大连海域沉积物中可培养海洋链霉菌活性及其多样性

以大肠杆菌、金黄色葡萄球菌和尖孢镰刀枯萎病菌作为测试靶目标,采用9种分离培养基从大连海域13个不同采样点的海洋沉积物样品中分离到165株海洋链霉菌。从165株海洋放线菌中筛选到对金黄色葡萄球菌具有抑制活性的菌株85株,占总菌株数的51.5%;对大肠杆菌具有抑制活性的菌株27株,占总菌株数的16.4%;对尖孢镰刀枯萎病菌具有抑制活性的菌株仅有6株,占总菌株数的3.6%。因此,海洋链霉菌的活性更多地表现为对细菌的抗性,尤其对革兰氏阳性细菌具有更高的抑制活性。对其中具有抑制活性或形态独特的菌株进行了16S r DNA序列分析,并构建系统发育树,显示活性海洋链霉菌具有丰富的种类多样性和广谱抗菌活性。同种海洋链霉菌与土壤链霉菌活性比较结果也表明,海洋链霉菌多表现抗革兰氏阳性细菌活性。     

Northward expansion of a marine parasite: Testing the role of temperature adaptation

The known range of the eastern oyster (Crassostrea virginica) parasite, Perkinsus marinus, expanded into the northeastern United States in the early 1990s. We used both in vitro and in vivo data to test the hypothesis that the northward expansion was associated with a low-temperature adapted strain of the parasite. In vitro proliferation of nine P. marinus isolates from three geographic sites, Massachusetts and New Jersey in the new range, and South Carolina in the historic southern range, was measured at seven temperatures (5 to 35 °C) using a tetrazolium blue dye assay. We wanted to determine if there were between- and within-geographic location differences in the P. marinus proliferation rate, and if so, whether they were associated with temperature. We found no evidence of low-temperature adaptation based on the fact that net proliferation rates for isolates from all three geographic locations were similar at temperatures from 5 to 20 °C. On the other hand, at temperatures of 25 to 35 °C, the South Carolina isolates exhibited higher proliferation rates than the northern isolates suggesting possible high-temperature adaptation of parasite strains that are routinely exposed to higher temperatures. Although there was significant within-location variation among isolates, the data tended to group together by geographic location supporting the hypothesis that there is an important regional component to the proliferation rate of P. marinus isolates. A survey of published data showed that the temperature at which in vivo proliferation was first observed in oysters at sites from the Gulf of Mexico to Massachusetts was typically between 20 and 23 °C with no evidence of a geographic cline. These results lend support to the hypothesis that the recent warming trend in the northeastern US is the most likely explanation for the P. marinus range extension.     

Insect-toxic secreted proteins and virulence of the entomopathogenic fungus Beauveria bassiana

Fungal virulence has been mostly associated with cuticle-degrading enzymes that can be regulated depending on nutrient conditions. However, few studies have related fungal virulence to insect-toxic secreted proteins. Here, we describe how the presence of secreted toxic proteins may be linked to conidial virulence, which can be affected by nutrient factors. In this study we evaluated: (1) the virulence of the conidia of four Beauveria bassiana strains (EABb 01/103-Su, EABb 01/12-Su, EABb 01/88-Su and EABb 01/110-Su) grown on three different media (malt extract agar (MA), Rice (Rice), Sabouraud dextrose agar (SDA) and harvested from the cadavers of fungal-infected Galleria mellonella larvae (CAD) and (2) the toxicity of the crude soluble protein extracts (CSPEs) obtained from Adamek’s liquid medium inoculated with these conidia. Conidial suspensions were obtained from the four media, assessed on G. mellonella larvae and used to produce CSPEs that were injected into healthy G. mellonella larvae. The larvae were also injected with conidia obtained from MA and CAD cultures to expose them to in vivo-secreted proteins. For all isolates, the CAD conidia were by far the most virulent, followed by conidia grown on SDA, Rice and MA. The injected CSPEs showed the same toxicity trends as the conidial suspensions. In addition, the outcomes of injection of the in vivo-secreted proteins showed that the toxic proteins secreted in vitro by the EABb 01/110-Su strain are not produced in vivo. However, the other strains produced toxic proteins both in vivo and in vitro, suggesting that these toxic proteins may be virulence factors involved in invertebrate pathogenesis.     

