Regulation of nitrogenase levels in Anabaena sp. ATCC 33047 and other filamentous cyanobacteria

Incubation in the dark of photoautotrophically grown N₂-fixing heterocystous cyanobacteria leads to a loss of nitrogenase activity. Original levels of nitrogenase activity are rapidly regained upon re-illumination of the filaments, in a process dependent on de novo protein synthesis. Ammonia, acting indirectly through some of its metabolic derivatives, inhibits the light-promoted development of nitrogenase activity in filaments of Anabaena sp. ATCC 33047 and several other cyanobacteria containing mature heterocysts. The ammonia-mediated control system is also operative in N₂-fixing filaments in the absence of any added source of combined nitrogen, with the ammonia resulting from N₂-fixation already partially inhibiting full expression of nitrogenase. High nitrogenase levels, about two-fold higher than those in normal N₂-fixing Anabaena sp. ATCC 33047, are found in cell suspensions which have been treated with the glutamine synthetase inhibitor l-methionine-d,l-sulfoximine or subjected to nitrogen starvation. Filaments treated in either way are insensitive to the ammonia-promoted inhibition of nitrogenase development, although this insensitivity is only transitory for the nitrogen-starved filaments, which become ammonia-sensitive once they regain their normal nitrogen status.Abbreviations Chl chlorophyll - EDTA ethylenediaminetetraacetic acid - MSX l-methionine-d,l-sulfoximine     

Short-term ammonium inhibition of nitrate utilization by Anacystis nidulans and other cyanobacteria

Ammonium at low concentrations caused a rapid and effective inhibition of nitrate utilization in the light by the cyanobacterium Anacystis nidulans without affecting the cellular level of nitrate reductase activity. The inhibition was reversible, and the ability of the cells to utilize nitrate was restored immediately after ammonium had been exhausted. The inhibitory effect was dependent on consumption by the cells of the added ammonium which was rapidly incorporated into amino acids. In the presence of L-methionine-d,l-sulfoximine (MSX) or azaserine, inhibitors of the glutamine synthetase-glutamate synthase pathway, ammonium did not exhibit any inhibitory effect on nitrate utilization. Ammonium assimilation, rather than ammonium itself, seems to regulate nitrate utilization in A. nidulans. Short-term inhibition by ammonium of nitrate utilization and its prevention by MSX were also demonstrated in the filamentous cyanobacteria Anabaena and Nostoc.Abbreviations MSX L-Methionine-d-l-sulfoximine     

Production and physicochemical characterization of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079

Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, a partial sequence of this peptide is determined, together with data on its secondary structure. A modification of the MRS-growth medium (replacing the detergent Tween 80 with oleic acid), was shown to improve the production level of the peptide by one order of magnitude, as well as to stabilize the activity level. Addition of a detergent (Tween 20, less interfering in mass spectrometric analysis), was however necessary for solubilization of the purified acidocin D20079. Digestion of the peptide followed by de-novo sequencing of generated fragments, allowed determination of a partial sequence consisting of 39 of the totally estimated 65 residues. Acidocin D20079 has a high content of glycine residues, hydrophobic residues, and acidic residues. No modified amino acids were found. Edman degradation, and C-terminal sequencing failed, suggesting that the peptide may be cyclic, and a novel member of class IIc bacteriocins. Circular dichroism spectroscopy and secondary structure prediction showed random coil conformation in aqueous solution, but secondary structure was induced in the presence of sodium-dodecyl sulfate. The data could be fitted assuming 2–13% of the residues to be in α-helix and 23–27% of the residues to be in β-strand conformation. This indicates that a membrane/membrane-mimicking hydrocarbon–water interface induces an active conformation.     

Ultrastructure of the nitrogen-fixing,filamentous, nonheterocystous cyanobacterium,Plectonema boryanum

Summary The ultrastructure of fructose-supplemented and unsupplemented nitrogen-fixing (fix +) and nonfixing (fix –)Plectonema boryanum UTEX 581 cells was examined by transmission electron microscopy. The most prominent structural differences included the arrangement and morphology of the thylakoids and alterations in the appearance of the interthylakoidal spaces. These ultrastructural differences, together with other observations such as glycogen content and presence of nitrogenase (using acetylene reduction assay and immunogold localization), readily distinguished nonfixingP. boryanum from nitrogen-fixing cells.     

