Enterobacter Agglomerans Strain Research Articles

Evaluation of the heteroantagonism between Enterobacter agglomerans strains isolated from vulture (Coragyps atratus) for production and Pseudomonas aeruginosa as developed

The heteroantagonism between Enterobacter agglomerans, isolated from the gastrointestinal tract of American vulture Coragyps atratus, and Pseudomonas aeruginosa isolated from a hospital environment was evaluated. The slow (layer) and the wells (direct) techniques were tested, using agar and soy tryptone broth pH 7.3 at 37ºC. Through the slow method from 196 tests, inhibition growth halos, related heteroantagonism phenomenon observed in 118, corresponding to 60.2% positive results. Equivalent positive results were detected using wells (direct) methodology. The seven samples of E. agglomerans tested were capable of revealing heteroantagonism in the experimental conditions; antagonism reveled by the presence of a clear growth inhibition halo. The added 1% yeast extract to media was adequate for revealing antagonisms best.

First Report of Boll Rot of Cotton Caused by Pantoea agglomerans in China.

Since the summer of 2006, bacterial boll rot of cotton has been observed on fruits of 'Xinluzao 31' (Xinluzao 6 × Acala) in Xinjiang Province. It resulted in as much as 20% yield loss in several fields. Symptoms do not appear on the outer carpel. In the infected cotton bolls, fibers do not mature completely and seed tissue exhibits brown necrotic coloration. Lint and seeds from 24 surface-disinfested cotton bolls were triturated and plated onto King's medium B (KB). Plates were incubated at 28°C for 48 h. Forty eight strains with yellow pigmentation on KB were characterized. All were nonfluorescent on KB, gram negative, facultatively anaerobic, unable to produce indole from tryptophan, able to reduce nitrate to nitrite, and produce acid from glucose, cellobiose, lactose, melibiose, and melonate. In addition, 16S rDNA in seven strains was amplified with universal primers (1). The PCR products were cloned into pGEM-T easy vector and sequenced. A BLAST search of the seven sequences against the GenBank nucleotide library indicated 100% identity with the 16S rDNA sequence of Enterobacter agglomerans strain A80. Then an additional primer pair, pagF and pagR (3), was used for more specific amplification of Pantoea agglomerans 16S rDNA, which resulted in single highly specific fragments of approximately 1 kb. On the basis of morphological, physiological, biochemical characteristics, and 16S rRNA gene sequence analysis, we identified the bacterium to be P. agglomerans. To confirm pathogenicity, cell suspensions (1 × 108 CFU/ml) of eight representative strains were used to inoculate cotton at peak bolling stage in the field. Cell suspensions, or water as the control, were applied to stigma scars, wall sutures, and scratch wounds on bracts, calyxes, and bolls. Alternatively, a needle was used to puncture through a drop of suspension placed on the boll wall suture and bracts. At least 20 bolls or flowers were inoculated with each bacterial strain per inoculation method. Infection occurred only when bacterial injections breached the endocarp of the boll either through the carpel wall or a suture between carpel sections. Disease symptoms developed 1 week postinoculation. The inoculated organism was reisolated from the diseased tissues. P. agglomerans is generally regarded to be a soil saprophyte or leaf epiphyte, but strains can opportunistically infect plants triggering gall formations or human wounds causing septic arthritis. The disease symptoms and pathogen characteristics observed in this study are identical to those reported in the United States (2). To our knowledge, this is the first report of P. agglomerans causing boll rot of cotton in China.

Isomerization of deoxyhexoses: green bioproduction of 1-deoxy- d-tagatose from l-fucose and of 6-deoxy- d-tagatose from d-fucose using Enterobacter agglomerans strain 221e

1-Deoxy- d-tagatose was produced by the hydrogenation of 6-deoxy- l-galactose ( l-fucose) to l-fucitol followed by oxidation with Enterobacter agglomerans 221e; a similar sequence on d-fucose afforded 6-deoxy- d-tagatose. Thus, the polylol dehydrogenase recognizes the d- galacto-configuration of both d-fucitol and l-fucitol. The procedures were conducted in water and show the power of green, environmentally friendly biotechnology in the preparation of new monosaccharides with a potential for novel bioactive properties. 6-Deoxy- d-tagatose was also synthesized from d-tagatose via the efficient formation of 1,2:3,4-di- O-isopropylidene-α- d-tagatofuranose; a difficult final removal of protecting groups by acid makes the biotechnological route more attractive.

