Halo Zone Research Articles

Enhancing phosphorus availability and growth of green gram (Vigna radiata) in acidic red and laterite soil through liquid formulations of native phosphate solubilizing bacteria

Phosphorus (P) availability in acid soils is often limited due to its fixation with various soil components. This leads to low use efficiency of P fertilizers and raises environmental concerns when they are used in excess. Phosphate-solubilizing bacteria (PSB) have the potential to enhance P availability by solubilizing insoluble P forms. In this study, twenty-five PSB strains were initially isolated from acidic red and laterite soils in eastern India. Among them, ten bacteria formed a clear halo zone in Pikovskaya agar plates. The P releasing ability of these bacteria from different insoluble P sources was evaluated. The PSB strain AJ14, identified as Enterobacter sp., exhibited high P releasing capacity from tri-calcium phosphate, rock phosphate, ferric phosphate, and aluminum phosphate. Additionally, the strain demonstrated the ability to release zinc and potassium from insoluble sources. To improve the shelf life and efficacy of the PSB strain, liquid biofertilizer formulations were developed using polymeric additives such as polyvinylpyrrolidone, polyethylene glycol, glycerol, carboxymethyl cellulose, and tween 20. The liquid formulations showed enhanced survival and viability of the PSB strain compared to solid carrier-based biofertilizers. In a pot culture experiment with green gram plants, the liquid formulations significantly increased soil available P, dry matter yield, and P uptake by plants compared to the control and solid carrier-based biofertilizer treatment. Mitscherlich equation parameters indicated the greater effectiveness of the liquid formulations. The results suggest that liquid formulations of the PSB strain AJ14 can improve P utilization efficiency and plant growth in acidic red and laterite soils.

Comparing the population density, colony diversity, and phosphate solubilization ability between rice root endophytic and rice rhizospheric soil bacteria from organic wetland

Abstract Phosphate-solubilizing bacteria (PSB) play important roles in the agricultural systems. The present study aims to compare the population density, colony diversity, and phosphate solubilization ability between rice root endophytic bacteria (RRoEB) and rice rhizospheric soil bacteria (RRzSB) from organic wetland. By spread plate method, bacteria were isolated directly using Pikovskaya’s agar and indirectly through other media, namely Nutrient Agar (NA), Starch Casein Agar (SCA), Jensen, and Yeast Extract Mannitol Agar (YEMA). Each distinct colony based on the morphology on the respective media was screened for phosphate solubilization ability by subculturing on Pikovskaya’s agar. The phosphate solubilizing index (PSI) was measured from the halo zone formation. The results showed that by direct isolation, 6 RRoEB and 5 RRzSB were able to phosphate solubilization. By indirect isolation from NA, SCA, Jensen, and YEMA, 2, 3, 1, and 3 isolates of RRoEB and 4, 3, 1, and 3 isolates of RRzSB showed the capability as phosphate solubilizer. Although the highest colony diversity of PSB was obtained from direct isolation, however the highest PSI was yielded from indirect isolation, namely isolates J1R1 (3.53) and Y1S1 (2.48). The highest PSI from direct isolation was obtained by P1R5 (1.90) and P1S1 (1.51).

Isolation, screening and characterization of efficient cellulose-degrading fungal and bacterial strains and preparation of their consortium under in vitro studies.

In this investigation, cellulose-degrading fungi and bacteria were isolated from different partially decomposed cellulose-rich substrates, such as groundnut residues, rice straw, and rotten wood, following dilution plating techniques on carboxymethyl cellulose agar media and screening for potential cellulose degradation ability. The development of a clear halo zone surrounding the microbial colonies during the initial screening process using the Congo red test (20 isolates) suggested cellulose hydrolysis, and the highest cellulase production activity was implied by the isolates with the largest clear zone ratio (9 isolates). Using both macroscopic and microscopic examinations, as well as standard biochemical tests outlined in Bergey's Manual of Determinative Bacteriology, the genus-level identification of fungi and bacteria was accomplished. In order to molecularly identify the 4 isolatedfungal and bacterial strains at the species level after being ultimately selected for cellulase production potential under in vitro studies, fungal and bacterial DNA was extracted and amplified by PCR using the universal primers ITS1 and ITS4 for fungi (ITS rRNA, 5.8S rRNA) and 8F and 1492R for bacterial isolates (16S rRNA). After sequencing, the PCR results were compared to other comparable sequences in GenBank (NCBI). Based on the available NCBI data, phylogenetic analysis of their ribosomal gene partial sequences revealed that DAJ2 (PP086700) shares 100% homology with Aspergillus foetidus, DTJ4 (PP086699) shares 99.74% similarity with Trichoderma atrobrunnium, DBJ6 (PP082584) shares 100% identity with Priestia megaterium, and DMB9 (PP082585) shares 99.88% homology with Micrococcus yunnanensis. The cellulolytic potential of Phanerochaete chrysosporium is well established. Therefore, it was considered a standard culture for comparison and was collected from the MTCC, Chandigarh, India. Overall, all 4 selected isolates and the check organism were mutually compatible or synergistic with each other, and their consortium is useful for the accelerated decomposition of organic constituents during rapid composting.