Isolation and characterization of rapidly-growing,marine, nitrogen-fixing strains of blue-green algae

Five strains of heterocystous blue-green algae capable of high rates of growth and nitrogenase activity were isolated from shallow coastal environments. Growth of the organisms was characterized with respect to temperature, NaCl concentration in the medium, and nitrogen source. The temperature optima ranged from 35–42°C, and all but one of the strains displayed a requirement for added NaCl. The generation times under N₂-fixing conditions were 5.1–5.9 h, and were as low as 3.4 h for growth on NH₄Cl. Nitrogenase activity (C₂H₂ reduction) was high throughout the logarithmic growth phase of each strain. The maximum value observed for one strain was 65.5 nmoles C₂H₄ produced/mg protein x min, and the average values for the five strains ranged from 24.5–46.7 nmoles C₂H₄/mg protein x min. The organisms all belong to the genusAnabaena. The growth and nitrogenase activity of these strains are much higher than those of the heterocystous blue-green algae commonly used for investigation of nitrogen metabolism, and they thus should prove to be useful physiological tools. Their prevalence, as judged by the ease of their enrichment and isolation, in bay and estuarine environments suggests that they are important contributors of combined nitrogen.     

Sulphated exopolysaccharides produced by two unicellular strains of cyanobacteria,Synechocystis PCC 6803 and 6714

The exopolysaccharides (EPS) of two unicellular strains of cyanobacteria Synechocystis PCC 6803 and 6714, formed labile, radial structures, uniformly distributed on the cell surface, and stainable by specific dyes for acidic polysaccharides. The two strains produced EPS at similar rates, which depended, along with the duration of the producing phase, on the incubation conditions. The exopolysaccharides from both strains were constituted of at least 11–12 mono-oses, probably forming several types of polymers. They contained about 15–20% (w/w) uronic derivatives and 10–15% (w/w) osamines. Proteins represented 20–40% of total weight. A most interesting feature was the presence of 7–8% (molar ratio) sulphate residues, a characteristic that is otherwise limited to exopolysaccharides produced by eukaryotic algae.Abbreviations EPS exopolysaccharides - KDO 3-deoxy-d-mannooctulosonate - LPS lipopolysaccharides     

Effects of the inoculation of cyanobacteria on the microstructure and the structural stability of a tropical soil

Cyanobacteria are widespread photosynthetic microorganisms among which some are able to fix atmospheric nitrogen. We investigated the impact of indigenous cyanobacteria strains (Nostoc) inoculation on physical characteristics of poorly aggregated soils from Guquka (Eastern Cape, South Africa). The soil aggregates (3–5 mm) were arranged into a layer of 10–20 mm thick, and sprayed with cyanobacteria solution. Subsequently the inoculated and un-inoculated samples were incubated (30°C, 80% humidity, continuous illumination at 100 μmol m⁻² s⁻¹). Their micromorphological characteristics and aggregate stability were investigated, after 1, 2, 3, 4 and 6 weeks of incubation, by using high resolution Cryo-SEM and aggregate breakdown tests. Micromorphological investigations revealed that the surface of un-inoculated samples remained uncovered, while the inoculated samples were partially covered by cyanobacteria material after one week of incubation. A dense superficial network of cyanobacterial filaments and extracellular polymer secretions (EPS) covered their surface after 4 and 6 weeks of incubation. Organo-mineral aggregates comprising cyanobacterial filaments and EPS were observed after 6 weeks of incubation. The results of aggregate breakdown tests showed no significant difference between un-inoculated samples after 1, 2, 3, 4 or 6 weeks, while they revealed improvement of aggregate stability for inoculated samples. The improvement of aggregate stability appeared in a short while following inoculation and increased gradually with time and cyanobacteria growth. The increase in aggregate stability is likely related to the changes induced in micromorphological characteristics by cyanobacterial filaments and EPS. It reflects the effect of coating, enmeshment, binding and gluing of aggregates and isolated mineral particles by cyanobacteria material. Our study presents new data demonstrating the improvement of soil physical quality in a few weeks after cyanobacteria inoculation. The interaction of the inocula and other biotic components is worthy of study before field application of cyanobacteria.     