Influence of food preservation parameters and associated microbiota on production rate, profile and stability of acylated homoserine lactones from food-derived Enterobacteriaceae

Quorum-dependent regulation is mediated by N-acyl- l-homoserine lactones (AHLs) in several Gram-negative bacteria. The production of AHLs has typically been studied using pure bacteria cultures grown in nutrient-rich media at optimal temperature. AHLs are produced in several chill-stored foods by Gram-negative bacteria participating in spoilage. As part of our investigation of the role of AHLs in food quality, we studied the AHL production in two Enterobacteriaceae isolated from cold-smoked salmon under growth conditions typical of those found in cold-smoked salmon. We tested the influence of carbon source (glucose, sucrose, xylose, arabinose, mannose, mannitol and sorbitol), temperature (5 and 25 °C), salt concentration (0–7%), pH (6, 7 and 8) and co-existing lactic acid bacteria microflora on the AHL profile and production rate from Serratia proteamaculans strain B5a and Enterobacter agglomerans strain B6a. The two strains produced the same types of AHLs under all conditions tested. The specific AHL concentrations (moles/liter/OD 450) changed slightly for both strains at the various conditions. S. proteamaculans strain B5a produced approximately 150 nM/OD 450 N-3-oxo-hexanoyl homoserine lactone (OHHL) and E. agglomerans strain B6a produced two major signals, OHHL and N-3-oxo-octanoyl homoserine lactone (OOHL) in a 1:9 ratio with a total concentration of approximately 3000 nM/OD 450. The AHL signal molecules became unstable with increasing pH (>7.5). In cold-smoked salmon, pH is approximately 6 and therefore only a low degree of pH-induced turnover is expected to occur in this product. Overall, our study demonstrates that food-derived Enterobacteriaceae produce AHLs of the same type and in the same magnitude when grown under food-relevant conditions as when grown in laboratory media at high temperature. Also, the AHLs produced in foods will be relatively stable and their regulatory impact lasting during storage.

Transformed bacterial symbionts re-introduced to and detected in host gut.

Strains of Enterobacter agglomerans and Klebsiella pneumoniae isolated from Rhagoletis completa Cresson were engineered to express transgenic fluorescent proteins (ECFP, DsRed). These bacteria were introduced into flies by feeding the flies a sucrose solution in which the bacteria were suspended. The transgenic and heterologous marker protein was expressed and visible in the bacteria after they were ingested by WHF and while they were in the fly gut. We describe the plasmids used to transform these bacteria and demonstrate expression of heterologous proteins from the transforming plasmids and discuss the implications for future pest control strategies.

Purine metabolizing capability of Enterobacter agglomerans affects volatiles production and attractiveness to Mexican fruit fly.

We investigated two strains of Enterobacter agglomerans that differ in their ability to metabolize uric acid for (1) attractiveness to sugar-fed Mexican fruit flies, and (2) production of volatile chemicals that may be responsible for the attractiveness. The two strains were cultured on a medium that contained uric acid as the primary nitrogen source to simulate bird feces, a natural substrate for this bacterium. Active cultures of both strains were more attractive than uninoculated uric acid medium to both sexes of sugar-fed flies in wind-tunnel bioassays. The uricase(+) strain was more attractive than the uricase(-) strain to males and to females <9 days old, but not to older females. Volatiles found by solid-phase microextraction in greater amounts in headspace above active cultures of both strains than above uninoculated medium were ammonia, dimethyldisulfide, 3-methylbutanol, 2-phenylethanol, 2,5-dimethylpyrazine, and trimethylpyrazine. The uricase(+) strain produced more ammonia, dimethyldisulfide, and trimethylpyrazine than the uricase(-) strain. An additional chemical, 3-hydroxybutanone, appears to be produced exclusively by the uricase(+) strain. The uricase(-) strain produced more 2-phenylethanol than the uricase(+) strain. Differences in volatiles are consistent with the generally greater attractiveness of the uricase(+) strain compared with the uricase(-) strain as ammonia, 3-hydroxybutanone, and trimethylpyrazine have been demonstrated attractive to sugar-fed Mexican fruit flies.

Preservation of chitinolytic Pantoae agglomerans in a viable form by cellular dried alginate-based carriers.

