Obligately anaerobic, mesophilic, cellulolytic bacteria were isolated from the wetwood of elm and maple trees. The isolation of these bacteria involved inoculation of selective enrichment cultures with increment cores taken from trees showing evidence of wetwood. Cellulolytic bacteria were present in the cores from seven of nine trees sampled, as indicated by the disappearance of cellulose from enrichment cultures. With two exceptions, cellulolytic activity was confined to the darker, wetter, inner section of the cores. Cellulolytic bacteria were also present in the fluid from core holes. The cellulolytic isolates were motile rods that stained gram negative. Endospores were formed by some strains. The physiology of one of the cellulolytic isolates (strain JW2) was studied in detail. Strain JW2 fermented cellobiose, d-glucose, glycerol, l-arabinose, d-xylose, and xylan in addition to cellulose. In a defined medium, p-aminobenzoic acid and biotin were the only exogenous growth factors required by strain JW2 for the fermentation of cellobiose or cellulose. Acetate and ethanol were the major nongaseous end products of cellulose fermentation. The guanine-plus-cytosine content of the DNA of strain JW2 was 33.7 mol%. Cellulolytic bacteria have not previously been reported to occur in wetwood. The isolation of such bacteria indicates that cellulolytic bacteria are inhabitants of wetwood environments and suggests that they may be involved in wetwood development.