Emerging frontiers in microbial-mediated utilization of crop residues for economically valuable biomaterials

Agricultural crop residues include leftover and unmarketable materials, such as crop stover, weeds, leaf litter, sawdust, forest litter, and livestock manure originating from crop cultivation, and post-harvest activities. Such residues are a storehouse of plant nutrients and several other resources and therefore need to be managed in an environment- friendly manner with minimum loss of plant nutrients and other resources that can be recovered. Microbial starter consortia are a key component in the rapid recycling of farm residue wastes and the production of other valuable products, such as biogas, bioethanol/biofuel, enzymes, molecules, and metabolites. Recent advances in microbial biotechnology can also facilitate the conversion of farm residues into economically valuable materials, i.e. soil additives, adsorbents, energy, and enzymes, thereby contributing to a circular economy. This special issue attempts to compile the latest advancements in the field of agricultural crop residue management for enhanced nutrient recycling and resource recovery by the use of compost starters and inoculant formulations.

Experimental investigation and mechanism analysis: Effect of concentration and temperature on the heat transfer characteristics of novel MWCNT-mustard oil nanofluid

ABSTRACT. The bio-oils as alternative lubricating fluid are potential solution for the automotive and industrial mechanical systems. The development of novel renewable and non-toxic bio-oils with better heat transfer distinctiveness will strengthen the economy of farmers in the agricultural based countries. The most innovative approach to improve the heat transfer characteristics of bio-oils is converting it into nanofluids by dispersing nanomaterials which has extremely high heat transfer characteristics. In this study, MWCNT-Mustard oil nanofluids were formulated through ultrasonication and their dispersion stability was estimated through Zeta-potential technique.  The thermal stability of the MWCNT-Mustard oil nanofluids are estimated through thermogravimetric analysis and concentration and temperature dependent density, thermal conductivity and specific heat capacity of MWCNT-Mustard oil nanofluids are also determined and their characteristics are discussed. The heat transfer characteristics of MWCNT-Mustard oil nanofluids observed through the heat pipe test rig at different inlet temperatures, mass flow rate of nanofluids and Reynolds number. The results exhibits that the dispersion of MWCNT enhances the heat transfer characteristics of MWCNT-Mustard oil nanofluids.   KEY WORDS: Non-toxic bio-oils, Nanomaterials, Nanofluids, Thermogravimetric analysis, MWCNT, Mustard oil Bull. Chem. Soc. Ethiop. 2022, 36(3), 675-686.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i3.16

Co-cultivation of Streptomyces and microalgal cells as an efficient system for biodiesel production and bioflocculation formation

The phytohormone producing Streptomyces rosealbus MTTC 12,951 (S.R) and green microalga Chlorella vulgaris MSU-AGM 14 (C.V) were cultivated in co-culture system to evaluate exogenous hormonal activity. Biosynthesis of indole-3-acetic acid (IAA) and their precursors were quantitatively evaluated by employing High Performance Liquid Chromatography (HPLC). The concentration of IAA (0.72 ± 0.02 µg mL^-1) was observed to be elevated in co-cultivation system due to symbiotic interaction between Streptomyces and microalgae. In exchange, microalgae produced adequate volume of tryptophan (Trp) to induce IAA biosynthesis. The Trp stress in late exponential phase encouraged lipid accumulation (175 ± 10 mg g^-1). The bioflocculation property of microalgae ensures potential and economic viable harvesting process by reducing 148% input energy compared to conventional method. The overall results evidenced that C.V co-cultivation with S.R exhibits promotional behavior and serves as a promising cultivation process for microalgae in terms of cost efficiency and energy conservation.

Efficacy of marine cyanobacterium Oxynema thaianum ALU PBC5 against multi drug resistant Gram negative pathogens

AIM

Emergence of extended antibiotic resistance among several human bacterial pathogens often leads to the failure of existing antibiotics to treat bacterial infections worldwide. Hence, the present study is aimed to explore antibacterial activity of marine cyanobacterium against MDR pathogens.

METHODS AND RESULTS

The cyanobacterial samples were collected and isolated from Thondi Palk Strait region. The isolate was subjected to polarity based solvent extraction and checked for their antibacterial activity against test bacterial pathogens. The active principles from chloroform extract of Oxynema thaianum (CEOT) were partially purified through thin layer chromatography (TLC). The active principle with highest activity was further characterized by FTIR, high performance liquid chromatography (HPLC) and gas chromatography mass spectrometry (GC-MS) analysis. Among the eight extracts tested, CEOT showed effective zone of clearance against ESBL producing Escherichia coli and Klebsiella pneumoniae in disc diffusion method. In TLC, all the purified five fractions were eluted and tested for their antibacterial activity against test pathogens. The third fraction showing maximum activity was subjected to HPLC analysis for checking its purity. In GC-MS analysis, 9-octadecenoic acid, methyl ester and hexadecanoic acid were identified as the major chemical compounds.

