Azotobacter Sp Research Articles

The potency of bio-organic fertilizer containing local microorganism of Cibodas village, Lembang-West Java

This experiment was conducted to determine the characteristics of biofertilizers usually called as Local Microorganism (LM) with the raw materials that is easily obtained in the village of Cibodas Lembang. This experiment included ten main raw materials as media for growing LM, including: Bamboo Root, Spring Onion, Broccoli Leaves, Banana Stump, Leaves of Water Hyacinth, Goat Manure, Rabbit Manure, Chicken Manure, Cow Manure and Rabbit Urine. The LM was enriched with material sugar and carbohydrates then incubated for 2 weeks. Parameters observed in the laboratory include IAA hormones, cytokines and gibberellins. The microorganism living in the LM i.e Total microorganism (Total Plate Count Aerob), Azospirillium, Azotobacter and Trichoderma were also analysed. The results showed that the LM with raw materials from chicken manure showed the highest hormone content in both IAA, Cytokinin (Zeatin), Cytokinin (Kinetin) and Giberelin with the following values: 141.28 ppm, 115.63 ppm, 126.49 ppm, 165.13 ppm, respectively. The same LM showed highest number of microorganisms based on TPC method and Trichoderma with a value of 3.75 x 108, 6.80 x 105 CFU/ml. As for the analysis of the LM goat manure contain the highest number of Azospirillium which population of 2.4 x 105 CFU/ml and the highest population of Azotobacter sp was found in LM of rabbit manure with a value of 6.95 x 103 CFU / ml.

THE EFFECT OF ADDITIVE COMBINATION AND Azotobacter sp. TOWARDS Glycine max. L. GROWTH

This study was aimed at determining the increasing of growth and production of soybean crops by giving Azotobacter sp. and additive materials such as coconut water, molasses, and bran. This research was conducted on Januari 2018 to April 2018 at Ciparanje Experimental Field Faculty of Agriculture. Universitas Padjadjaran, Jatinangor, Sumedang, West Java Province, on ± 774 meters above sea level (asl) using single factor randomized block design with 10 treatments; Azotobacter sp. and additive materials combination such as coconut water, molasses, and bran in three repetitions. The observations on the parameters observed in the final vegetative phase were on plant height, chlorophyll content, and population of Azotobacter sp. using Total Plate Count (TPC) method.The results show that the application of combination additives materials and Azotobacter sp. effect on populations Azotobacter sp., chlorophyll content, plant height and number of soybean pods (Glycine max L.). Application of coconut water independently, water added with Azotobacter sp., and combination of additive with Azotobacter sp. can give the best effect to the content of chlorophyll, plant height, and soybean crops components (Glycine max. L.).PENGARUH KOMBINASI BAHAN ADITIF DAN Azotobacter sp. TERHADAP PERTUMBUHAN Glycine max. L.Penelitian ini bertujuan untuk mengetahui pertumbuhan dan produksi tanaman kedelai dengan memberikan Azotobacter sp. dan aditif air kelapa, molase, serta dedak. Penelitian ini dilaksanakan pada Januari 2018-April 2018 di Kebun Percobaan Ciparanje Fakultas Pertanian Universitas Padjadjaran, Jawa Barat pada ± 774 meter di atas permukaan laut (dpl). Penelitian ini menggunakan rancangan acak kelompok dengan 10 perlakuan pemberian Azotobacter sp. dan aditif air kelapa, molase, serta dedak dengan tiga ulangan. Pengamatan terhadap parameter yang diamati pada fase vegetatif akhir yaitu tinggi tanaman, kandungan klorofil, dan populasi Azotobacter sp. dengan metode Total Plate Count (TPC). Hasil penelitian menunjukkan aplikasi kombinasi bahan aditif dan penambahan pupuk hayati Azotobacter sp. berpengaruh terhadap populasi Azotobacter sp., kadar klorofil, tinggi tanaman dan jumlah polong tanaman kedelai (Glycine max L.). Aplikasi air kelapa secara mandiri, air kelapa yang ditambahkan dengan Azotobacter sp., dan kombinasi bahan aditif dengan Azotobacter sp. dapat memberikan pengaruh terbaik terhadap kandungan klorofil, tinggi tanaman, dan komponen hasil tanaman kedelai (Glycine max. L.).