Purification and characterization of curvaticin L442, a bacteriocin produced by Lactobacillus curvatus L442

Lactobacillus curvatus L442, isolated from Greek traditional fermented sausage prepared without the addition of starters, produces a bacteriocin, curvaticin L442, which is active against the pathogen Listeria monocytogenes. The bacteriocin was purified by 50% ammonium sulphate precipitation, cation exchange, reverse phase and gel filtration chromatography. Partial N-terminal sequence analysis using Edman degradation revealed 30 amino acid residues, revealing high homology with the amino acid sequence of sakacin P. Curvaticin L442 is active at pH values between 4.0 and 9.0 and it retains activity even after incubation for 5 min at 121 °C with 1 atm of overpressure. Proteolytic enzymes and α-amylase inactivated this curvaticin, while the effect of lipase was not severe.     

Sucrose synthase is involved in the conversion of sucrose to polysaccharides in filamentous nitrogen-fixing cyanobacteria

Higher plants and cyanobacteria metabolize sucrose (Suc) by a similar set of enzymes. Suc synthase (SuS, UDP-glucose: D: -fructose 2-alpha-D: -glucosyl transferase, EC 2.4.1.13) catalyses the synthesis and cleavage of Suc, and in higher plants, it plays an important role in polysaccharides biosynthesis and carbon allocation. In this work, we have studied the functional relationship between SuS and the metabolism of polysaccharides in filamentous nitrogen-fixing cyanobacteria. We show that the nitrogen and carbon sources and light regulate the expression of the SuS encoding gene (susA), in a similar way that they regulate the accumulation of polysaccharides. Furthermore, glycogen content in an Anabaena sp. mutant strain with an insertion inactivation of susA was lower than in the wild type strain under diazotrophic conditions, while both glycogen and polysaccharides levels were higher in a mutant strain constitutively overexpressing susA. We also show that there are soluble and membrane-bound forms of SuS in Anabaena. Taken together, these results strongly suggest that SuS is involved in the Suc to polysaccharides conversion according to nutritional and environmental signals in filamentous nitrogen-fixing cyanobacteria.     

Preliminary studies of cyanobacteria, picoplankton, and virioplankton in the Salton Sea with special attention to phylogenetic diversity among eight strains of filamentous cyanobacteria

Cyanobacterial diversity in the Salton Sea, a high-salinity, eutrophic lake in Southern California, was investigated using a combination of molecular and morphological approaches. Representatives of a total of 10 described genera (Oscillatoria, Spirulina, Arthrospira, Geitlerinema, Lyngbya, Leptolyngbya, Calothrix, Rivularia, Synechococcus, Synechocystis) were identified in the samples; additionally, the morphology of two cultured strains do not conform to any genus recognized at present by the bacteriological system. Genetic analysis, based on partial 16S rRNA sequences suggested considerable cryptic genetic variability among filamentous strains of similar or identical morphology and showed members of the form-genus Geitlerinema to be distributed among three major phylogenetic clades of cyanobacteria. Cyanobacterial mats, previously described from the Sea were, in fact, composed of both filamentous cyanobacteria and a roughly equivalent biomass of the sulfur-oxidizing bacterium Beggiatoa, indicating their formation in sulfide rich regions of the lake. Flow cytometric analysis of the water samples showed three striking differences between samples from the Salton Sea and representative marine waters: (1) phycoerythrin-containing unicells, while abundant, were much less abundant in the Salton Sea than they were in typical continental shelf waters, (2) Prochlorococcus appears to be completely absent, and (3) small (3–5 m) eukaryotic algae were more abundant in the Salton Sea than in typical neritic waters by one-to-two orders-of-magnitude. Based on flow cytometric analysis, heterotrophic bacteria were more than an order of magnitude more abundant in the Salton Sea than in seawater collected from continental shelf environments. Virus particles were more abundant in the Salton Sea than in typical neritic waters, but did not show increases proportionate with the increase in bacteria, picocyanobacteria, or eukaryotic algae.     

