Plant growth-promoting activity in newly isolated <Emphasis Type="Italic">Bacillus thioparus</Emphasis> (NII-0902) from Western <Emphasis Type="Italic">ghat</Emphasis> forest,India

A Gram-positive rod-shaped bacterium isolated on nutrient agar plates incubated at 28 ± 2°C. The identity of the bacterium was confirmed by sequencing of the 16S rRNA gene and it reveals that it shares highest similarity with Bacillus thioparus CECT 7196^T (99.08%). It was capable of growing at temperatures ranging from 4 to 40°C, but optimum growth was observed at 28 ± 2°C. Strain NII-0902 is endowed with multiple plant growth promotion attributes such as phosphate solubilization, Indole acetic acid (IAA), siderophore and HCN production, which were expressed differentially at sub-optimal temperatures (5–40°C). It was able to solubilize phosphate (17.7 μg ml⁻¹), and produce IAA (139.7 μg ml⁻¹) at 28 ± 2°C. Qualitative detection of siderophore production and HCN were also observed. At 5°C it was found to express all the plant growth promotion attributes except HCN production. The ability to colonize roots is a sine qua non condition for a rhizobacteria to be considered a true plant growth-promoting rhizobacteria (PGPR). Bacillus sp. NII-0902 has a potential ability to colonize roots visualized by transparency, bacterial growth (turbid, milky and narrow zone) along and around roots and truly supported by scanning electron micrograph. Hence, it is proposed that, Bacillus thioparus sp. NII-0902 could be deployed as an inoculant to attain the desired results of bacterization.     

Improvement in the growth performance of white shrimp, Litopenaeus vannamei, by a protease-producing probiotic, Bacillus subtilis E20, from natto

Aims:  To isolate and identify a benefic bacterium, Bacillus subtilis E20, from natto (fermented soybeans), and incorporate it into shrimp feed to promote shrimp growth performance.
Methods and Results:  A protease-producing bacterium, E20, isolated from natto was identified as B. subtilis by an API 50 CHB kit and the 16S rDNA sequence. B. subtilis E20 was able to grow at a broad range of temperatures (10–50°C), pH values (5–10), and NaCl levels (0–9%). The best culture conditions for B. subtilis E20 to produce the protease were 40°C, a pH of 6–8 and 0% NaCl. No shrimp died after being injected with B. subtilis E20 [up to 10⁹ colony-forming units (CFU) per shrimp]. Bacillus subtilis E20 was incorporated in diets at the levels of 0 (control), 10⁶, 10⁷, and 10⁸ CFU kg⁻¹ for shrimp grow-out culture, and results showed that after feeding on B. subtilis E20-containing diets (10⁸ CFU kg⁻¹ of diet), shrimp had excellent growth performance and production compared to the control because protease activities in the digestive tract were improved by B. subtilis E20.
Conclusions:  Bacillus subtilis E20 isolated from natto is a great protease producer and is able to improve shrimp growth performance through increasing the digestibility of food.
Significance and Impact of the Study:  Results suggest that B. subtilis E20 is a potential candidate for use as a probiotic to improve shrimp growth performance, and consequently reduce feed costs.     

Seasonal heterotrophic flagellate and bacterial plankton dynamics in a large oligotrophic lake– Loch Ness, Scotland

1. Bacterial production in the 0–30 m water column of Loch Ness was measured using a dual labelling procedure with [³H] thymidine and [¹⁴C] leucine between May 1993 and June 1994. In most cases the uptake of the two labels did not covary, suggesting unbalanced growth. Rates of bacterial production varied from undetectable to 46.2 μg C l^–1 day^–1. Highest production coincided with the period of highest primary production, but carbon derived from this source was insufficient to meet the bacterial carbon demand, which was met by allochthonous humic inputs to the system.
2. Heterotrophic flagellate (HNAN) grazing rates, measured using fluorescently labelled bacteria, ranged between 10.3 and 24.5 bacteria cell^–1 day^–1 at temperatures between 5 and 15 °C. They removed up to 27% of the bacterial production per day.
3. Heterotrophic flagellate specific growth rates ranged from 0.043 to 0.093 h^–1 between 5 and 15 °C, giving generation times of 7.4–16.1 h.
4. bacterial and HNAN abundances were not coupled, but the highest HNAN grazing impact related to a time of high bacterial productivity.     