Improved viability of Gram-negative bacteria during freeze-dehydration, storage, and soil inoculation is of crucial importance to their efficient application. The chitinolytic Pantoae (Enterobacter) agglomerans strain IC1270, a potential biocontrol agent of soil-borne plant-pathogenic fungi, was used as a model organism to study the efficacy of freeze-dried alginate-based beads (macrocapsules) as possible carriers for immobilized Gram-negative bacterial cells. These macrocapsules were produced by freeze-dehydration of alginate gel spherical beads, in which different amounts of bacteria, glycerol, and colloidal chitin were entrapped. Subsequent drying produced different unexpected structures, pore-size distributions, and changes in the outer and inner appearance of the resultant dried cellular solid. With increasing glycerol content, the proportion of larger pores increased. These structures can be related to changes in the slow-release properties of the dried beads. The amount of glycerol in the beads differed from that in the alginate solution as a result of leakage during the beads' preparation and dehydration. Entrapping 10(9) cells per bead produced from alginate solution containing 30% glycerol and 1% chitin resulted in improved (in comparison to other studies) survival prospects (95%) during freeze-drying. Moreover, immobilization of the bacterium sharply improved its survival in nonsterile irrigated and dry soils compared to bacteria in a water suspension. The results suggest that optimized conservation of Gram-negative bacteria in dry glycerol-containing alginate-based cellular solids is not only possible but applicable for a variety of uses.

Development of Bacterial Resistance to the Third Generation Cephalosporins and Their Clinical Use

Development of Gram-negative rods resistance to the third generation cephalosporins (cefotaxime, ceftazidime, cefoperazone) in connection with their application at the University Hospital in Olomouc was evaluated in this study. The highest increase in resistance to cefotaxime was detected in Enterobacter cloacae (from 22.9% in 1995 to 49.0% in 1997) and Enterobacter agglomerans strains (28.0% - 40.5%). In addition, increased resistance to ceftazidime in Acinetobacter baumannii (12.5% - 35.1%), Enterobacter aerogenes (7.4% - 20.9%), Enterobacter cloacae (16.7% - 47.2%) and Pseudomonas aeruginosa (4.0% - 26.3%) was observed. Finally, the greatest increase in frequency of strains resistant to cefoperazone was observed in E. aerogenes (18.4% - 30.1%), E. agglomerans (31.0% - 52.3%), E. cloacae (35.5% - 47.2%) and Providencia rettgeri (26.5% - 53.2%).A 23.5% increase in third generation cephalosporin use was evident by evaluation of RDDDATB parameters in 1996 and 1997. Corresponding values for individual antibiotics were 26.5% cefotaxime, 20.7% ceftriaxone, and 40.3% ceftazidime increase. However, cefoperazone use decreased by 10.9%.

Bacteriophage and associated polysaccharide depolymerases--novel tools for study of bacterial biofilms.

Bacteriophage for three representative strains of Gram-negative biofilm bacteria have proved to be of widespread occurrence. Lytic bacteriophage have been isolated from local sewage for the bacterium 1.15, an exopolysaccharide (EPS)-producing pseudomonad found originally as a component of biofilms in a local river, and for two Enterobacter agglomerans strains from industrial biofilms. Representative examples of all three bacteriophage possess a relatively low burst size and on solid media, exhibit very large plaques surrounded by a wide halo (5-20 mm) indicative of polysaccharide depolymerase action. The bacteriophage are thus similar to other viruses for EPS-producing bacteria in inducing the synthesis of enzymes degrading the polymers which occlude the bacterial cell surface. In each preparation, the polysaccharase activity was associated both with sedimented phage particles and with the supernate of bacterial lysates. The enzymes have been partially purified and used to prepare polysaccharide digests in which the major products from each polysaccharide are the presumed repeat units of the polymers or oligomers of these. The soluble phage enzymes each degrade their substrate by acting as endo-glycanohydrolases. The phage and their associated enzymes thus provide very useful highly specific tools for studies of biofilms incorporating the bacterial host strains. Their potential applications in studies on bacterial biofilms are discussed.