Biocontrol del marchitamiento vascular del frijol, causado por Fusarium oxysporum empleando Rizobacterias Promotoras del Crecimiento Vegetal (PGPR).

La marchitez vascular causada por Fusarium oxysporum en Phaseolus vulgaris (frijol común) es un problema fitosanitario que afecta directamente al rendimiento y economía de los agricultores, para su control se usan productos químicos de contacto; sin embargo, una alternativa a este uso es el biocontrol, empleando organismos promotores de crecimiento vegetal (PGPR) con buena capacidad antagónica. En este trabajo se comparó géneros bacterianos con características PGPR; Bacillus (Bacillus sp. “a”, Bacillus sp. “b”, Rhizobium (CIAT 899), Actinobacteria (Streptomyces sp.), Prochloraz como control químico y los formulados con Azotobacter sp., y Bacillus subtilis como controles positivos. Se presentaron como mejores candidatos a PGPR y biocontroladores las cepas de Bacillus“a” y Actinobacteria, con una severidad de 1 y 3 grados, incidencia antagónica de 61.54 y 76.93%, peso seco de 0.42 y 0.31g y una longitud total de 17.23 y18 cm, respectivamente. El objetivo de este trabajo fue evaluar el biocontrol frente a F. oxysporum generado por bacterias tipo PGPR.

Compost inoculated with Azotobacter sp: impact assessment on eggplant (Solanum melongena) productivity and soil nutrient status in Ghana

ABSTRACTWe assessed the influence of Azotobacter inoculated commercial compost on eggplant productivity and soil nutrient status in the semi-deciduous forest zone of Ghana. In randomized complete block design, eight treatments (Control, 2.5 t ha−1 compost, 5 t ha−1 compost, 100% recommended NPK fertilizer at 50 kg N, 30 kg ha−1 P2O5 and 30 kg ha−1 K2O, 2.5 t ha−1 compost+50% NPK, 5 t ha−1 compost+50% NPK, 50% NPK and 2.5 t ha−1 compost+100% NPK) were evaluated under field conditions during two cropping seasons. In the major season, fruit yield under 5 t ha−1 compost significantly outperformed 50% and 100% NPK and the control. The highest fruit yield (4480 kg ha−1) was obtained under 5 t ha−1 compost in the minor season. While the effect of sole compost was significant on fruit yield, there were also strong trends suggesting added benefits from 2.5 t ha−1 compost+100% NPK. Integrated use of compost and NPK increased shoot biomass over the control and NPK treatments. The compost had significant effect (p < 0.05) on lowering soil pH at the end of study. The highest soil exchangeable Ca and Mg were recorded under sole compost. The findings suggest good prospect for increasing crop yield through inoculating compost with Azotobacter.

PARTIAL STUDY OF NON SYMBOTIC NITROGEN FIXING BACTERIA FROM RHIZOSFER OF GAMAL AS PLANT GROWTH PROMOITING ON THE LAND OF THREE STRATA SYSTEMS