Modelling the growth of Weissella cibaria as a function of fermentation conditions

Aims:  To investigate the effect of pH, water activity ( a _w) and temperature on the growth of Weissella cibaria DBPZ1006, a lactic acid bacterium isolated from sourdoughs.
Methods and Results:  The kinetics of growth of W. cibaria DBPZ1006 was investigated during batch fermentations as a function of pH (4·0–8·0), a _w (0·935–0·994) and temperature (10–45°C) in a rich medium. The growth curve parameters (lag time, growth rate and asymptote) were estimated using the dynamic model of Baranyi and Roberts (1994. A dynamic approach to predicting bacterial growth in food. Int J Food Microbiol 23, 277–294). The effect of pH, a _w and temperature on maximum specific growth rate (μ_max) were estimated by fitting a cardinal model. μ_max under optimal conditions (pH = 6·6, a _w = 0·994, T  = 36·3°C) was estimated to be 0·93 h⁻¹. Minimum and maximum estimated pH and temperature for growth were 3·6 and 8·15, and 9·0°C and 47·8°C, respectively, while minimum a _w was 0·918 (equivalent to 12·2% w/v NaCl).
Conclusions:  Weissella cibaria DBPZ1006 is a fast-growing heterofermentative strain, which could be used in a mixed starter culture for making bread.
Significance and Impact of the Study:  This is the first study reporting the modelling of the growth of W. cibaria , a species that is increasingly being used as a starter in sourdough and vegetable fermentations.     

Growth enhancement of black pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis>) by a newly isolated <Emphasis Type="Italic">Bacillus tequilensis</Emphasis> NII-0943

A Gram positive, rod-shaped potential strain was selected from the pool of bacterial isolates obtained from the Western Ghats forest (India) on the basis of zone of P-solubilization activity. Identification based on 16S rRNA gene sequence revealed that the strain is of Bacillus species, sharing highest sequence similarity to Bacillus tequilensis NRRL B-41771^T (99.5%). Strain NII-0943 was able to produce good amount of indole acetic acid (IAA) and was positive for siderophore production. In addition to IAA and siderophore attributes, strain NII-0943 also possessed the characteristics like Ca₃(PO₄)₂ solubilization and growth in nitrogen-free medium. Seed inoculation with the strain NII-0943 resulted in significantly higher root initiation in black pepper cuttings grown under pots. The contents of nitrogen and phosphorus in both soil and plant were also enhanced significantly in treatments inoculated with these bacterial inocula. Hence, based on this evidence it is proposed that strain NII-0943 could be deployed as a plant growth-promoting inoculant to attain the desired results of bacterization.     

Characterization of a cold-tolerant plant growth-promoting bacterium Pantoea dispersa 1A isolated from a sub-alpine soil in the North Western Indian Himalayas

Pantoea dispersa strain 1A is a Gram-negative rod-shaped, yellow-pigmented bacterium isolated on nutrient agar plates incubated at 4°C. The identity of the bacterium was confirmed by sequencing of the 16 S rRNA gene. It was capable of growing at temperatures ranging from 4 to 42°C, but maximum growth was observed at 30°C. It is endowed with multiple plant growth promotion attributes such as phosphate solubilization, IAA production, siderophore production and HCN production, which are expressed differentially at sub-optimal temperatures (15 and 4°C). It was able to solubilize phosphate (17.6 μg of P₂O₅ ml⁻¹ day⁻¹), and produce IAA (3.7 μg ml⁻¹ day⁻¹), at 15°C. Qualitative detection of siderophore production and HCN were also observed at 15°C. At 4°C it was found to express all the plant growth promotion attributes. This bacterial isolate was able to positively influence and promote the growth and nutrient uptake parameters of wheat (cv. VL.802) under glasshouse conditions. Hence in the context, of cold wheat-growing environments, it is proposed that Pantoea dispersa 1A (MTCC 8706), could be deployed as an inoculant to attain the desired results of bacterization.     