Attraction of Rhagoletis pomonella (Diptera: Tephritidae) Flies to Odor of Bacteria: Apparent Confinement to Specialized Members of Enterobacteriaceae

Dominant species of bacteria isolated from leaves and fruit of pesticide-free MacIntosh apple trees, and chicken and barn swallow feces, were tested for attractancy to apple maggot flies, Rhagoletis pomonella (Walsh). The flies demonstrated a distinct preference for odor emitted by certain members of the Enterobacteriaceae but not for odor emitted by certain members of the Streptococcaceae or Pseudomonadales. Both attractive and nonattractive strains of Enterobacter agglomerans were obtained, suggesting intraspecific variation in attractiveness.

The gene for indole-3-acetyl-L-aspartic acid hydrolase from Enterobacter agglomerans: molecular cloning, nucleotide sequence, and expression in Escherichia coli.

A 5.5-kb DNA fragment containing the indole-3-acetyl-aspartic acid (IAA-asp) hydrolase gene (iaaspH) was isolated from Enterobacter agglomerans strain GK12 using a hybridization probe based on the N-terminal amino acid sequence of the protein. The DNA sequence of a 2.4-kb region of this fragment was determined and revealed a 1311-nucleotide ORF large enough to encode the 45-kDa IAA-asp hydrolase. A 1.5-kb DNA fragment containing iaaspH was subcloned into the Escherichia coli expression plasmid pTTQ8 to yield plasmid pJCC2. Extracts of IPTG-induced E. coli cultures containing the pJCC2 recombinant plasmid showed IAA-asp hydrolase levels 5 to 10-fold higher than those in E. agglomerans extracts. Homology searches revealed that the IAA-asp hydrolase was similar to a variety of amidohydrolases. In addition, IAA-asp hydrolase showed 70% sequence identity to a putative thermostable carboxypeptidase of E. coli.

Inhibition of Salmonella typhimurium Attachment to Chicken Cecal Mucus by Intestinal Isolates of Enterobacteriaceae and Lactobacilli

The ability of selected strains of Enterobacteriaceae or lactobacilli isolated from the intestines of adult chickens to inhibit in vitro attachment of Salmonella typhimurium 3333/O to cecal mucus in the presence or absence of D-mannose was determined. Attachment in the absence of mannose was reduced by prior exposure of mucus to cultures of two isolates of Enterobacteriaceae, an Escherichia coli and a Hafnia alvei strain, but not to a third isolate, an Enterobacter agglomerans strain. Attachment of S. typhimurium was not inhibited when mannose was present in the blocking or attachment step. Formation of fimbriae by the two inhibitory Enterobacteriaceae strains and the S. typhimurium strain, as indicated by titers of mannose-sensitive hemagglutination of guinea pig erythrocytes was optimal in Z biphasic medium (consisting of tryptone, yeast extract, dextrose, and NaCl) incubated anaerobically at 42 C. Fimbriae of each of three strains prepared from these cultures also inhibited attachment. These are characteristics consistent with attachment and inhibition of attachment mediated by a mannose-sensitive adhesin associated with type 1 fimbriae on bacterial cells of Enterobacteriaceae strains. Attachment in the presence of mannose was significantly reduced by prior exposure of mucus to cultures of a Lactobacillus salivarius strain and a Lactobacillus delbrueckii delbrueckii strain but not to a strain of Lactobacillus for which the species had not been determined. Washed cells or spent culture supernatant fluid from brain-heart infusion broth, Z broth, or Z biphasic cultures of the inhibitory strains of lactobacilli incubated at 37 or 42 C inhibited this form of attachment. Of 27 intestinal isolates of Enterobacteriaceae and 21 of lactobacilli, the lactobacilli strains were generally more hydrophobic than the Enterobacteriaceae as determined by adherence to hexadecane. The lactobacilli isolates did not agglutinate guinea pig erythrocytes. The data suggest more than one mechanism for mediating attachment of inhibitory bacterial strains and for subsequent attachment of S. typhimurium.

Growth suppression in early-stationary-phase nutrient broth cultures of Salmonella typhimurium and Escherichia coli is genus specific and not regulated by sigma S.