Gamal is one of the tropical forages that can still grow and produce f on dry land in the hot season, while other plants, especially the grass has dried so it needs to be examined soil conditions in the rhizosphere. A study aimed at studying soil conditions in rhizosphere of gamal plants and obtaining isolates of non symbiotic nitrogen-fixing bacteria from gamal rhizosphere that function as Plant Growth Promoting on three strata land (STS) Pecatu, Bukit jimbaran, Badung, Bali. The research begins with observation of soil texture and color, soil structure determination and water content, pH, and soil total plate count, followed by calculation of non-symbiotic N fixing bacteria,, isolation, gram staining test, fermnetatif test, and catalase test. The results showed that soil characteristics of STS Pecatu land include clay clay texture, compact structure, brownish color, pH 6.79-7.40, water content 14,19-18,12, STS Pecatu land including fertile land with total plate count 1.65x 107 cfu/g, and 6 non-symbiotic non-beneficial bacterial inhibitors were suspected from the genus Azotobacter sp, with colonies of 83 x 105 cfu/g. Based on the result of the research, it can be concluded that the soil of STS Pecatu land including fertile land with total plate count 16,5 x 106 cfu/g, and found 6 isolate of non-symbiotic N fixing bacteria from genus Azotobacter sp, with number of colony 83 x 105 cfu/g.&#x0D; Keywords: Non-symbiotic N-fixing bacteria, Three-Strata System, Pecatu

English

English

NITROGEN FIXING BACTERIA AZOTOBACTER AS BIOFERTILIZER AND BIOCONTROL IN LONG BEAN

Azotobacter is Plant Growth Promoting Rhizobacteria through the mechanism of nitrogen fixation and phytohormon production but this rhizobacteria has a role to control plant diseases. The objective of experiment was to evaluate the activity of Azotobacter as biofertilizers as well as biocontrol on long bean cultivation in damping off endemic land in Ambon city, Maluku Province. The field experiment was arranged in completely randomized block design. Inoculation of long bean by Azotobacter has been done by seed inoculation, soil inoculation before planting, and plant inoculation. Plants treated with Azotobacter received fertilizer NPK of ¾ or ½ dosage recommendation while control plants were received 100% NPK. Research showed that no differences between yield of long bean inoculated with Azotobacter sp +reduced doses of NPK with that of control plants. Any application method of Azotobacter inoculation lowered damping off diseases incidence significantly until 10 days after planting, but no effect of inoculation on late blight at 21 days after planting. This study confirmed that Azotobacter has dual activity to reduce the dose of NPK fertilizer and control damping off.

KEMAMPUAN Azetobacter sp. DALAM MENINGKATKAN EFISIENSI PEMUPUKAN UREA PADA TANAMAN JAGUNG (Zea mays L.)

Azotobacter sp. is a non-symbiotic bacteria that has the ability to mobilize nitrogen from a form that is not available in a form that is available for plants. Inoculation of Azotobacter sp. into the planting medium can be used as a supplier of nitrogen required by the plant. Utilization of Azotobacter sp. as biofertilizer has the ability to minimize the use of chemical fertilizers, improve the soil fertility and increase the microbial activity in the rhizosphere of plants. Inoculation of Azotobacter sp. into the planting medium is one alternative to improve the efficiency of urea fertilizer in the maize cultivation. The result of this research showed that the application of Azotobacter sp. with the dose of 10 ml l-1 and 20 ml l-1 on the urea fertilization with the dose of 150 kg ha-1 were able to increase the growth of maize, so that maize has growth that was not significantly different with the maize that got urea with the dose of 225 kg ha-1 and 300 kg ha-1. Inoculation of Azotobacter sp. in the planting media, either with the dose of 10 ml l-1or 20 ml l-1were able to increase the maize yield when compared to the treatment without Azotobacter sp. Inoculation of Azotobacter sp. into the planting medium was able to increase the maize yield. However, increasing the dose of Azotobacter sp. more than 10 ml l-1 did not affect to increase the maize yield. Maize yield reached the optimum value when the dose of urea supplied was153.50 kg ha-1.

Influence of Soil pH on Azotobacter Population With Using Microbiological Characteristics as Bio-Measurement in Arable Lands of Tripoli. N. W. Libya

In the present study, 15 samples of soil were collected to isolate Azotobacter from the rhizosphere in different regions of Tripoli. LG specified medium was used for the isolation of bacteria and were purified on the same medium for identification and characterisation.The colonies were identified through microscopical and biochemical tests and the results obtained were classified as Azotobacter sp. Subsequently, the microbial population was calculated by colony count method. The soil pH, total nitrogen content (N), total phosphorus content (P) and organic carbon (OC) in soil were determined. The results of this study indicated to effects positive and negative of soil pH levels on Azotobacter population. In the estimation of above chemical properties of all soil samples it was showed that bacterial population differs significantly among the different soil samples.