Sucrose phosphorylase of the rumen bacterium Pseudobutyrivibrio ruminis strain A

Aims:  To verify the taxonomic affiliation of bacterium Butyrivibrio fibrisolvens strain A from our collection and to characterize its enzyme(s) responsible for digestion of sucrose.
Methods and Results:  Comparison of the 16S rRNA gene of the bacterium with GenBank showed over 99% sequence identity to the species Pseudobutyrivibrio ruminis . Molecular filtration, native electrophoresis on polyacrylamide gel, zymography and thin layer chromatography were used to identify and characterize the relevant enzyme. An intracellular sucrose phosphorylase with an approximate molecular mass of 52 kDa exhibiting maximum activity at pH 6·0 and temperature 45°C was identified. The enzyme was of inducible character and catalysed the reversible conversion of sucrose to fructose and glucose-1-P. The reaction required inorganic phosphate. The K _m for glucose-1-P formation and fructose release were 3·88 × 10⁻³ and 5·56 × 10⁻³ mol l⁻¹ sucrose, respectively – while the V _max of the reactions were −0·579 and 0·9  μ mol mg protein⁻¹ min⁻¹. The enzyme also released free glucose from glucose phosphate.
Conclusion:  Pseudobutyrivibrio ruminis strain A utilized sucrose by phosphorolytic cleavage.
Significance and Impact of the Study:  Bacterium P. ruminis strain A probably participates in the transfer of energy from dietetary sucrose to the host animal.     

Life history and production of Paranephrops zealandicus in a forest stream, with comments about the sustainable harvest of a freshwater crayfish

1. Life history and production were assessed for the crayfish Paranephrops zealandicus in three reaches of a headwater stream with a catchment of regenerating coniferous-broadleaf forest in the south-east of the South Island of New Zealand.
2. Crayfish density ranged from 3 to 4 m⁻² in riffles and 4–12 m⁻² in pools, depending on reach. Crayfish biomass (4–33 g AFDW m⁻²) and annual production (2–11 g AFDW m⁻²) were high compared with values reported elsewhere, while P:B ratio was low (0.33–0.43). This substantial production was dependent primarily upon high biomass rather than high growth rate.
3. The crayfish of this population rank amongst the longest lived and slowest growing ever recorded. Individuals estimated to be 16+ year of age were not uncommon. Females became reproductively active at 6+ year. Fewer than 4% of females carried eggs, and young remained attached to females for at least 15 months.
4. We propose that characteristics of this population are the consequence of a cool thermal regime (mean daily stream temperature = 7.0 °C, range 1.8–11.9 °C), and that low biomass turnover and poor reproductive rate precludes any sustainable commercial harvest of crayfish from streams in New Zealand with similar thermal regimes.     

Isolation and characterization of alginate-degrading bacteria for disposal of seaweed wastes

Aims:  Isolation of novel alginate degrading bacteria for the disposal of seaweed waste in composting process.
Methods and Results:  Decomposition of alginate polymers was checked by the 3,5-dinitrosalicylic acid (DNS) method for reducing sugar, and absorbance at 235 nm for unsaturated sugar. A bacterium A7 was isolated from wakame compost and confirmed to belong to the genus Gracilibacillus by partial 16S rDNA analysis. The optimum condition for the growth of A7 in a medium containing 5 g l⁻¹ of sodium alginate is as follows: pH, 8·5–9·5; NaCl, 0·5 mol l⁻¹; temperature, 30°C and polypeptone as nutrient content, 2–5 g l⁻¹. In a laboratory-scale composting experiment, the alginate content in wakame compost decreased to 14·3% after 72 h of composting from an initial value of 36%, indicating the effectiveness of alginate decomposition of A7 in wakame composting.
Conclusions:  The bacterium A7 was found to be alginate lyase-producing in genus Gracilibacillus and effective in degrading alginate to oligosaccharides in wakame during composting process.
Significance and Impact of the Study:  Development of new methods for the disposal of marine wastes and production of functional products.     