We have studied the growth suppression seen in early-stationary-phase LB broth cultures of Salmonella typhimurium. Multiplication of small numbers of an antibiotic-resistant S. typhimurium mutant was prevented when the mutant was added to 24-h cultures of the antibiotic-sensitive parent strain, whereas an antibiotic-resistant mutant of an Escherichia coli strain added to the same culture grew well. A 24-h E. coli culture produced a similar specific bacteriostatic inhibition against E. coli. In older cultures, a specific bactericidal effect similar to that observed by M. M. Zambrano and R. Kolter (J. Bacteriol. 175:5642-5647, 1993) was also observed. Whether incubated statically or shaken, sufficient nutrients were present in the filtered supernatants of 24-h cultures for small inocula of the same strain to multiply to ca. 10(9) CFU/ml after reincubation. Introduction of the rpoS mutation had no effect on the specific bacteriostatic inhibition. Similar specific inhibition was also observed in strains of Citrobacter freundii, Klebsiella pneumoniae, Enterobacter agglomerans, and Shigella spp. Experiments in which the 24-h culture was physically separated from the antibiotic-resistant mutant by using a dialysis membrane were carried out. These results indicated that the inhibition might be mediated by a diffusible but labile chemical mediator.

Pyrrolnitrin Production by an Enterobacter agglomerans Strain with a Broad Spectrum of Antagonistic Activity Towards Fungal and Bacterial Phytopathogens

Strain IC1270 of Enterobacter agglomerans has been previously described as a producer of a complex of chitinolytic enzymes and as an antagonist of many fungal phytopathogens [Chernin et al. (1995) Appl. Env. Microbiol. 61:1720–1726]. Here we show that this strain also produces an antibiotic that was purified by TLC and HPLC and identified by UV, IR, MS, and NMR analyses as pyrrolnitrin [3-chloro-4-(2′-nitro-3′-chlorophenyl)pyrrole]. The purified antibiotic is efficient against many phytopathogenic bacteria and fungi in vitro. This is the first piece of evidence showing that pyrrolnitrin can be produced by bacteria other than Pseudomonas and that one bacterial strain can simultaneously produce chitinolytic enzymes and pyrrolnitrin. The possible role of a combination of chitinases and pyrrolnitrin in antagonism is discussed.

Potential Inoculum Sources for Decay of Fresh‐cut Celery

ABSTRACTBacteria responsible for decay of precut celery (Apium graveolens) appear to be residents on the plants at harvest. Bacterial genera isolated from equipment in a fresh celery packinghouse were similar to those found on plants sampled at the packinghouse entrance. Population densities and array of genera were highest on unwashed plants, whereas certain genera were no longer detected on the washed plants. Fluorescent Pseudomonas spp. predominated, but strains of Pantoea agglomerans (=Erwinia herbicola), Enterobacter agglomerans, Aeromonas, Arthrobacter, and Aureobacterium were frequently isolated. Members of the coliform group such as Citrobacter, Klebsiella, and Escherichia were rare.

Isolation of Ice-Nucleating Active Bacteria from the Freeze-Tolerant Frog, Rana sylvatica

Ice-nucleating active (INA) bacteria were isolated from the gut of field-collected freeze-tolerant wood frogs ( Rana sylvatica) collected in winter. Thirteen strains of Pseudomonas fluorescens, four strains of Pseudomonas putida , and two strains of Enterobacter agglomerans had ice-nucleating activity. Each of the INA pseudomonad strains was psychrophilic. P. putida strains were differentiated from P. fluorescens strains by gelatinase, lecithinase, and lipase production. The maximum nucleation temperatures (T max) of aqueous suspensions (10° bacteria/ml) of the four INA P. putida strains ranged from -1.6 to -3.0°C, which places this INA species among the most potent known biological nucleators. Ingestion of INA P. putida isolated from R. sylvatica by another freeze-tolerant frog, Pseudacris crucifer, decreased the capacity of this frog to supercool and remain unfrozen at -2°C. This is the first report of INA bacteria isolated from a vertebrate, and suggests that, as part of the gut flora in some posthibernation freeze-tolerant wood frogs, these bacteria may play a role in enhancing winter survival by promoting ice nucleation at high subzero temperatures (ca. -2°C).