Role of Bioinoculants for Improving Growth and Yield of Okra (Abelmoshuses culentum)

Elevated use of agrochemicals has been the backbone of sustainable crop production. However, the environmental hazards, soaring cost and stagnant production are the foremost issues affiliated with them. Exploitation of stumpy cost and environment friendly plant growth promoting rhizobacteria (PGPR) has certain encouraging results regarding sustainability in agricultural production. A glass house study was conducted at Soil Bacteriology Section, Ayub Agricultural Research Institute, Faisalabad to check the efficacy of different PGPR for growth and yield of okra (Abelmoshuses culentum). Treatments were control, Azotobacter sp inoculation, Azospirillum sp inoculation, Bacillus sp inoculation, Pseudomonas sp inoculation and Rhizobium sp inoculation. Results revealed that there was significant effect of all inoculants on growth and yield of okra crop. An increase of 23.5% and 21.0% in green pod yield was recorded with Pseudomonas sp and Bacillus sp, respectively. Positive consequence was observed in all other parameters where Pseudomonas inoculation was applied as compared to no inoculation. This study suggests that PGPR may be a dynamic biofertilizer to boost the yield of okra and other agricultural crops.

KEBERADAAN BAKTERI PELARUT FOSFAT DAN AKTIVITAS ENZIM FOSFATASE TANAH DAERAH PERAKARAN TANAMAN OBAT DARI KEBUN RAYA CIBODAS

A study was undertaken to investigate to occurance of phosphate solubilizing bacteria from rhizosphere soil samples of medicine plants in Cibodas Botanical Garden. 13 soil samples of medicine plants are collected randomly The result shows that 71 isolates of phosphate solubilizing bacteria were isolated, and 10 species of these organism was identified as Azotobacter sp, Bacillus sp, Chromobacterium sp, C.violaceum, Citrobacter sp. , Enterobacter sp., E. liquefaciens. Nitrosomonas sp., Serratia rubidaea, Sphaerotillus natans. Azotobacter sp. And Bacillus sp. Are found in all of soil tested. Conversely, Serratia rubidaea is only in the sample from rhizosphere of Plantago mayor The activity of acid alkaline phosphatase in soil tested ranged from 0.78 – 60,18 ugp nitrophenole/g/h, with the higest values being recorded in soil sample from rhizosphere of “Lavender”.Keywords : phosphate solubilizing bacteria, soil enzyme phosphatase

Desempenho agronômico da batata (Solanum tuberosum L.) cv. ´Unica´ sob inoculação com rhizobacterias nativas e aplicação de ácido acetil salicílico