Isolation and characterization of novel plant growth promoting Micrococcus sp NII-0909 and its interaction with cowpea

A phosphate-solubilizing bacterial strain NII-0909 isolated from the Western ghat forest soil in India was identified as Micrococcus sp on the basis of phenotypic characteristics, carbon source utilization pattern, fatty acid methyl esters analysis, and 16S rRNA gene sequence. The strain exhibited the plant growth-promoting attributes of phosphate solubilization, auxin production, 1-aminocyclopropane-1-carboxylate deaminase activity, and siderophore production. It was able to solubilize (122.4 μg of Ca₃PO₄ ml^?1), and produce IAA (109 μg ml^?1) at 30 °C. P-solubilizing activity of the strain NII-0909 was associated with the release of organic acids and a drop in the pH of the NBRIP medium. HPLC analysis detected two organic acids in the course of P-solubilization. A significant increase in the growth of cow pea was recorded for inoculations under controlled conditions. Scanning electron microscopic study revealed the root colonization of strain on cow pea seedlings. These results demonstrate that isolates NII-0909 has the promising PGPR attributes to be develop as a biofertilizer to enhance soil fertility and promote the plant growth.     

Potential plant growth-promoting activity of <Emphasis Type="Italic">Serratia nematodiphila</Emphasis> NII-0928 on black pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis> L.)

A potential bacterial strain designated as NII-0928 isolated from Western ghat forest soil with multiple plant growth promoting attributes, and it has been identified and characterized. Plant growth promoting traits were analyzed by determining the P-solubilization efficiency, Indole acetic acid production, HCN, siderophore production and growth in nitrogen free medium. It was able to solubilize phosphate (76.6 μg ml⁻¹), and produce indole acetic acid (58.9 μg ml⁻¹) at 28 ± 2°C. Qualitative detection of siderophore production and HCN were also observed. At 5°C it was found to express all the plant growth promotion attributes except HCN production. The ability to colonize roots is a sine qua non condition for a rhizobacteria to be considered a true plant growth-promoting rhizobacteria (PGPR). 16S rRNA gene sequencing reveals the identity of the isolate as Serratia nematodiphila with which it shares highest sequence similarity (99.4%). Seed bacterization with black pepper cuttings in greenhouse trials using Sand: Soil: FYM with three individual experimental sets with their respective control showed clearly the growth promoting activity. Hence, Serratia nematodiphila NII-0928 is a promising plant growth promoting isolate showing multiple PGPR attributes that can significantly influence black pepper cuttings. The result of this study provides a strong basis for further development of this strain as a bioinoculants to attain the desired plant growth promoting activity in black pepper growing fields.     

Effect of Temperature on the Formation of Microsclerotia of Verticillium dahliae

Microsclerotium formation by six isolates of Verticillium dahliae was studied at different temperatures both in vitro and in Arabidopsis thaliana . In vitro mycelial growth was optimal at 25°C, but microsclerotium formation was greatest at 20°C (two isolates) or 15–20°C (one isolate). Seedlings of A. thaliana were root-dipped in a conidial suspension, planted, and either placed at 5, 10, 15, or 25°C, or left at 20°C until the onset of senescence, after which some of the plants were placed at 5, 10, 15, or 25°C. The amount of microsclerotia per unit of shoot weight was assessed in relation to isolate and temperature. The optimal temperature for production of microsclerotia was 15–25°C. Two isolates each produced about 10 times more microsclerotia than each of the other four isolates. For these isolates, high R ²_adj.-values of 0.77 and 0.66 were obtained, with temperature and its square as highly significant (P   < 0.001) independent variables. R ²_adj.-values for the other isolates varied between 0.28 and 0.39. Moving plants to different temperatures at the onset of senescence led to microsclerotial densities that were intermediate between densities on plants that had grown at constantly 20°C and plants grown at other temperatures. This suggests that vascular colonization rate and rate of microsclerotium formation are similarly affected by temperature. The senescence rate of plants appeared unimportant except for plants grown at 25°C, which showed the highest amounts of microsclerotia per unit of plant weight in the most rapidly senescing plants.     