Development of a biofertilizer based on filamentous nitrogen-fixing cyanobacteria for rice crops in Chile

The purpose of this study was to develop a biofertilizer based on filamentous nitrogen-fixing cyanobacteria selected from rice fields and to generate a technological package compatible with its use for the rice crop in Chile. Thirty-four Chilean rice fields, located between Maule and BioBío regions, were sampled during the 1998/1999 and 1999/2000 growing seasons. A total of 9 species and 3 varieties of cyanobacteria were found, and the nitrogen fixation rate under laboratory conditions was determined for 6 of them. Only 4 were used for the small-scale production of a biofertilizer, which was assayed in field trials. To check the efficiency of the biofertilizer during the rice crop, the nitrogen fixation rates in soil samples were estimated. Additionally, the biofertilizer application efficiency was tested in combination with nitrogen synthetic fertilizer, in rates that were previously established in field trials. Biofertilization allowed a decrease of up to 50% in the use of nitrogen synthetic fertilizer (50 kg N ha⁻¹), resulting in the same grain yield (7.4 t ha⁻¹) and quality in relation to the fertilized control. The use of biofertilizers based on local strains of cyanobacteria shows promise to increase nitrogen use efficiency in rice.     

Functional response of Anodonta anatina feeding on a green alga and four strains of cyanobacteria, differing in shape, size and toxicity

We studied the functional response of the freshwater unionid bivalve Anodonta anatina, feeding on five phytoplankton strains differing in food quality: the small green alga Scenedesmus obliquus, a toxic and a non-toxic strain of the filamentous cyanobacterium Planktothrix agardhii and a toxic and a non-toxic strain of the coccoid cyanobacterium Microcystis aeruginosa. On S. obliquus, A. anatina had a type II functional response with a maximum mass-specific ingestion rate (IR_max) of 5.24 mg C g DW⁻¹ h⁻¹ and a maximum mass-specific clearance rate (CR_max) of 492 (±38) ml g DW⁻¹ h⁻¹, the highest values for all the phytoplankton strains that were investigated. On toxic and non-toxic P. agardhii filaments, A. anatina also had a type II functional response, but IR_max and CR_max were considerably lower (IR_max 1.90 and 1.56 mg C g DW⁻¹ h⁻¹; CR_max 387 (±97) and 429 (±71) ml g DW⁻¹ h⁻¹, respectively) than on S. obliquus. Toxicity of P. agardhii had no effect on the filtration rate of the mussels. On the non-toxic M. aeruginosa (small coccoid cells), we also observed a type II functional response, although a type I functional response fitted almost as good to these data. For the colonial and toxic M. aeruginosa, a type I functional response fitted best to the data: IR increased linearly with food concentration and CR remained constant. CR_max and IR_max values for the (colonial) toxic M. aeruginosa (383 (±40) ml g DW⁻¹ h⁻¹; 3.7 mg C g DW⁻¹ h⁻¹) demonstrated that A. anatina filtered and ingested this cyanobacterium as good as the other cyanobacterial strains. However, on the non-toxic M. aeruginosa we observed the lowest CR_max of all phytoplankters (246 (±23) ml g DW⁻¹ h⁻¹, whereas IR_max was similar to that on toxic M. aeruginosa. The high maximum ingestion rates on S. obliquus and M. aeruginosa indicate a short handling time of these phytoplankton species. The high clearance rates on S. obliquus, toxic M. aeruginosa and P. agardhii reflect a high effort of the mussels to filter these particles out of the water column at low concentrations. The low clearance rates on non-toxic M. aeruginosa may be explained by the small size and coccoid form of this cyanobacterium, which may have impaired A. anatina to efficiently capture the cells. Although A. anatina had relatively high maximum clearance rates on non-toxic and toxic P. agardhii, this cyanobacterium does not seem to be a good food source, because of the observed high rates of pseudofaeces production and hence low ingestion rates.     

Phylogenetic relationships of nonaxenic filamentous cyanobacterial strains based on 16S rRNA sequence analysis

In order to determine the nearly complete 16S rRNA gene sequences of cyanobacteria originating from nonaxenic cultures, a cyanobacterium-specific oligonucleotide probe was developed to distinguish polymerase chain reaction (PCR) products of the cyanobacterial rRNA operons from those resulting from amplification of contaminating bacteria. Using this screening method the 16S rRNA genes of four nonaxenic filamentous cyanobacterial strains belonging to the generaLeptolyngbya andOscillatoria were cloned and sequenced. For the genusLeptolyngbya, the 16S rRNA sequence of the axenic strain PCC 73110 was also determined. Phylogenetic trees were constructed based on complete and partial sequences. The results show that the strainsLeptolyngbya foveolarum Komárek 1964/112,Leptolyngbya sp. VRUC 135 Albertano 1985/1, andLeptolyngbya boryanum PCC 73110 belong to the same cluster. StrainOscillatoria cf.corallinae SAG 8.92, which contains the rare photosynthetic pigment CU-phycoerythrin, is not closely related to other CU-phycoerythrin-containing cyanobacteria.Oscillatoria agardhii CYA 18, which is a representative of planktonicOscillatoria species that form toxic blooms in Norwegian inland waters, has no close relatives in the tree.     