Peru is center of origin of potato and its wild relatives, so it is convenient to develop new technologies of agronomical management with less impact on the ecosystem, as in the use of pesticides and chemical fertilizers in potato is increasing in developing countries. The objective of the work was to evaluate the agronomic performance of potato cv. ´Unica´ under inoculation with PGPR rhizobacteria isolated from the rhizosphere of Andean potatoes and on the effect of the application of acetylsalicylic acid in field conditions of the Peruvian coast. Inoculation of four bacterial isolates were evaluated: Bacillus simplex B13, Bacillus amyloliquefaciens Bac 15Mb, Azotobacter sp. Azo 16M2 and Pantoea sp. DZ22, as well as a dose of 0.4 mM acetyl salicylic acid as promoter treatments for plant growth versus a control with no inoculation. A randomized complete block design was used in a sandy loam class soil, slightly alkaline, with low organic content and free of salts. There was a relative humidity between 54 and 71%, while the average air temperatures ranged between 13 and 21 °C in San Vicente de Canete, Lima (coordinates UTM 18L3540788550372). Inoculated plants with bacterial strains at sowing time and control were evaluated at flowering in plots of 40 plants with three replications for several physiological and productive parameters. Means were separated statistically through Duncan's multiple range test and processed with Infostat software. Inoculation with strain Azotobacter sp. Azo 16M2, showed significant differences (p<0.05) with respect to control without inoculation, increasing tuber yield and commercial tuber weight per hectare and with less damage by the leafminer fly (Liriomyza huidobrensis) vis-a-vis the control. Also application of acetyl salicylic acid showed higher percentage of inflorescences (p<0.05) compared to the control, while statistical differences were not found between bacterial strains for this character. It was concluded that the application of inoculant strain Azotobacter sp. Azo 16M2 improved the agronomic performance of potato cv. ‘Unica’, under subtropical conditions of the valley of Canete in terms of production of tubers and commercial quality, and less foliage damage by the leafminer fly compared to non-inoculated plants.

Perubahan Kadar N Tersedia Dan Populasi Azotobacter Di Rizosfer Sorgum (Sorghum bicolor L.) Yang Ditanam Di Dua Ordo Tanah Dengan Inokulasi Azotobacter sp.

Bioagumentation by used of nonsimbiotic N­2 fixing Azotobacter is a way to enhance soil N availability in sustainable Agricultural land. A green house experiment has been done to verify effect of Azotobacter sp. inoculation in two soil order, Inceptisols and Entisols, on NH4+danNO3- content , N uptake as well as Azotobacter population in rhizosphere soil of sorghum (Sorghum bicolor L.). Experiment was set up in Randomized Block Design with eight treatments and three replicates, sorghum was maintained in green house until maximum vegetative phase. Resuls showed that Azotobacter sp. AS4 was more enable to increase the availability of soil N rather than isolate AS3. Bacterial bioaugmentation with Azotobacter sp. AS4 on Inceptisols increased more NO3-, Azotobacter sp. population in soil rhizosphere and shoot height of sorghum genotype 2.24.

Desempenho agronômico da batata (Solanum tuberosum L.) cv. ´Unica´ sob inoculação com rhizobacterias nativas e aplicação de ácido acetil salicílico

Peru is center of origin of potato and its wild relatives, so it is convenient to develop new technologies of agronomical management with less impact on the ecosystem, as in the use of pesticides and chemical fertilizers in potato is increasing in developing countries. The objective of the work was to evaluate the agronomic performance of potato cv. ´Unica´ under inoculation with PGPR rhizobacteria isolated from the rhizosphere of Andean potatoes and on the effect of the application of acetylsalicylic acid in field conditions of the Peruvian coast. Inoculation of four bacterial isolates were evaluated: Bacillus simplex B13, Bacillus amyloliquefaciens Bac 15Mb, Azotobacter sp. Azo 16M2 and Pantoea sp. DZ22, as well as a dose of 0.4 mM acetyl salicylic acid as promoter treatments for plant growth versus a control with no inoculation. A randomized complete block design was used in a sandy loam class soil, slightly alkaline, with low organic content and free of salts. There was a relative humidity between 54 and 71%, while the average air temperatures ranged between 13 and 21 °C in San Vicente de Cañete, Lima (coordinates UTM 18L3540788550372). Inoculated plants with bacterial strains at sowing time and control were evaluated at flowering in plots of 40 plants with three replications for several physiological and productive parameters. Means were separated statistically through Duncan's multiple range test and processed with Infostat software. Inoculation with strain Azotobacter sp. Azo 16M2, showed significant differences (p&lt;0.05) with respect to control without inoculation, increasing tuber yield and commercial tuber weight per hectare and with less damage by the leafminer fly (Liriomyza huidobrensis) vis-à-vis the control. Also application of acetyl salicylic acid showed higher percentage of inflorescences (p&lt;0.05) compared to the control, while statistical differences were not found between bacterial strains for this character. It was concluded that the application of inoculant strain Azotobacter sp. Azo 16M2 improved the agronomic performance of potato cv. ‘Unica’, under subtropical conditions of the valley of Cañete in terms of production of tubers and commercial quality, and less foliage damage by the leafminer fly compared to non-inoculated plants.