Sanitation of faeces from source-separating dry toilets using urea

Aim:  To develop a reliable and simple method to produce safe fertilizers from human excreta using urea for sanitation of faeces.
Methods and Results:  Urea was added to faecal matter (17% dry matter) at concentrations of 0·5–2% (w/w) and inactivation of Salmonella enterica subspecies 1 serovar Typhimurium (Salm. Typhimurium), Enterococcus spp . and the Salm. Typhimurium bacteriophage 28B was monitored at 14, 24 and 34°C. Urea additions enhanced inactivation and inactivation rates were positively related to increasing NH₃ (aq) concentration and temperature. Salm. Typhimurium was the most sensitive of the organisms studied, while Enterococcus spp. showed more persistence, especially at lower temperatures. The bacteriophage was the most resistant organism studied.
Conclusions:  Salmonella reduction levels that meet requirements for safe reuse of faeces as fertilizer (i.e. 6 log₁₀ reduction) can be achieved for 1% urea within 2 months at 14°C or within 1 week at 24°C and 34°C.
Significance and Impact of the Study:  The relationships between organism inactivation rates and temperature, ammonia and pH were identified. Urea treatment proved to be a robust and efficient option for safe recycling of plant nutrients.     

A thermotolerant and high acetic acid-producing bacterium Acetobacter sp. I14–2

A thermotolerant bacterium with high production of acetic acid was isolated from spoiled banana in Taiwan. The isolate, I14–2 ,was considered to be an Acetobacter sp. according to phenotypic and chemotaxonomic characteristics. Optimal cultural conditions for Acetobacter sp. I14–2 to produce acetic acid were studied under cultivation in a medium containing 2 mg l⁻¹ acetic acid and 5% ethanol at 30 °C. Acetic acid productivity by Acetobacter sp. I14–2 was almost two and three times the amount produced by Acet. aceti IFO3283 and Acetobacter sp. CCRC 12326, respectively. The isolate retained 22% residual acetic acid-producing activity after 3 d incubation in a medium containing 8% ethanol, and produced acetic acid in a medium containing 10 g l⁻¹ acetic acid. This bacterium is thermotolerant and retained 97% and 68% of acetic acid-producing activity after 3 d incubation at 35 °C and 37 °C, respectively, compared with that when incubated at 30 °C.     

Isolation and characterization of Halomonas sp. strain C2SS100, a hydrocarbon-degrading bacterium under hypersaline conditions

