Plant growth promoting potential of the fungus <Emphasis Type="Italic">Discosia</Emphasis> sp. FIHB 571 from tea rhizosphere tested on chickpea,maize and pea

The ITS region sequence of a phosphate-solubilizing fungus isolated from the rhizosphere of tea growing in Kangra valley of Himachal Pradesh showed 96% identity with Discosia sp. strain HKUCC 6626 ITS 1, 5.8S rRNA gene and ITS 2 complete sequence, and 28S rRNA gene partial sequence. The fungus exhibited the multiple plant growth promoting attributes of solubilization of inorganic phosphate substrates, production of phytase and siderophores, and biosynthesis of indole acetic acid (IAA)-like auxins. The fungal inoculum significantly increased the root length, shoot length and dry matter in the test plants of maize, pea and chickpea over the uninoculated control under the controlled environment. The plant growth promoting attributes have not been previously studied for the fungus. The fungal strain with its multiple plant growth promoting activities appears attractive towards the development of microbial inoculants.     

一株高效解磷真菌新菌株的筛选鉴定及解磷特性

从辽宁省辽中县多年耕种的日光温室番茄根际土壤中筛选出一株解磷真菌,通过菌落形态特征和ITS rDNA序列对比,鉴定该菌株为草酸青霉菌的一株新菌株,将其命名为PSF1.该菌株能利用葡萄糖、蔗糖、乳糖、半乳糖、可溶性淀粉等多种碳源和硫酸铵、氯化铵、硝酸铵、硝酸钾、尿素等多种氮源进行生长代谢并表现出较强的解磷能力,在C/N 10∶1~60∶1、初始pH 7~8的条件下生长情况较好且解磷能力较高.该菌株有很强的产酸能力,在培养过程中培养液pH由7.00~7.50下降至2.06~4.87;在4种磷源培养液中的最高解磷量分别为磷酸三钙(869.62 mg·L^-1)>磷矿粉(233.56 mg·L^-1)>磷酸铝(44.77 mg·L^-1)>磷酸铁(28.42 mg·L^-1).Pearson相关分析表明,菌株在磷酸三钙、磷矿粉和磷酸铁培养液中的解磷量与pH的变化之间呈极显著负相关关系,在磷酸铝培养液中无显著相关关系.菌株PSF1解磷能力强,生长条件广,推测其在土壤中有较强的解磷能力.     

Characterization of Phosphate-Solubilizing Fluorescent Pseudomonads from the Rhizosphere of Seabuckthorn Growing in the Cold Deserts of Himalayas

Isolation and characterization of fluorescent pseudomonads with high phosphate-solubilizing ability is reported from the alkaline and calcium-rich soils with low P availability in the cold desert region of Lahaul and Spiti in the trans-Himalayas of India. Of 216 phosphate-solubilizing isolates, 12 exhibiting high solubilization of tricalcium phosphate (TCP) in NBRIP liquid culture were identified as Pseudomonas trivialis, P. poae, P. fluorescens, and Pseudomonas spp. on the basis of phenotypic features, whole-cell fatty acids methyl ester (FAME) profiles, and 16S rDNA sequencing. These isolates also showed relatively high solubilization of North Carolina rock phosphate (NCRP) in comparison to the solubilization of Mussoorie rock phosphate (MRP) and Udaipur rock phosphate (URP). The solubilization of phosphate substrates by P. trivialis and P. poae is reported for the first time.     

Characterization of plant-growth promoting diazotrophic bacteria isolated from field grown Chinese cabbage under different fertilization conditions

Diazotrophic bacteria isolated from the rhizosphere of Chinese cabbage were assessed for other plant growth promoting characteristics viz., production of IAA, ethylene, ACC deaminase, phosphate solubilization, and gnotobiotic root elongation. Their effect on inoculation to Chinese cabbage was also observed under growth chamber conditions. A total of 19 strains that showed higher nitrogenase activity identified by 16S rRNA gene sequence analysis were found to be the members of the genera Pseudomonas and Agrobacterium belonging to α- and γ-Proteobacteria groups. These strains were also efficient in producing IAA and ACC deaminase though they produced low levels of ethylene and no phosphate solubilization. In addition, inoculation of selected diazotrophic bacterial strains significantly increased seedling length, dry weight, and total nitrogen when compared to uninoculated control. The colonization of crop plants by diazotrophic bacteria can be affected by many biotic and abiotic factors, and further studies are oriented towards investigating the factors that could influence the establishment of a selected bacterial community.     