Effect of Azotobacter sp. and N Fertilizer on the Growth of Oil Palm Seedling Inoculated with Ganoderma sp.

Excess application of nitrogen fertilizer causes soil nutrient imbalances and reduce the number and soil microbial diversity. This condition could induce soil born dieseses such basal stem rot caused by Ganoderma sp. A study was conducted to enhance the plant tolerance to Ganoderma sp. through introduction of microbial community especially non-symbiotic N fxing bacteria, Azotobacter sp. Plant materials used were 4 months old of germinated oil palms, while Ganoderma sp. was isolated from Bekri, Lampung. There are seven treatments tested i e Azotobacter sp. + Ganoderma sp. (+A+G), Azotobacter sp. + 30% N fertilizer of recommended dosage + Ganoderma sp. (+A+30N+G), Azotobacter sp. + 60% N fertilizer of recommended dosage + Ganoderma sp. (+A+60N+G), Azotobacter sp. + 100% N fertilizer of recommended dosage + Ganoderma sp. (+A+100N+G), 100% N fertilizer of recommended dosage + Ganoderma sp. (+100N+G), Ganoderma sp. inoculation (positive control, +G), and non-inoculated Ganoderma sp. (negative control, -G). The result showed that Azotobacter sp.enhanced the height of plant inoculated with Ganoderma sp. when accompanied with N fertilizer of 30 to 100% of recommended dose. Moreover, +A+100N+G seedling had signifcantly higher fresh and dry weight of shoot compared to those of +G seedling or +100N+G seedling

Efekat različitih načina korišćenja zemljišta na mikrobiološka svojstva zemljišta Centralne Srbije

Aim of the study was to examine the effects of soil use on soil microbial properties at five locations in Central Serbia. The study included 42 samples of soil under certified organic system, 8 samples under conventional system, and 30 samples of abandoned soils. The number of examined microbial groups was assessed using the indirect dilution method followed by plating of soil suspension on different selective media, while dehydrogenase activity was measured spectrophotometrically. The number and activity of microorganisms at the tested plots primarily depended on the soil pH. The acidic soil reaction caused more rapid fungal growth and lower presence of actinomycetes and Azotobacter sp. There were no significant alterations in the number of microorganisms, ammonifiers and fungi under the specific soil use system. Significantly higher dehydrogenase activity was recorded in the abandoned soils and soils under organic systems compared to the conventional farming.

Seleksi Konsorsium Mikroorganisme untuk Pembenah Lumpur Sidoarjo sebagai Media Tanam

ABSTRACT The mud that erupted in Sidoarjo, East Java, has been known from several studies can be used as plant growth media. However, its ability has limitations, particularly due to the very high heavy metal content and phenol will gradually poison the plants. Therefore, a study has been conducted in order to obtain a consortium of microorganisms which have ability to support plants growth and remediate the mud so that further can be used as a growth media. The selected microorganisms consist of Azotobacter sp. KDB2, Bacillus sp. KLBN1, Bacillus sp. BMC4, Pseudomonas sp. BMC6, Trichoderma sp. PJF6 and Trichoderma sp. PJF7F7, which were combined in five consortia, namely K1, K2, K3, K4, and K5. The selection was performed on the ability to produce indole acetic acid, dissolve phosphate, decrease phenol concentration, and decrease the concentration of Pb and Cd ion metals. The results showed that the five consortia have capacity in the five parameters examined. The ability to remove Pb by microbial consortia which consist of Azotobacter, Bacillus, Pseudomonas, and Trichoderma is a new information of the role of microorganism on heavy metal removal. The existence of positive and negative interactions within each consortium lead to differences in the kind of superior consortium generated from each parameter. The consortium K4 showed advantages in 3 parameters, that were in the indole acetic acid production and the Pb and Cd decreases, while the other consortia showed the best capacity only on one of the parameter examined. Therefore, the selected consortium recommended for fixing the Sidoarjo mud is K4, which consists of Azotobacter sp., Bacillus sp. BMC4, Pseudomonas sp. BMC6, Trichoderma sp. PJF6 dan Trichoderma sp. PJF7. Keywords: biofertilizer, bioremediation, Azotobacter, Bacillus, Pseudomonas, Trichoderma