Aims:  To isolate and characterize an efficient hydrocarbon-degrading bacterium under hypersaline conditions, from a Tunisian off-shore oil field.
Methods and Results:  Production water collected from 'Sercina' petroleum reservoir, located near the Kerkennah island, Tunisia, was used for the screening of halotolerant or halophilic bacteria able to degrade crude oil. Bacterial strain C2SS100 was isolated after enrichment on crude oil, in the presence of 100 g l⁻¹ NaCl and at 37°C. This strain was aerobic, Gram-negative, rod-shaped, motile, oxidase + and catalase +. Phenotypic characters and phylogenetic analysis based on the 16S rRNA gene of the isolate C2SS100 showed that it was related to members of the Halomonas genus. The degradation of several compounds present in crude oil was confirmed by GC–MS analysis. The use of refined petroleum products such as diesel fuel and lubricating oil as sole carbon source, under the same conditions of temperature and salinity, showed that significant amounts of these heterogenic compounds could be degraded. Strain C2SS100 was able to degrade hexadecane (C₁₆). During growth on hexadecane, cells surface hydrophobicity and emulsifying activity increased indicating the production of biosurfactant by strain C2SS100.
Conclusions:  A halotolerant bacterial strain Halomonas sp. C2SS100 was isolated from production water of an oil field, after enrichment on crude oil. This strain is able to degrade hydrocarbons efficiently. The mode of hydrocarbon uptake is realized by the production of a biosurfactant which enhances the solubility of hydrocarbons and renders them more accessible for biodegradation.
Significance and Impact of the Study:  The biodegradation potential of the Halomonas sp. strain C2SS100 gives it an advantage for possibly application on bioremediation of water, hydrocarbon-contaminated sites under high-salinity level.     

Production of tylosin in solid-state fermentation by Streptomyces fradiae NRRL-2702 and its gamma-irradiated mutant (γ-1)

Aims:  To develop solid-state fermentation system (SSF) for hyper production of tylosin from a mutant γ-1 of Streptomyces fradiae NRRL-2702 and its parent strain.
Methods and Results:  Various agro-industrial wastes were screened to study their effect on tylosin production in SSF. Wheat bran as solid substrate gave the highest production of 2500 μg of tylosin g⁻¹ substrate by mutant γ-1 against parent strain (300 μg tylosin g⁻¹ substrate). The tylosin yield was further improved to 4500 μg g⁻¹ substrate [70% moisture, 10% inoculum (v/w), pH 9·2, 30°C, supplemental lactose and sodium glutamate on day 9]. Wild-type strain displayed less production of tylosin (655 μg of tylosin g⁻¹ substrate) in SSF even after optimization of process parameters.
Conclusion:  The study has shown that solid-state fermentation system significantly enhanced the tylosin yield by mutant γ-1.
Significance and Impact of the Study:  This study proved to be very useful and resulted in 6·87 ± 0·30-fold increase in tylosin yield by this mutant when compared to that of wild-type strain.     

Characterization of a novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39

Aims:  The aims of this study were to identify and characterize the novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39.
Methods and Results:  Strain B39 was closely related to Paenibacillus cookii in 16S rRNA gene sequence. Nonetheless, this isolate can be identified as a novel Paenibacillus sp. with respect to its physiological characteristics, biochemical reactions, and profiles of fatty acid compositions. A cellulase with both CMCase and avicelase activities was secreted from strain B39 and purified by ion-exchange chromatography. By sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis, the molecular weight of B39 cellulase was determined as 148 kDa, which was much higher than other cellulases currently reported from Paenibacillus species. The enzyme showed a maximum CMCase activity at 60°C and pH 6·5. Addition of 1 mmol l⁻¹ of Ca²⁺ markedly enhanced both CMCase and avicelase activities of the enzyme.
Conclusions:  We have identified and characterized a novel thermophilic Paenibacillus sp. strain B39 which produced a high-molecular weight cellulase with both CMCase and avicelase activities.
Significance and Impact of the Study:  Based on the ability to hydrolyse CMC and avicel, the cellulase produced by Paenibacillus sp. strain B39 would have potential applications in cellulose biodegradation.     

Bovicin HC5 reduces thermal resistance of Alicyclobacillus acidoterrestris in acidic mango pulp