Lack of relationship between gliding cyanobacteria and filamentous gliding heterotrophic eubacteria: comparison of 16S rRNA catalogues of Spirulina,Saprospira, Vitreoscilla,Leucothrix, and Herpetosiphon

Spirulina platensis and Spirulina maxima were characterized by 16S ribosomal RNA oligonucleotide cataloguing. Both species are highly related. They fall into the main group of the cyanobacteria, showing a remote relationship to Nostoc, Fischerella, Aphanocapsa, and also to Prochloron. Low similarity coefficients were found between the Spirulina species and certain organotrophic and sulfide oxidizing bacteria, viz. Saprospira grandis, Vitreoscilla stercoraria, Leucothrix mucor, Herpetosiphon aurantiacus, and Beggiatoa leptomitiformis, respectively. This result does not support the classical hypothesis that certain filamentous gliding bacteria are apochlorotic cyanobacteria.     

Production of amino acids by free-living heterotrophic nitrogen-fixing bacteria

Summary Interest of microbial production of amino acids has been increased greatly since development of biotechnological methods. These methods represent a perspective way applied in a future large-scale manufacture of inexpensive amino acids. In this context, the isolation of producing organisms that may be exploited in the desing of alternative methods for the production of amino acids could be of primary importance.In this review we will describe the liberation of amino acids (methionine, lysine, arginine, tryptophane and glutamic acid) byAzotobacter andAzospirillum during growth in culture media with different carbon sources under diazotrophic and adiazotrophic conditions. These organisms may be useful in developing new methods for the industrial production of amino acids.     

Composition of cyclic peptide toxins among strains ofMicrocystis aeruginosa (blue-green algae,cyanobacteria)

The distribution of the cyclic heptapeptide toxin, microcystin, was studied among 31 strains of Microcystis aeruginosa. Microcystins-RR, -YR and -LR were detected in fifteen strains and microcystin-LR was in two strains, but no toxin was found in fourteen strains. All three toxins were detected in all 12 strains belonging to the large cell-size group recognized by cell size and allozyme genotype. This pattern of toxin composition is compatible with that of M. viridis. The small cell-size group showed variation in the toxin composition as in the case of allozyme genotype.     

Effect of <Emphasis Type="Italic">Nostoc</Emphasis> sp. on soil characteristics,plant growth and nutrient uptake

The arid desert area is expanding by 6 million ha year⁻¹. Nostoc, a terrestrial cyanobacterium, is known as a pioneer organism which can photosynthesize, fix atmospheric nitrogen, and secrete polysaccharides. In order to explore the potential of Nostoc as a countermeasure to soil desertification, we have investigated the effects of Nostoc on the chemical and physical properties of soil and on plant growth in outdoor and laboratory experiments. The effect of Nostoc on soil properties, when applied on the surface of soil in plastic containers, was determined after cultivation for 90 days outdoors. Its effect on plant growth and nutrient uptake was determined by growing Nostoc with Komatsuna (Brassica rapa var. peruviridis) on a soil-less culture in a plastic petri dish incubated inside a growth chamber for 14 days. Two colonies of Nostoc with different shapes were also examined for their tolerance to dryness and salinity. Nostoc application resulted in an increase in the organic carbon and nitrogen content of the surface soil and enhanced plant growth and plant iron uptake, but soil temperature and moisture were maintained. Spherical-shaped Nostoc showed a higher tolerance to dryness and salinity than irregular-shaped Nostoc, and the former was able to rectify problematic soil better than the latter. The results indicate that the application of Nostoc to soil has a potential for increasing soil organic matter and reclaiming degraded soil ecosystems. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Purification and effects of fulvocin C,a bacteriocin from Myxococcus fulvus Mx f16