Buffering capacity affects phosphorous solubilization assays in rhizobacteria

Phosphate solubilizing activity of phosphate solubilizing bacteria (PSB) is affected by buffering capacity of soils. It is well known that the buffering capacity of soils can diminish the efficiency of microbial acid production in phosphorus (P) solubilization process. Hence, in the first step of this study by using solid and liquid Sperber media containing organic or inorganic phosphate, more than 100 isolates were isolated, and finally two capable isolates (C1-1O and C16-2O) with highest potential of phosphate solubilizing activity were candidate for identification, and identified as Pseudomonas sp. C16-2O and Pseudomonas sp. C1-1O. In the next stage, their efficiency along with six more chosen PSB (including Pseudomonas putida P13, P. fluorescens Tabriz, Pantoea agglomerans P5, P. agglomerans P5-n, Azotobacter sp. SP5 and Azotobacter sp. SP16) in solubilizing phosphorus ‎from two P sources (rock phosphate: RP and tricalcium phosphate: TCP) in the buffered (100mM Tris–HCl) and un-buffered Pikovskaya's media were evaluated. According to in-vitro experiments, P. fluorescens Tabriz, P. agglomerans P5-n, Azotobacter sp. SP16 and Pseudomonas sp. C16-2O showed the highest solubilization overall, ranged from 258 to 252.7mgL−1. Our results revealed that thoroughly P solubility in buffered condition decreased by 56.2%. Also in the buffered condition, P. putida P13 and Azotobacter sp. SP5 lost their P-solubilization ability while Pseudomonas sp. C16-2O and P. fluorescens Tabriz were the best solubilizers and they solubilized 185.3 and 182.7mgL−1 of insoluble P. P solubility in presence of TCP was 2.55 times more than RP source.

Modelling of microbial polyhydroxyalkanoate surface binding protein PhaP for rational mutagenesis.

SummaryPhasins are unusual amphiphilic proteins that bind to microbial polyhydroxyalkanoate (PHA) granules in nature and show great potential for various applications in biotechnology and medicine. Despite their remarkable diversity, only the crystal structure of PhaPA h from Aeromonas hydrophila has been solved to date. Based on the structure of PhaPA h, homology models of PhaPA z from Azotobacter sp. FA‐8 and PhaPTD from Halomonas bluephagenesis TD were successfully established, allowing rational mutagenesis to be conducted to enhance the stability and surfactant properties of these proteins. PhaPA z mutants, including PhaPA zQ38L and PhaPA zQ78L, as well as PhaPTD mutants, including PhaPTDQ38M and PhaPTDQ72M, showed better emulsification properties and improved thermostability (6‐10°C higher melting temperatures) compared with their wild‐type homologues under the same conditions. Importantly, the established PhaP homology‐modelling approach, based on the high‐resolution structure of PhaPA h, can be generalized to facilitate the study of other PhaP members.

Statistical optimization of a culture medium for biomass and poly(3-hydroxybutyrate) production by a recombinant Escherichia coli strain using agroindustrial byproducts.

A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacter sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 g deproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r2 = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture broth. Similar amounts of PHB were obtained following batch fermentations in a bioreactor. These results show that PHB can be produced efficiently by culturing the recombinant strain in medium containing cheap carbon and nitrogen sources.