A novel GFP-based approach for screening biocontrol microorganisms in vitro against Dothistroma septosporum

Dothistroma septosporum is the causal agent of Dothistroma needle blight of pine trees. A novel green fluorescent protein (GFP)-based screening method was developed to assess the potential of microorganisms for biocontrol of Dothistroma. The screen utilizes GFP expression as an indicator of metabolic activity in the pathogen and hygromycin resistance selection to determine if the interaction is fungistatic or fungicidal. Results suggested that six of eight Trichoderma isolates tested have the potential to control Dothistroma in vitro, via a fungicidal action. Because D. septosporum produces a broad-spectrum toxin, dothistromin, the inhibition of Trichoderma spp. by D. septosporum was determined by growth rate measurements compared to controls. Inhibition of the Trichoderma spp. ranged from no inhibition to 30% inhibition and was influenced by the assay medium used. The GFP screening method was also assessed to determine if it was suitable for screening bacteria as potential biocontrol candidates. Although a method involving indirect-contact had to be used, two of four Bacillus strains showed antagonistic activity against D. septosporum in vitro, via a fungistatic interaction. The four bacterial strains inhibited D. septosporum growth by 14.0 to 39.8%. This GFP-based method represents a novel approach to screening fungi and bacteria for antagonistic activity.     

Endophytic occupation of peanut root nodules by opportunistic Gammaproteobacteria

Several bacterial isolates were recovered from surface-sterilized root nodules of Arachis hypogaea L. (peanut) plants growing in soils from Córdoba, Argentina. The 16S rDNA sequences of seven fast-growing strains were obtained and the phylogenetic analysis showed that these isolates belonged to the Phylum Proteobacteria, Class Gammaproteobacteria, and included Pseudomonas spp., Enterobacter spp., and Klebsiella spp. After storage, these strains became unable to induce nodule formation in Arachis hypogaea L. plants, but they enhanced plant yield. When the isolates were co-inoculated with an infective Bradyrhizobium strain, they were even found colonizing pre-formed nodules. Analysis of symbiotic genes showed that the nifH gene was only detected for the Klebsiella-like isolates and the nodC gene could not be amplified by PCR or be detected by Southern blotting in any of the isolates. The results obtained support the idea that these isolates are opportunistic bacteria able to colonize nodules induced by rhizobia.     

Toxocara canis: Potential activity of natural products against second-stage larvae in vitro and in vivo

The anthelmintic activity of extracts from Chenopodiumambrosioides, Pycnanthusangolensis and Nutridesintox® was in vitro and in vivo investigated, against Toxocaracanis larvae. The in vitro assays results showed that the aqueous extract of Nutridesintox® was the most effective, followed by C. ambrosioides extracts, hexane, dichloromethane and the infusion. P. angolensis extracts showed a lower anthelmintic activity compared to the other natural products. For the in vivo assays, Nutridesintox®, the hexane extract and the infusion of C. ambrosioides were administered orally to T. canis-infected mice, in single doses, during three consecutive days. The efficacy was evaluated on the 17th day post-infection, not only by counting T. canis larvae in the tissues but also by ELISA detection of IgM and IgG antibodies and histological analysis of liver and lungs. The different treatments did not reduce the larvae burden and had no influence on the antibodies dynamic. Interestingly, a reduction on the inflammatory infiltrates was observed in the liver and lung sections of the group treated with the hexane extract of C. ambrosioides. In conclusion, the hexane extract of C. ambrosioides is of further research interest, as it showed an anthelmintic activity in vitro and a reduction on the inflammatory reaction produced by the infection of T. canis larvae in vivo.     

Steinernema carpocapsae DD136: metabolites limit the non-self adhesion responses of haemocytes of two lepidopteran larvae, Galleria mellonella (F. Pyralidae) and Malacosoma disstria (F. Lasiocampidae)

Live adult and juvenile entomopathogenic Steinernema carpocapsae DD136 (P. Nematoda) were not subjected to adhesion by haemocytes of lepidopteran insect larvae of Galleria mellonella or Malacosoma disstriain vitro or in vivo. In vitro freeze-killed nematodes exhibited haemocyte attachment, the intensity increasing with time. Accumulation of haemocytes on the dead nematodes was associated with host phenoloxidase activity; live nematodes and their exudates did not activate the enzyme whereas dead nematodes but not their exudate did activate phenoloxidase. Live-nematode exudate inhibited granular cell and some plasmatocyte adhesion to slides, increased granular cell but not plasmatocyte dissociation from preformed haemocyte monolayers and in vivo elevated total haemocyte counts and changed the floating haemocyte types while impairing bacterial removal from the haemolymph. Dead-nematode exudate did not affect these parameters thus immunosuppressant activity by live nematodes may represent the release of inhibitors not associated with their cuticle. The third stage juveniles released the inhibitors.     