CONCLUSION

Hence, the present study was concluded that O. thaianum ALU PBC5 is a promising agent to treat ESBL producing MDR bacterial pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the pioneer study on screening and isolation of bioactive compounds from the marine cyanobacteria against MDR pathogens such as E. coli and K. pneumoniae. Here, 9-octadecenoic acid, methyl ester and hexadecanoic acid were identified as the major chemical compounds through TLC, FTIR, HPLC and GC-MS. From this screen, we identified the bioactive compounds against ESBL producing multidrug resistant pathogens such as E. coli and K. pneumoniae.

Arbuscular mycorrhizal fungi spore propagation using single spore as starter inoculum and a plant host

AIMS

The propagation of pure cultures of arbuscular mycorrhizal fungal (AMF) is an essential requirement for their large-scale agricultural application and commercialization as biofertilizers. The present study aimed to propagate AMF using the single-spore inoculation technique and compare their propagation ability with the known reference spores.

METHODS AND RESULTS

Arbuscular mycorrhizal fungal spores were collected from salt-affected Saemangeum reclaimed soil in South Korea. The technique involved inoculation of sorghum-sudangrass (Sorghum bicolor L.) seedlings with single, healthy spores on filter paper followed by the transfer of successfully colonized seedlings to 1-kg capacity pots containing sterilized soil. After the first plant cycle, the contents were transferred to 2·5-kg capacity pots containing sterilized soil. Among the 150 inoculated seedlings, only 27 seedlings were colonized by AMF spores. After 240 days, among the 27 seedlings, five inoculants resulted in the production of over 500 spores. The 18S rDNA sequencing of spores revealed that the spores produced through single-spore inoculation method belonged to Gigaspora margarita, Claroideoglomus lamellosum and Funneliformis mosseae. Furthermore, indigenous spore F. mosseae M-1 reported a higher spore count than the reference spores.

CONCLUSIONS

The AMF spores produced using the single-spore inoculation technique may serve as potential bio-inoculants with an advantage of being more readily adopted by farmers due to the lack of requirement of a skilled technique in spore propagation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results of the current study describe the feasible and cost-effective method to mass produce AMF spores for large-scale application. The AMF spores obtained from this method can effectively colonize plant roots and may be easily introduced to the new environment.

Immediate effect of bitter gourd, ash gourd, Knol-khol juices on blood sugar levels of patients with type 2 diabetes mellitus: A pilot study

AIM

The aim of this study was to investigate the immediate effect of bitter gourd, Knol-khol, and ash gourd juices on blood glucose level among Type II diabetes mellitus patients.

METHODS

In 2015, pilot study was conducted randomly enrolling 30 patients with type 2 diabetes mellitus into three groups in SRK college, India. The first group received bitter gourd juice at FBS range between 120 to 300 mg per dl. The second, third group received Knol-khol, ash gourd juice respectively in the same range of fasting blood sugar level. Blood sugar level was evaluated ½ hour interval till 2 h after received respective juices. Data were collected for statistical analysis.

RESULTS

The mean blood glucose concentration in bitter gourd group was not statistically significant between time points, (P = .176). However, 90 min after the intake of bitter gourd juice shows statistical significant reduction of blood glucose level when compare with fasting level, (p = .049). After Knol khol juice the mean blood glucose level differed statistically significant between time points, shown in (p = .029). But no statistical changes seen in ash gourd group. As a result bitter gourd juice is immediately reducing the blood glucose level, while Knol khol juice reduces the blood sugar level gradually for longer period of 120 min.

CONCLUSION

This study shows the significance of hypoglycemic effects of bitter gourd and Knol khol juices among the type 2 Diabetic patients. Hence Bitter gourd juice, Knol khol juices may be beneficial in Diabetes patients to reduce the blood glucose level.

Green synthesized silver nanoparticles from Garcinia imberti bourd and their impact on root canal pathogens and HepG2 cell lines

Nanoparticle biosynthesis using the extract of medicinal plants in a non-hazardous mode has gained wide attention for various applications in nanomedicine.