Isolation of a starch utilizing, phosphate solubilizing fungus on buffered medium and its characterization

A phosphate solubilizing fungus, Paecilomyces marquandii AA1 was isolated from phosphate deficient soil on Pikovskaya's medium buffered with Tris-HCl pH 8. The organism was identified on the basis of morphological characterization and by sequencing of 18S rRNA gene. The organism could release phosphate from both buffered and unbuffered medium and solubilized rock phosphates from various places. The effect of concentration of ore, temperature, carbon and nitrogen sources on solubilization of rock phosphate was studied. Ammonium salts were the best nitrogen source, followed by asparagine, sodium nitrate, potassium nitrate, urea and calcium nitrate in that order.     

Isolation and performance evaluation of halotolerant phosphate solubilizing bacteria from the rhizospheric soils of historic Dagong Brine Well in China

The use of halotolerant phosphate solubilizing bacteria as inoculants to convert insoluble phosphorus of salt-affected soils to an accessible form is a promising strategy to improve the phosphorus ingestion of plants in salt-affected agriculture. A total of four aerobic isolates with biggest clear halos on the 10% NaCl NBRIP medium plate containing tricalcium phosphate were isolated from the rhizospheric soils of native plants growing on the wall of Dagong Ancinet Brine Well, located in Sichuan of China. And these four isolates were classified to the same strain, named QW10-11, and closely related to Bacillus megatherium var. phosphaticum DSM 3228 and B. megaterium ATCC 14581 according to their phenotype and 16S rRNA. However, the Molecular evolutionary evidences of 16S-23S rRNA ISR further suggested that QW10-11, DSM 3228 and ATCC 14581 have respectively fall into the different sub-divisions in intra specific phylogeny. Strain QW10-11 has significantly better ability of tricalcium phosphate solubilization than that of lecithin solubilization. When it grows under pH 4.8–8.0, 24–33°C and 5–10% NaCl, it can exhibit the higher values of solubilized tricalcium phosphate between 59.3 and 71.4 μg ml⁻¹. Furthermore, its tricalcium phosphate solubilizing activity was associated with the release of organic acids. Taken together, our results indicted that QW10-11 from the rhizospheric soils of halobiot of Dagong Ancinet Brine Well is attractive as efficient phosphate solubilizing candidates in the salt-affected agriculture.     

Isolated Phosphate-Solubilizing Soil Bacteria Promotes In vitro Growth of Solanum tuberosum L.

The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.Key words: Bacillus sp., phosphorus soluble, Pikovskaya agar, potato rhizosphere, plant growth promoting rhizobacteria     

Molecular phylogenetic and morphological analyses of Oidium heveae, a powdery mildew of rubber tree

Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion.     

Cold-adapted and rhizosphere-competent strain of Rahnella sp. with broad-spectrum plant growth-promotion potential

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1- carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole- 3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3- pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of coldtolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.     

Population of <Emphasis Type="Italic">Aphanizomenon</Emphasis> from the Gulf of Gdańsk (Southern Baltic Sea): differences in phenotypic and genotypic characteristics

In this study, one of the major bloom-forming cyanobacteria in the Gulf of Gdańsk (Southern Baltic Sea), Aphanizomenon Morren ex Bornet et Flahaut has been characterized using a polyphasic approach by comparing phenotypic and molecular characteristics. The phenotypic analysis dealt with cell and filament morphology as well as ultrastructure. The molecular phylogenetic analyses were based on sequences of the 16S rRNA gene and the adjacent intergenic transcribed spacer (ITS). We have found the Aphanizomenon population from the Gulf of Gdańsk to be significantly different in ultrastructure, morphology from freshwater A. flos-aquae and according to the traditional approach; it could be assigned to different taxonomic units. However, genetic relationship with regard to sequences of the 16S rRNA gene, showed an high overall sequence identity (97.5–99%) to freshwater isolates. Similarly, ITS sequence identity among populations from the Baltic Sea and different freshwater isolates was as high as 90.3–97.7% suggesting one and the same species. Handling editor: D. Hamilton An erratum to this article can be found at     