Comparative study on the delignification of Azadirachta indica (L) Del., wood by Chrysosporium asperatum and Trichoderma harzianum

Structural alterations induced in response to degradation by two white rot Basidiomycetes on the secondary xylem of Azadirachta indica (L) Del., was compared. In vitro decay test was employed to investigate the pattern of delignification of Azadirachta wood by Trichoderma harzianum and Chrysosporium asperatum. Wood samples inoculated with both the strains were analyzed for different periods viz. 30, 60, 90 and 120 days after fungal inoculation. Initially there was no appreciable percent weight loss of the wood blocks but later on (after 60 days) it increased rapidly and was found similar for both the strains (43-46% of wood mass). Samples inoculated with both the strains showed dual pattern of degradation i.e. selective delignification in the initial stage followed by simultaneous rot during advance stage of decay. Separation of the cells due to dissolution of middle lamella was the characteristic feature of both strains but in the advanced stage of decay, formation of erosion troughs were conspicuous in all the cell types. Other features such as cell wall thinning, rounded pit erosion, formation of erosion channels and bore holes were also observed frequently. Initially, fungal invasion started through the vessel lumen, followed by all the cell types of the xylem. From the vessels, mycelia entered into the adjacent rays and parenchyma cells through the pits. In advanced stage, degradation was so pronounced that rays were partially or even completely destroyed while many cells including vessels were either deformed or destroyed due to loss of rigidity of their walls. Structural alterations induced in response to C. asperatum and T. harzianum attack is described in details.     

Sequence Diversity in MIC6 Gene among Toxoplasma gondii Isolates from Different Hosts and Geographical Locations

Toxoplasma gondii is an opportunistic protozoan parasite that can infect almost all warm-blooded animals including humans with a worldwide distribution. Micronemes play an important role in invasion process of T. gondii, associated with the attachment, motility, and host cell recognition. In this research, sequence diversity in microneme protein 6 (MIC6) gene among 16 T. gondii isolates from different hosts and geographical regions and 1 reference strain was examined. The results showed that the sequence of all the examined T. gondii strains was 1,050 bp in length, and their A + T content was between 45.7% and 46.1%. Sequence analysis presented 33 nucleotide mutation positions (0-1.1%), resulting in 23 amino acid substitutions (0-2.3%) aligned with T. gondii RH strain. Moreover, T. gondii strains representing the 3 classical genotypes (Type I, II, and III) were separated into different clusters based on the locus of MIC6 using phylogenetic analyses by Bayesian inference (BI), maximum parsimony (MP), and maximum likelihood (ML), but T. gondii strains belonging to ToxoDB #9 were separated into different clusters. Our results suggested that MIC6 gene is not a suitable marker for T. gondii population genetic studies.     

Biocontrol efficacy of Trichoderma spp. against sesame wilt caused by Fusarium oxysporum f. sp. sesami

Sesame (Sesamum indicum L.) is one of the most important oilseed crops in Egypt and worldwide. It is being infected with many pathogens, among these pathogens Fusarium oxysporum f.sp. sesami (Zap.) Cast is causing severe economic losses on sesame. In this study, antagonistic capability of 24 isolates of Trichoderma spp. was assessed in vitro against F. oxysporum f.sp. sesami. Two strains; T. harzianum (T9) and T. viride (T21) were revealed to have high antagonistic effect against F. oxysporum f.sp. sesami in vitro with inhibition percentage about 70 and 67%, respectively. These two isolates proved to have high ability to control Fusarium wilt disease under greenhouse conditions. The highest reduction in disease severity was achieved with T. viride followed by T. harzianum with reduction in disease severity about 77 and 74%, respectively. This study revealed that the time of application of bioagents is a decisive factor in determining the efficacy of Trichoderma isolates to control Fusarium wilt of sesame. It was revealed that the highest reduction in the disease severity was achieved when either Trichoderma viride or T. harzianum were applied 7 days before challenging with the F. oxysporum f.sp. sesami.     