Screening of Cellulase and Pectinase by Using <i>Pseudomonas fluorescence</i> and <i>Bacillus subtilis</i>

A study was conducted to determine the Production of cellulase and pectinase enzyme by using Plant growth promoting rhizobacteria like Pseudomonas fluorescence and Bacillus subtilis. These to micro organism are isolated by serial dilution method. One gram of soil sample was diluted in to 10 ml of sterile distilled water and 1 ml of sample solution was serially diluted in 9ml of sterile water up to 10 dilution. Each sample from dilution 10-5 and 10-6 were taken and streaked in to KB and NA medium and incubate at 24 hrs. After 24 hrs Pseudomonas fluorescence and Bacillus subtilis was observed in the medium of KB and NA medium. Both the culture was sub cultured and maintain in the same for the further work. CMCase medium was prepared and sterilized by autoclave for 121 °C for 15 minutes after sterilization these medium contain petriplate was streaked by bacteria and incubates for 48h after incubation period a clear halo zone was produced by these bacteria among these bacteria Pseudomonas fluorescence are able to produce high amount of cellulose compare to Bacillussubtilis. Pectin agar medium was prepared and sterilized by autoclave for 121 °C for 15 minutes after sterilization these medium contain petriplate was streaked by bacteria incubates for 48h after incubation period a clear halo zone was produced by these bacteria, among these bacteria Pseudomonas fluorescence are able to produce high amount of Pectinase compare to Bacillus subtilis. Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth by a wide variety of mechanisms.

Screening of Cellulase and Pectinase by Using <i>Pseudomonas fluorescence</i> and <i>Bacillus subtilis</i>

A study was conducted to determine the Production of cellulase and pectinase enzyme by using Plant growth promoting rhizobacteria like Pseudomonas fluorescence and Bacillus subtilis. These to micro organism are isolated by serial dilution method. One gram of soil sample was diluted in to 10 ml of sterile distilled water and 1 ml of sample solution was serially diluted in 9ml of sterile water up to 10 dilution. Each sample from dilution 10-5 and 10-6 were taken and streaked in to KB and NA medium and incubate at 24 hrs. After 24 hrs Pseudomonas fluorescence and Bacillus subtilis was observed in the medium of KB and NA medium. Both the culture was sub cultured and maintain in the same for the further work. CMCase medium was prepared and sterilized by autoclave for 121 °C for 15 minutes after sterilization these medium contain petriplate was streaked by bacteria and incubates for 48h after incubation period a clear halo zone was produced by these bacteria among these bacteria Pseudomonas fluorescence are able to produce high amount of cellulose compare to Bacillussubtilis. Pectin agar medium was prepared and sterilized by autoclave for 121 °C for 15 minutes after sterilization these medium contain petriplate was streaked by bacteria incubates for 48h after incubation period a clear halo zone was produced by these bacteria, among these bacteria Pseudomonas fluorescence are able to produce high amount of Pectinase compare to Bacillus subtilis. Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth by a wide variety of mechanisms.

A simple and rapid single kernel screening method to estimate amylose content in rice grains

INTRODUCTION

In rice breeding programmes large number of grain samples are routinely analysed for amylose content (AC) through a tedious spectrophotometric method that also involves high reagent costs.

OBJECTIVE

Here, we propose a rapid and economic screening technique for assessment of AC based on the amylose-iodine complex formation in the cut grains of rice, which we refer to as the cut grain dip (CGD) method.

METHODS

The CGD method involves cutting the rice kernels in the middle with a pair of scissors and dipping the cut end in an optimised iodide:iodine (KI-I) solution termed the rapid amylose detection solution (RADS).

RESULTS

It was found that the time taken for deep blue colouration by the cut end of the grains after dipping in RADS was proportional to the AC. The CGD method was further validated in a large set of rice mutants with varied AC.

CONCLUSION

The proposed method can be used to screen samples for AC rapidly, with a single rice caryopsis, without any costly equipment and can be especially suitable for screening of mutants and segregants with altered AC in large breeding populations.

Isolation, molecular characterization and growth-promotion activities of a cold tolerant bacterium Pseudomonas sp. NARs9 (MTCC9002) from the Indian Himalayas

A bacterium that grows and expresses plant growth promotion traits at 4 degrees C was isolated from the rhizospheric soil of Amaranth, cultivated at a high altitude location in the North Western Indian Himalayas. The isolate was Gram negative and the cells appeared as rods (2.91 x 0.71 microm in size). It grew at temperatures ranging from 4 to 30 degrees C, with a growth optimum at 28 degrees C. It exhibited tolerance to a wide pH range (5-10; optimum 8.0) and salt concentrations up to 6% (wt/vol). Although it was sensitive to Rifampicin (R 20 microg mi-1), Gentamicin (G 3 microg mi-1), and Streptomycin (S 5 microg mi-1), it showed resistance to higher concentrations of Ampicillin (A 500 microg mi-1), Penicillin (P 300 microg mi-1), Polymixin B sulphate (Pb 100 microg mi-1) and Chloramphenicol (C 200 microg mi-1). The 16S rRNA sequence analysis revealed maximum identity with Pseudomonas lurida. The bacterium produced indole Acetic Acid (IAA) and solubilizes phosphate at 4, 15 and 28 degrees C. It also retained its ability to produce rhamnolipids and siderophores at 15 degrees C. Seed bacterization with the isolate enhanced the germination, shoot and root lengths of thirty-day-old wheat seedlings by 19.2, 30.0 & 22.9% respectively, as compared to the un-inoculated controls.