Phosphate solubilization by <Emphasis Type="Italic">Rhizobium</Emphasis> strains

Forty-six Rhizobium isolates from legume root and stem nodules were examined for their phosphate-solubilizing ability on Pikovskaya’s agar medium. Rhizobium isolates from root nodules of Cassia absus, Vigna trilobata and three strains from Sesbania sesban showed zone of tricalcium phosphate (TCP) solubilization. The isolate from C. absus showed maximum solubilization (620 μg/ml) after 12 d of incubation, while the Rhizobium sp. strain 26 (from S. sesban) showed the least amount (150 μg/ml) of phosphate solubilization. Among the carbon sources tested for their ability to solubilize TCP, maximum solubilization (620 μg/ml) was observed in glucose by Rhizobium isolate from C. absus. Phosphate solubilization increased with increase in glucose concentration steeply up to 2% and slowly above this concentration in four isolates. Among the nitrogen sources tested, maximum solubilization (620 μg/ml) was observed in ammonium sulphate by Rhizobium isolate from C. absus.     

Efficient phosphorus solubilization by mutant strain of Xanthomonas campestris using different carbon, nitrogen and phosphorus sources

The phosphate solubilization activity of Xanthomonas campestris was measured in both the wild type and mutant strains using various carbon and nitrogen sources. Glucose was found to be the best in both (wild 39.9%; mutant 67.1%) strains followed by sucrose (46.8%) in the mutant and molasses (36.0%) in the wild type. Ammonium sulphate was the best nitrogen source for both the strains, followed by ammonium nitrate and urea. Dicalcium phosphate (DCP) was solubilized maximally by both the strains followed by tricalcium phosphate (TCP) and rock phosphate (RP) when various concentrations of different phosphate sources were tested.     

Isolation and characterisation of phosphate solubilising microorganisms from the cold desert habitat of <Emphasis Type="Italic">Salix alba Linn.</Emphasis> in trans Himalayan region of Himachal Pradesh

Phosphate solubilising microorganisms (PSM) (bacteria and fungi) associated with Salix alba Linn. from Lahaul and Spiti valleys of Himachal Pradesh were isolated on Pikovskaya (PVK), modified Pikovskaya (MPVK) and National Botanical Research Institute agar (NBRIP) media by spread plating. The viable colony count of P-solubilising bacteria (PSB) and fungi (PSF) was higher in rhizosphere than that of non-rhizosphere. The frequency of PSM was highest on MPVK followed by NBRIP and PVK agar. The maximum proportion of PSM out of total bacterial and fungal count was found in upper Keylong while the least in Rong Tong. The PSB frequently were Gram-positive, endosporeforming, motile rods and belonged to Bacillus sp. The PSF mainly belonged to Penicillium sp., Aspergillus fumigatus, A. niger, A. spp. and non-sporulating sterile. Amongst the isolates with high efficiency for tricalcium phosphate (TCP) solubilisation, seven bacterial and seven fungal isolates dissolved higher amount of P from North Carolina rock phosphate (NCRP) than Mussoorie rock phosphate (MRP) and Udaipur rock phosphate (URP). However, the organisms solubilised higher-P in NBRIP broth than PVK broth. SBC5 (Bacillus sp.) and SBC7 (Bacillus sp.) bacterial isolates exhibited maximun P solubilisation (40 and 33 μg ml⁻¹ respectively) whereas FC28 (Penicillium sp.) isolate (52.3 μg ml⁻¹) amongst fungi while solubilising URP. The amount of P solubilised was positively correlated with the decrease in pH of medium. SBC5 (Bacillus sp.), SBC7 (Bacillus sp.) and SBC4 (Micrococcus) decreased the pH of medium from 6.8 to 6.08 while FC28 (Penicillium sp.) and FC39 (Penicillium sp.) isolates of fungi recorded maximum decrease in pH of medium from 6.8 to 5.96 in NBRIP broth.     