Leishmania donovani: Genetic diversity of isolates from Sudan characterized by PCR-based RAPD

Drug unresponsiveness in patients with visceral leishmaniasis (VL) is a problem in many endemic areas. This study aimed to determine genetic diversity of Leishmania donovani isolates from a VL endemic area in Sudan as a possible explanation for drug unresponsiveness in some patients. Thirty clinically stibogluconate (SSG)-sensitive isolates were made SSG-unresponsive in vitro by gradually increasing SSG concentrations. The sensitive isolates and their SSG-unresponsive counterparts were typed using mini-circle kDNA and categorized using PCR-RAPD. All the isolates were typed as L. donovani, the resulting PCR-RAPD characterization of the SSG-sensitive isolates gave three distinct primary genotypes while, the SSG-unresponsive isolates showed only a single band. L. donovani isolates from eastern Sudan are diverse; this probably resulted from emergence of new L. donovani strains during epidemics due to the pressure of widespread use of antimonials.In this communication the possible role of isolates diversity in antimonial unresponsiveness and the in vitro changing PCR-RAPD band pattern in SSG-unresponsive strains were discussed.     

Interaction between Colletotrichum falcatum pathotypes and biocontrol agents

Abstract

To select efficient antagonistic strain(s) of biocontrol agents against most of the existing pathotypes of Colletotrichum falcatum, an in vitro interaction study was carried out with 13 pathotypes, 12 isolates of Pseudomonas spp. and 6 isolates of Trichoderma spp. Antagonistic pseudomonad strains exhibited greater variation in their activity depending on the virulence of the pathotype. The lower the pathogen virulence, the higher was the antagonistic activity noticed. In general, sub-tropical pathotypes were suppressed at a comparatively higher level than the tropical pathotypes. Among the four efficient P. fluorescens strains selected based on their inhibitory effect against various pathotypes, ARR1G and VPT4 were effective against tropical pathotypes and FP7 showed moderate effect against all the pathotypes. The strain KKM2 was effective against sub-tropical and weaker tropical pathotypes. Strains of Trichoderma spp. did not show much variation in antagonism, but varied in their mode of action in suppressing the pathogen growth. However, based on higher rate of hyperparasitism, T. harzianum strains T5 and T62 were selected against all the pathotypes.     

Ecological characterization of entomopathogenic nematodes isolated in stone fruit orchard soils of Mediterranean areas

Entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae were isolated from stone-fruit orchards in two Mediterranean regions of Spain. A total of 630 soil samples (210 sites) from Catalonia and 90 soil samples (30 sites) from Murcia were evaluated resulting in 5.2% and 20% of the soils testing positive for nematodes, respectively. Ten steinernematid isolates and three heterorhabditid isolates were recovered using the Galleria mellonella baiting method. Based on morphometric data, molecular data, and cross-breeding experiments the nematode species were identified as Steinernemafeltiae and Heterorhabditis bacteriophora. Environmental tolerance to heat, desiccation and hypoxia, the effect of temperature on infectivity and reproduction and nematode migration in sand columns were compared among isolates and one Steinernema carpocapsae strain. Results showed differences among species and a great variability within species. Beneficial traits for each strain were added up to identify a superior candidate to control Mediterranean flat-headed rootborer, Capnodis tenebrionis. When all analyzed factors were considered, three S. feltiae isolates (Bpa, Sor and M116) obtained the best scores, and when hypoxia was removed, two of the strains (Bpa and Sor) continued ranking superior to other strains.     

Evaluation of rhizosphere bacterial antagonists for their potential to bioprotect potato (Solanum tuberosum) against bacterial wilt (Ralstonia solanacearum)