Aims:  To test the effect of bovicin HC5 against vegetative cells and endospores of Alicyclobacillus acidoterrestris DSMZ 2498 in synthetic media and in acidic mango pulp.
Methods and Results:  Alicyclobacillus acidoterrestris was grown in synthetic medium at 40°C and pH 4·0. The effect on vegetative cells was assayed by adding bovicin HC5 to synthetic medium (40–160 AU ml⁻¹) or to mango pulp (100 AU ml⁻¹) at various pH values and determining the effect on growth (OD_600nm) and viable cell number, respectively. The effect of bovicin HC5 on spore germination and thermal sensitivity of A. acidoterrestris was tested in mango pulp (pH 4·0) containing 80 AU ml⁻¹ of bovicin HC5. Bovicin HC5 was bactericidal against vegetative cells of A. acidoterrestris at different pH values and showed sporicidal activity against endospores of this bacterium. When spores of A. acidoterrestris were heat treated in the presence of bovicin HC5, D -values decreased 77% to 95% compared to untreated controls at temperatures ranging from 80 to 95°C.
Conclusion:  Bovicin HC5 was bactericidal and sporicidal against A. acidoterrestrsi DSMZ 2498.
Significance and Impact of the Study:  These results indicated that bovicin HC5 has potential to prevent spoilage of acidic fruit juices by thermocidophilic spore-forming bacteria.     

Characterization of plant growth-promoting rhizobacterium <Emphasis Type="Italic">Exiguobacterium</Emphasis> NII-0906 for its growth promotion of cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis>)

A phosphate solubilizing and antagonistic bacterial strain, isolated from a Western Ghat forest soil in Kerala province, India (designated as NII-0906), showed cold tolerance and grew from 10 to 37°C (optimum temperature 30°C). It was a Gram-positive, rod shaped, 0.8–1.6 μm in size, and exhibited tolerance to a wide pH range (5–12; optimum 7.0) and salt concentration up to 7% (w/v). The isolate showed maximum similarity with Exiguobacterium marinum TF-80^T based on 16S rRNA analysis. It solubilized tricalcium phosphate under in vitro conditions. The phosphate solubilization was estimated along a temperature range (5–40°C), and maximum activity (84.7 μg mL⁻¹ day⁻¹) was recorded at 30°C after 10 days of incubation. The phosphate solubilizing activity coincided with a concomitant decrease in pH of the medium. The isolate also exhibited antifungal activity against phytopathogenic fungi in Petri dish assays and produced siderophore and hydrogen cyanide. The strain’s plant growth promotion properties were demonstrated through a cowpea-based bioassay under greenhouse conditions. The bacterial inoculation resulted in significant increment in plant root, stem and as well as in plant biomass. Further, scanning electron microscopic study revealed the root colonization in cowpea. These results could offer potential perspective for the strain to be used as plant growth-promoting rhizobacteria, which could be used as an inoculant for regional crops.     

3-Methylindole production is regulated in Clostridium scatologenes ATCC 25775

Aims:  3-Methylindole (3-MI) is a degradation product of l -tryptophan and is both an animal waste malodorant and threat to ruminant health. Culture conditions influencing 3-MI production in Clostridium scatologenes ATCC 25775 were investigated.
Methods and Results:  Extracellular 3-MI levels in cells cultured in brain heart infusion (BHI) medium (pH 7·0) at 33°C and 37°C for 72 h were 907 ± 38 and 834 ± 121  μ mol l⁻¹, respectively. Cells cultured in tryptone-yeast (TY) extract medium at 37°C for 48 h produced 104 ± 86  μ mol l⁻¹ 3-MI; however, addition of 1 mmol l⁻¹  l -tryptophan failed to increase extracellular levels (113 ± 50  μ mol l⁻¹ 3-MI). Specific activity of indole acetic acid decarboxylase measured in BHI, TY and TY plus 1 mmol l⁻¹ tryptophan-grown cells displayed 35-, 33- and 76-fold higher levels than in semi-defined medium-grown cells.
Conclusions:  When cultured in rich medium, at 33°C or 37°C and pH 7·0, Cl. scatologenes ATCC 25775 optimally produced 3-MI. Addition of l- tryptophan to medium did not lead to significant increases in extracellular 3-MI levels. Whole cell assays indicate growth in rich medium significantly up-regulated 3-MI production.
Significance and Impact of the Study:  Information presented here may prove useful in understanding what factors influence 3-MI production in malodorous animal wastes.