Growth promotion of wheat seedlings by Exiguobacterium acetylicum 1P (MTCC 8707) a cold tolerant bacterial strain from the Uttarakhand Himalayas

Exiguobacterium acetylicum strain 1P (MTCC 8707) is a gram-positive, rod-shaped, yellow pigmented bacterium isolated from soil on nutrient agar plates at 4°C. The identity of the bacterium was arrived on the basis of the biochemical characterization, BIOLOG sugar utilization pattern and sequencing of the 16S rRNA gene. It grew at temperatures ranging from 4 to 42°C, with temperature optima at 30°C. It expressed multiple plant growth promotion attributes such as phosphate solubilization, indole acetic acid (IAA), siderophore and hydrogen cyanide (HCN) production, differentially at suboptimal growth temperatures (15 and 4°C). At 15°C it solubilized phosphate (21.1 μg of P ml(-1) day(-1)), and produced IAA (14.9 μg ml(-1) day(-1)) in tryptophan amended media. Qualitative detection of siderophore production and HCN were possible at 15°C. At 4°C it retained all the plant growth promotion attributes. Seed bacterization with the isolate, positively influenced the growth and nutrient uptake parameters of wheat seedlings in glass house studies at suboptimal cold growing temperatures.

Isolation and characterization of nonrhizobial plant growth promoting bacteria from nodules of Kudzu (Pueraria thunbergiana) and their effect on wheat seedling growth

The leguminous vine Kudzu (Pueraria thunbergiana) is an introduction into the N. W. Himalayan region of India. Despite its value as a fodder and cover crop, little is known about the nature of the nodule microflora. In an attempt to study the nodule bacteria, we isolated and characterized three nonrhizobial plant growth promoting bacteria from surface sterilized nodules of Kudzu. Based on the sequencing of the 16 S r RNA gene, the isolates were designated as Bacillus thuringiensis KR-1, Enterobacter asburiae KR-3, and Serratia marcescens KR-4. Crystalline bodies were detected in the isolate KR-1, confirming its identity as B. thuringiensis. Under in vitro conditions, all three isolates were found to produce indole acetic acid. Other plant growth promotion attributes such as P solubilization, hydrogen cyanide production, and ammonia production varied among the isolates. All of the three isolates promoted growth and positively influenced nutrient uptake parameters of wheat seedlings.

Inhibitory activity of pine needle tannin extracts on some agriculturally resourceful microbes

Crude extracts of water and solvent extractable tannin fractions from pine needles were found to contain tannin concentrations of 10.15% and 13.15% tannic acid equivalents respectively. Thin Layer Chromatography revealed the presence of four distinct phenolic compounds, amongst which two were tannic acid like compounds. Both the extracts were found to be inhibitory to several microbes of agricultural importance. Amongst the bacterial strains studied, Azotobacter sp (VL-A2) was able to tolerate upto 1000 ppm of crude tannin concentration without any growth inhibition. While growth of Rhizobium (VL-R1) and Bacillus halodurans (MTCC 7181) was inhibited by crude tannin concentrations of 50 and 100 ppm respectively of both water and solvent extracted tannins. Among the fungal genera, Pleurotus djamor was found to tolerate up to 10000 ppm of crude tannins, while Trichoderma virescens (MTCC 6321) and T. reesii could tolerate up to 3000 ppm of both water extractable and acetone extractable crude tannins without any growth inhibition.

Design and development of a simple laboratory model to detect (15)N enrichment in cyanobacterial biomass and extra cellular ammonia using (15)N gas

A laboratory scale working model that could detect the (15)N enrichment in cyanobacterial biomass and extracellular ammonia, using (15)N gas under in vitro conditions was designed and fabricated. Using the model, (15)N enrichment of 0.48% atom excess was detected in the cyanobacterial biomass on the 30 d after inoculation. The (15)N enrichment increased linearly in the extracellular ammoniacal fraction from the 20 d onward. The model would prove to be a useful tool to quantify the extent of (15)N enrichment under in vitro conditions using (15)N gas.

Pigment analysis and ammonia excretion in herbicide tolerant cyanobacteria

Isolation of cyanobacteria was attempted from herbicide applied rice soils. The predominant genera were Westiellopsis followed by Anabaena, Nostoc and Oscillatoria. The herbicide tolerance was further tested by growing the cyanobacterial cultures in BG-11 medium supplemented with varying concentrations of the commonly used rice herbicide, viz butachlor under in vitro condition. The chlorophyll-a, phycobiliproteins and ammonia excretion were assessed at periodic intervals. Westiellopsis showed the maximum tolerance followed by Anabaena, Nostoc and Oscillatoria.