Fulvocin C is a bacteriocin from Myxococcus fulvus Mx f16. It has a molecular weight of 4672 and is one of the smallest bacteriocins known. Four disulfide bonds give the molecule a tight structure, so that its native form was not attacked by chymotrypsin or pronase. Fulvocin C was stable in various organic solvents and could tolerate 80° C in aqueous solution without loss of activity. The killing effect of fulvocin C was observed only at concentrations higher than 0.25 mol/l. Macromolecular synthesis (DNA, RNA, protein) was affected very gradually. Viability in growing cultures decreased slowly from 100 to 25% during one generation (8 h). Cell division was affected early. After one generation v-shaped cell pairs had accumulated in the culture. Electron microscopic pictures revealed extended membrane systems connected with the inner membrane. The most striking effect was that often the outer membranes of neighbouring cells seemed to have fused laterally. With further incubation many cells lost their rod shape and empty bags became predominant.Abbreviations cas lm Casitone liquid medium - O.D. optical density - SDS dodecyl sulfate, sodium salt - TCA trichloro-acetic acid     

In vitro study on bacteriocin production of Enterococci associated with chickens

In recent years, the approach of using innovative strategies such as probiotics or bacteriocins for the prevention or treatment of bacterial infections has come into focus. The present study was undertaken to check in vitro ability of Enterococci-isolated from the gastrointestinal tract of chickens-to produce a bacteriocin-like substance and to describe some further probiotic properties in five selected Enterococcus faecium strains. All strains (n=17) were found to produce bacteriocin-like substances against 14 out of 20 indicator bacteria of animal, food or environmental origin. Selected E. faecium strains expressed sufficient survival by pH 3.0 after 3h, in the presence of 1% bile after 24h and they were sensitive to most of antimicrobials tested. All tested strains adhere to the human, canine and porcine intestinal mucus (between 1.5% and 9.2%). However, better adhesion ability was observed for the canine mucus. PCR detection of enterocin structural genes determined presence of enterocins A and P genes in all selected strains. Characterization of bacteriocin substance in detail was performed in E. faecium EF55. The EF55 strain produced a bacteriocin-like substance (during the late logarithmic and early stationary growth phase) with inhibitory activity mostly against Gram-positive bacteria (100-51,200 AU/mL) including Listeria monocytogenes. Proteinaceous character of the bacteriocin substance was confirmed (its inhibitory activity was lost after its treatment with proteases), it was found to be stable after heating (100 degrees C 10 min) and during 12 months storage at -20 degrees C. The highest inhibitory activity of bacteriocin produced by EF55 strain (growing in MRS) broth was achieved between pH 7.0 and 9.0.     

3种水稻土中7株固氮蓝细菌的分离与特征

【背景】蓝细菌是水生和陆地生态系统中生物固氮的主要贡献者。【目的】增加对稻田土壤固氮蓝细菌的了解,获得用于进一步研究的可培养固氮蓝细菌菌株。【方法】选择3种具有不同固氮能力的水稻土,采用BG11-N培养基分离培养固氮蓝细菌菌株,对新分离菌株进行形态特征观察,通过基因组DNA的nifH基因扩增明确其固氮潜力,进一步采用乙炔还原法和~(15)N_2示踪法定量测定其固氮能力,通过基因组DNA的16SrRNA基因序列比对进行鉴定。【结果】在光照培养条件下,采用BG11-N培养基共分离纯化得到自养菌株7株,细胞呈圆形或椭圆形、单列、无分枝、丝状和念珠状,在固体培养基上形成团垫状菌落。新分离菌株在BG11-N培养基中生长状况良好,以基因组DNA为模板可扩增出nifH基因,乙炔还原法和~(15)N_2示踪法测定结果显示具有较高固氮能力,同时具有铁载体生成能力。结合16S rRNA基因序列比对和形态特征,7株菌被初步鉴定隶属于念珠藻科(Nostocaceae)。【结论】从水稻土中分离到在稻田生物固氮中发挥重要作用的蓝细菌(念珠藻科)菌株,可培养固氮蓝细菌菌株固氮能力较高,兼具铁载体生成能力,可作为进一步深入研究的微生物资源,具有潜在的研究应用价值。