Bacterial wilt (Ralstonia solanacearum) is one of the production constraints of potato (Solanum tuberosum). The intent of the study was to evaluate potential of bacterial antagonists to suppress bacterial wilt disease development and evaluate the role of the strains as plant growth-promoting rhizobacteria (PGPR) in potato. One hundred-twenty rhizosphere bacterial isolates were screened against virulent strain of Ralstonia solanacearum PPRC-Rs. After in vitro screening, six antagonistic strains (PFMRI, BS-DFS, PF9, PF20, BC, and BS-wly) with inhibition diameter >11 mm were selected and studied further in the greenhouse, in vivo. During in vivo study, the strains were evaluated for their effect in suppressing disease development in terms of area under disease progress curve (AUDPC) and increasing biomass (plant height and dry weight) of potato. Accordingly, PFMRI, BS-DFS, and PF9, significantly reduced AUDPC by 78.6, 66, and 64.3%, and wilt incidence by 82.7, 66.2, and 65.7%, respectively, compared to the control. During the sole application, the strains significantly (P < 0.0001) increased plant height by 35.6, 45.9, and 45%, and dry matter by 111, 130.4, and 129%, respectively compared to non-bacterized control. In the presence of the pathogen strain PFMRI, BS-DFS, and PF9 increased plant height by 66, 50, and 48.2%, and dry matter by 153.8, 96.8, and 92.5%, respectively compared to the pathogen treated control. Hence, the study shows that PFMRI, BS-DFS, and PF9 strains have potential use in potato bioprotection, as PGPR or in an integrated bacterial wilt management; whose effectiveness under a variety of field conditions should be investigated.     

Arcobacter molluscorum sp. nov., a new species isolated from shellfish

Nineteen bacteria isolates recovered from shellfish samples (mussels and oysters) showed a new and specific 16S rDNA-RFLP pattern with an Arcobacter identification method designed to recognize all species described up to 2008. These results suggested that they could belong to a new species. ERIC-PCR revealed that the 19 isolates belonged to 3 different strains. The sequence of the 16S rRNA gene of a representative strain (F98-3^T) showed 97.6% similarity with the closest species Arcobacter marinus followed by Arcobacter halophilus (95.6%) and Arcobacter mytili (94.7%). The phylogenetic analysis with the16S rRNA, rpoB, gyrB and hsp60 genes placed the shellfish strains within the same cluster as the three species mentioned (also isolated from saline habitats) but they formed an independent phylogenetic line. The DDH results between strain F98-3^T and A. marinus (54.8% ± 1.05), confirmed that it represents a new species. Several biochemical tests differentiated the shellfish isolates from all other Arcobacter species. Although the new species was different from A. mytili, they shared not only the same habitat (mussels) but also the characteristic of being so far the only Arcobacter species that are simultaneously negative for urea and indoxyl acetate hydrolysis. All results supported the classification of the shellfish strains as a new species, for which the name Arcobacter molluscorum sp. nov. with the type strain F98-3^T is proposed (=CECT 7696^T = LMG 25693^T).     

Evidence for the existence of two new members of the family Chlamydiaceae and proposal of Chlamydia avium sp. nov. and Chlamydia gallinacea sp. nov.

The family Chlamydiaceae with the recombined single genus Chlamydia currently comprises nine species, all of which are obligate intracellular organisms distinguished by a unique biphasic developmental cycle. Anecdotal evidence from epidemiological surveys in flocks of poultry, pigeons and psittacine birds have indicated the presence of non-classified chlamydial strains, some of which may act as pathogens. In the present study, phylogenetic analysis of ribosomal RNA and ompA genes, as well as multi-locus sequence analysis of 11 field isolates were conducted. All independent analyses assigned the strains into two different clades of monophyletic origin corresponding to pigeon and psittacine strains or poultry isolates, respectively. Comparative genome analysis involving the type strains of currently accepted Chlamydiaceae species and the designated type strains representing the two new clades confirmed that the latter could be classified into two different species as their average nucleotide identity (ANI) values were always below 94%, both with the closest relative species and between themselves.     

Enzymes of the antioxidant network as novel determiners of Trypanosoma cruzi virulence

Virulence of Trypanosoma cruzi depends on a variety of genetic and biochemical factors. It has been proposed that components of the parasites’ antioxidant system may play a key part in this process by pre-adapting the pathogen to the oxidative environment encountered during host cell invasion. Using several isolates (10 strains) belonging to the two major phylogenetic lineages (T. cruzi-I and T. cruzi-II), we investigated whether there was an association between virulence (ranging from highly aggressive to attenuated isolates at the parasitemia and histopathological level) and the antioxidant enzyme content. Antibodies raised against trypanothione synthetase (TcTS), ascorbate peroxidase (TcAPX), mitochondrial and cytosolic tryparedoxin peroxidases (TcMPX and TcCPX) and trypanothione reductase (TcTR) were used to evaluate the antioxidant enzyme levels in epimastigote and metacyclic trypomastigote forms in the T. cruzi strains. Levels of TcCPX, TcMPX and TcTS were shown to increase during differentiation from the non-infective epimastigote to the infective metacyclic trypomastigote stage in all parasite strains examined. Peroxiredoxins were found to be present at higher levels in the metacyclic infective forms of the virulent isolates compared with the attenuated strains. Additionally, an increased resistance of epimastigotes from virulent T. cruzi populations to hydrogen peroxide and peroxynitrite challenge was observed. In mouse infection models, a direct correlation was found between protein levels of TcCPX, TcMPX and TcTS, and the parasitemia elicited by the different isolates studied (Pearson’s coefficient: 0.617, 0.771, 0.499; respectively, P < 0.01). No correlation with parasitemia was found for TcAPX and TcTR proteins in any of the strains analyzed. Our data support that enzymes of the parasite antioxidant armamentarium at the onset of infection represent new virulence factors involved in the establishment of disease.     