Growth Enhancement of Chickpea in Saline Soils Using Plant Growth-Promoting Rhizobacteria

Bacterial isolates with the ability to tolerate salinity and plant growth-promoting features were isolated from the saline areas of Gujarat, India, that is, Bhavnagar and Khambat. A total of 176 strains of rhizobacteria were isolated out of which 62 bacterial strains were able to tolerate 1 M NaCl. These were then further studied for their potential plant growth-promoting rhizobacteria characteristics like phosphate solubilization, siderophore production, and IAA production. Twenty-eight isolates of the 62 strains showed good tricalcium phosphate solubilization in solid medium in the range of 9–22 mm and 15 isolates showed good phosphate solubilization in liquid medium in the range of 9–45 μg/ml. Siderophore production was checked in all 15 isolates, and 13 were screened out that produced the hydroxamate type of siderophore in the range of 11–50 mM. Among the 13 isolates, 10 were able to produce indole acetic acid in the range of 10–26 μg/ml after 72 h of incubation. Pot trials were carried out on chickpea under 300 mM NaCl stress using the best five isolates. Plants inoculated with MSC1 or MSC4 isolates showed an increase in the parameters that evaluate plant growth when compared to uninoculated controls. Strains MSC1 and MSC4 were identified as Pseudomonas putida and Pseudomonas pseudoalcaligens, respectively, according to sequence analysis of the 16S rRNA gene.     

Phosphate solubilization by Penicillium spp. isolated from soil samples of Indian Himalayan region

A total of 246 fungal isolates representing 36 genera and 72 species were isolated from the soil samples collected from Indian Himalayan region. Twenty-one species belonged to the genus Penicillium alone. All the Penicillium species were screened for phosphate solubilizing activity on Pikovskaya agar at 21 °C. Eight species of Penicillium, exhibiting formation of halos (zone of solubilization) around the fungal colonies in qualitative plate assays, were selected for quantitative estimations. In quantitative estimations that were conducted upto day 30 (at 3 days interval), seven species of Penicillium brought maximum solubilization after day 15, while P. oxalicum showed maximum solubilization after day 21 of incubation. The increase in solubilization coincided with decrease in pH of the broth. Acid phosphatase activity was 1.5–2.0 times higher in comparison to alkaline phosphatase. Many of these species showed wide range of tolerance for temperature, pH and salt concentration.     

23株不同地理来源嗜酸硫杆菌的系统发育及其遗传差异

【目的】研究不同地理来源嗜酸硫杆菌的系统发育及其遗传差异,以及基因指纹图谱技术聚类与嗜酸硫杆菌地理来源的相关性。【方法】采用16S-23S r RNA间隔区(ITS)序列建立系统发育树,并结合ERIC和BOXAIR两种引物进行rep-PCR,以及rus基因扩增,对不同地理来源嗜酸硫杆菌进行分析。【结果】分离自不同样点的23株嗜酸硫杆菌遗传差异显著,依据ITS序列系统发育树被划分为5个大类群,与rep-PCR指纹图谱的分类结果较为接近,其中Acidithiobacillus ferrooxidans在ITS系统发育和BOXAIR-PCR指纹聚类分析中被划分为2个类群,但在ERIC-PCR中归为1个类群,rus基因分组中,在系统发育和聚类分析中处于同一类群的菌株拥有不同类型的rus基因,说明嗜酸硫杆菌的亚铁氧化途径与系统发育类群无明显相关性;ITS基因拥有区分近缘种或亚种的能力,且BOXAIR-PCR的分辨能力较强,非常适于嗜酸硫杆菌的遗传差异分析。     

Decolorization of azo, triphenylmethane and anthraquinone dyes by a newly isolated Trametes sp. SQ01 and its laccase

A white-rot fungus, strain SQ01, was isolated from decayed wood in a temperate forest. The strain was identified as a member of genus Trametes, based on the morphological characteristics and a complete sequence analysis of its 18S rRNA gene and ITS region. Strain SQ01 was capable of decolorizing a variety of synthetic dyes, including azo, triphenylmethane, and anthraquinone dyes, with an optimal efficiency of decolorization obtained when dyes added after 5 days of culture, with the exception of Cresol Red, showing that the point of dye addition was an important influencing factor for decolorization by this fungus. All of the tested dyes were decolorized by the purified laccase in the absence of any redox mediators, but only a few were completely removed, while others were not completely degraded even with increased decolorization time.     