Chitinolytic Enterobacter agglomerans Antagonistic to Fungal Plant Pathogens

Three Enterobacter agglomerans strains which produce and excrete proteins with chitinolytic activity were found while screening soil-borne bacteria antagonistic to fungal plant pathogens. The chitinolytic activity was induced when the strains were grown in the presence of colloidal chitin as the sole carbon source. It was quantitated by using assays with chromogenic p-nitrophenyl analogs of disaccharide, trisaccharide, and tetrasaccharide derivatives of N-acetylglucosamine. A set of three fluorescent substrates with a 4-methylumbelliferyl group linked by (beta)-1,4 linkage to N-acetylglucosamine mono- or oligosaccharides were used to identify the chitinolytic activities of proteins which had been renatured following their separation by electrophoresis. This study provides the most complete evidence for the presence of a complex of chitinolytic enzymes in Enterobacter strains. Four enzymes were detected: two N-acetyl-(beta)-d-glucosaminidases of 89 and 67 kDa, an endochitinase with an apparent molecular mass of 59 kDa, and a chitobiosidase of 50 kDa. The biocontrol ability of the chitinolytic strains was demonstrated under greenhouse conditions. The bacteria decreased the incidence of disease caused by Rhizoctonia solani in cotton by 64 to 86%. Two Tn5 mutants of one of the isolates, which were deficient in chitinolytic activity, were unable to protect plants against the disease.

Purification and characterization of a ribitol dehydrogenase from Enterobacter agglomerans strain 221e

Ribitol dehydrogenase (EC 1.1.1.56) of Enterobacter agglomerans strain 221e was purified to homogeneity by polyethylene glycol precipitation, anion exchange chromatography on diethylaminoethyl (DEAE)-Toyopearl 650 M, hydrophobic chromatography on Phenyl-Toyopearl 650 M and gel filtration on Sephadex G-150. The enzyme was specific for NAD + but showed a broad substrate specificity for various polyols. Among those tested ribitol exhibited the highest affinity for the enzyme followed by allitol, l-arabitol, l-mannitol, xylitol, l-sorbitol, l-talitol, l-iditol, d-sorbitol, galactitol and erythritol. The enzyme showed maximum activity at pH 9–10 and was stable in the pH range of 9–11. The native enzyme exhibited an isoelectric point of about 4.9 and was estimated to have an apparent M r of 92,000 as determined by Sephadex G-150 gel filtration. SDS-PAGE data suggested that ribitol dehydrogenase of strain 221e has a subunit M r of 25,000.

Conversion of d-psicose to allitol by Enterobacter agglomerans strain 221e

Enterobacter agglomerans strain 221e transformed d-psicose to allitol at a faster rate in the presence of d-glucose in the reaction mixture when the entrance of oxygen was restricted. Cells grown on glycerol were found to be suitable for the transformation reaction. The transformation rates were about 97.0, 95.0 and 62.5%, respectively, when 0.5, 1.0 and 2.0% substrates were used. No consumption of substrate or product was observed in any case. In flask and jar fermentor reactions, the cells of strain 221e showed similar transformation activities. Cells stored at −20°C for 10 d showed almost same transformation activity as intact cells.

Demonstration of the indolepyruvate decarboxylase gene homologue in different auxin-producing species of the Enterobacteriaceae.

Different Enterobacteriaceae were assayed for their ability to produce the plant hormone indole-3-acetate with the aim to study the distribution of the indole-3-pyruvate pathway, which is known to be involved in the production of indole-3-acetate in a root-associated Enterobacter cloacae strain. Other E. cloacae strains, and also Enterobacter agglomerans strains, Pantoea agglomerans, Klebsiella aerogenes, and Klebsiella oxytoca were found to convert tryptophan into indole-3-acetate. As it was also intended to identify the conserved regions of the indole-3-pyruvate decarboxylase, which is involved in producing indole-3-acetate in the E. cloacae strain, oligonucleotide primers were synthesized for different regions of the corresponding gene. One pair of these primers allowed us to amplify a segment of the predicted size by the polymerase chain reaction with DNA of the seven different Enterobacteriaceae that produce indole-3-acetate. Segments of five strains were cloned and sequenced. All sequences showed significant homology to the indole-3-pyruvate decarboxylase gene. As in addition a positive DNA-DNA hybridization signal was detected in the seven strains using the E. cloacae or E. agglomerans segments as a probe, indole-3-acetate biosynthesis is suggested to be catalyzed via the indole-3-pyruvate pathway not only in E. cloacae but also in the other soil-living Enterobacteriaceae. Conserved regions were detected in the indole-3-decarboxylase by alignment of the now-available five different partial sequences. These regions should enable identification of the gene in other bacterial families or even in plants.