Interaction and ovicidal activity of nematophagous fungus Pochonia chlamydosporia on Taenia saginata eggs

The ovicidal activity of the nematophagous fungi Pochonia chlamydosporia (isolates VC1 and VC4), Duddingtonia flagrans (isolate AC001) and Monacrosporium thaumasium (isolate NF34) on Taenia saginata eggs was evaluated under laboratory conditions. T. saginata eggs were plated on 2% water-agar with fungal isolates and controls without fungus and examined after 5, 10 and 15 days. At the end of the experiment P. chlamydosporia showed ovicidal activity against T. saginata eggs (p < 0.05), mainly for internal egg colonization with results of 12.8% (VC1) and 2.2% (VC4); 18.1% (VC1) and 7.0% (VC4); 9.76% (VC1) and 8.0% (VC4) at 5, 10 and 15 days, respectively. The other fungi showed only lytic effect without morphological damage to the eggshell. Results demonstrated that P. chlamydosporia was effective in vitro against T. saginata eggs unlike the other fungi.     

Efficacy of an essential oil of Eugenia caryophyllata against Psoroptes cuniculi

The acaricidal activity of Eugenia caryophyllata essential oil was evaluated in vitro and in vivo on Psoroptes cuniculi, a mange mite. In vitro, different concentrations of the oil were tested and the observed mites mortality was compared with that observed in untreated and treated (Acacerulen R^®) controls. In vivo, six P. cuniculi infected rabbits were topically treated with the oil diluted at 2.5% and compared with untreated and treated control groups of six rabbits each. In vitro, up to the concentration of 0.10% the oil gave highly significant (P < 0.01) percentages of mite mortality respect to the untreated controls, but only up to 0.16% it showed the same efficacy of Acacerulen R^®. In vivo, the treatment with the essential oil cured all infested rabbits and no statistical differences were observed respect to the treated control group. The untreated rabbits remained infested.     

Rubrimonas shengliensis sp. nov. and Polymorphum gilvum gen. nov., sp. nov., novel members of Alphaproteobacteria from crude oil contaminated saline soil

Four bacterial strains were isolated from a crude oil contaminated saline soil in Shengli Oilfield, China. Strains SL014B-28A2^T and SL014B-80A1 were most closely related to Rubrimonas cliftonensis OCh 317^T, while strains SL003B-26A1^T and SL003B-26A2 were most closely related to but readily different from the species in the Pannonibacter-Labrenzia-Roseibium-Stappia cluster. The major fatty acids were C_18:1ω7c, C_16:0, C_18:0 and 11-Methyl C_18:1ω7c, and C_18:1ω7c, 11-Methyl C_18:1ω7c and C_18:0, respectively, for these two groups of isolates. Q-10 was the predominant ubiquinone. The G + C contents of genomic DNA of the four isolates were 67.9, 69.7, 65.6 and 65.6 mol%. Based on the polyphasic taxonomic characteristics, strains SL014B-28A2^T and SL014B-80A1 represented a novel species of the genus Rubrimonas, for which the name Rubrimonas shengliensis sp. nov. is proposed, with strain SL014B-28A2^T (=LMG 26072^T = CGMCC 1.9170^T) as the type strain. Isolates SL003B-26A1^T and SL003B-26A2 represented a novel genus and species of the family Rhodobacteraceae, for which the name Polymorphum gilvum gen. nov., sp. nov. is proposed, with strain SL003B-26A1^T (=LMG 25793^T = CGMCC 1.9160^T) as the type strain.