Diversity and evolution of 5S rRNA gene family organization in Pythium

The 5S rRNA gene family organization among 87 species and varieties of Pythium was investigated to assess evolutionary stability of the two patterns detected and to determine which pattern is likely the ancestral state in the genus. Species with filamentous sporangia (Groups A-C according to the ITS phylogenetic tree for Pythium) had 5S genes linked to the rDNA repeat that were predominantly coded for on the DNA strand opposite to the one with the other rRNA genes (‘inverted’ orientation). A small group of species with contiguous sporangia (Group D) is related to Groups A-C but had unlinked 5S genes. The main group of species with spherical zoosporangia (Groups E-J) generally had unlinked 5S genes in tandem arrays. The six species in Group K, although they also have spherical sporangia, had linked genes on the same strand as the other rRNA genes ‘non-inverted’ and most of them had pairs of tandem 5S genes. The evolutionary stability of 5S sequence organization was compared with the stability of morphological characters as interpreted from a phylogeny based on ITS sequence analysis. Features of 5S sequence organization were found to be just as consistent within groups as were the morphological characters. To determine the ancestral type of 5S family organization, a survey of Phytophthora strains was conducted to supply an outgroup reference. The most parsimonious interpretation of the data in this survey yielded the tentative conclusion that the linked condition of the 5S sequences was ancestral.     

Organic acid production and plant growth promotion as a function of phosphate solubilization by Acinetobacter rhizosphaerae strain BIHB 723 isolated from the cold deserts of the trans-Himalayas

An efficient phosphate-solubilizing plant growth–promoting Acinetobacter rhizosphaerae strain BIHB 723 exhibited significantly higher solubilization of tricalcium phosphate (TCP) than Udaipur rock phosphate (URP), Mussoorie rock phosphate (MRP) and North Carolina rock phosphate (NCRP). Qualitative and quantitative differences were discerned in the gluconic, oxalic, 2-keto gluconic, lactic, malic and formic acids during the solubilization of various inorganic phosphates by the strain. Gluconic acid was the main organic acid produced during phosphate solubilization. Formic acid production was restricted to TCP solubilization and oxalic acid production to the solubilization of MRP, URP and NCRP. A significant increase in plant height, shoot fresh weight, shoot dry weight, root length, root dry weight, and root, shoot and soil phosphorus (P) contents was recorded with the inoculated treatments over the uninoculated NP₀K or NP_TCPK treatments. Plant growth promotion as a function of phosphate solubilization suggested that the use of bacterial strain would be a beneficial addition to the agriculture practices in TCP-rich soils in reducing the application of phosphatic fertilizers.     

Characterization of a Chromobacterium haemolyticum population from a natural tropical lake

Aim: To study genetic diversity of Chromobacterium haemolyticum isolates recovered from a natural tropical lake. Methods and Results: A set of 31 isolates were recovered from a bacterial freshwater community by conventional plating methods and subjected to genetic and phenotypic characterization. The 16S ribosomal RNA (rRNA) gene phylogeny revealed that the isolates were related most closely with C. haemolyticum. In addition to the molecular data, our isolates exhibited strong β‐haemolytic activity, were nonviolacein producers and utilized i‐inositol, d ‐mannitol and d ‐sorbitol in contrast with the other known chromobacteria. Evaluation of the genetic diversity in the 16S rRNA gene, tRNA intergenic spacers (tDNA) and 16S‐23S internal transcribed spacers (ITS) unveiled different levels of genetic heterogeneity in the population, which were also observed with repetitive extragenic palindromic (rep)‐PCR genomic fingerprinting using the BOX‐AR1 primer. tDNA‐ and ITS‐PCR analyses were partially congruent with the 16S rRNA gene phylogeny. The isolates exhibited high resistance to β‐lactamic antibiotics. Conclusion: The population genetic heterogeneity was revealed by 16S rRNA gene sequence, ITS and BOX‐PCR analysis. Significance and Impact of the Study: This study provides for the first time an insight into the genetic diversity of phylogenetically close isolates to C. haemolyticum species.