Mycodegradation of low-density polyethylene by Cladosporium sphaerospermum, isolated from platisphere

Plastic accumulation is a severe threat to the environment due to its resistivity to thermal, mechanical and biological processes. In recent years, microbial degradation of plastic waste disposal is of interest because of its eco-friendly nature. In this study, a total of 33 fungi were isolated from the plastisphere and out of which 28 fungal species showed halo zone of clearance in agarized LDPE media. The fungus showing highest zone of clearance was further used to evaluate its degradation potential. Based on morphological and molecular technique, the fungus was identified as Cladosporium sphaerospermum. The biodegradation of LDPE by C. sphaerospermum was evaluated by various methods. The exposure of LDPE with C. sphaerospermum resulted in weight loss (15.23%) in seven days, higher reduction rate (0.0224/day) and lower half-life (30.93 days). FTIR analysis showed changes in functional group and increased carbonyl index in LDPE treated with C. sphaerospermum. SEMimages evidenced the formation of pits, surface aberrations and grooves on the LDPE film treated with the fungus whereas the untreated control LDPE film showed no change. AFM analysis confirmed the surface changes and roughness in fungus treated LDPE film. This might be due to the extracellular lignolytic enzymes secreted by C. sphaerospermum grown on LDPE. The degradation of polyethylene by Short chain alkanes such as dodecane, hexasiloxane and silane were identified in the extract of fungus incubated with LDPE film through GC–MS analysis which might be due to the degradation of LDPE film by C. sphaerospermum. This was the first report on the LDPE degradation by C. sphaerospermum in very short duration which enables green scavenging of plastic wastes.

The comparative plastisphere microbial community profile at Kung Wiman beach unveils potential plastic-specific degrading microorganisms.

Plastic waste is a global environmental issue that impacts the well-being of humans, animals, plants, and microorganisms. Microplastic contamination has been previously reported at Kung Wiman Beach, located in Chanthaburi province along with the Eastern Gulf of Thailand. Our research aimed to study the microbial population of the sand and plastisphere and isolate microorganisms with potential plastic degradation activity. Plastic and sand samples were collected from Kung Wiman Beach for microbial isolation on agar plates. The plastic samples were identified by Fourier-transform infrared spectroscopy. Plastic degradation properties were evaluated by observing the halo zone on mineral salts medium (MSM) supplemented with emulsified plastics, including polystyrene (PS), polylactic acid (PLA), polyvinyl chloride (PVC), and bis (2-hydroxyethyl) terephthalate (BHET). Bacteria and fungi were identified by analyzing nucleotide sequence analysis of the 16S rRNA and internal transcribed spacer (ITS) regions, respectively. 16S and ITS microbiomes analysis was conducted on the total DNA extracted from each sample to assess the microbial communities. Of 16 plastic samples, five were identified as polypropylene (PP), four as polystyrene (PS), four as polyethylene terephthalate (PET), two as high-density polyethylene (HDPE), and one sample remained unidentified. Only 27 bacterial and 38 fungal isolates were found to have the ability to degrade PLA or BHET on MSM agar. However, none showed degradation capabilities for PS or PVC on MSM agar. Notably, Planococcus sp. PP5 showed the highest hydrolysis capacity of 1.64 ± 0.12. The 16S rRNA analysis revealed 13 bacterial genera, with seven showing plastic degradation abilities: Salipiger, Planococcus, Psychrobacter, Shewanella, Jonesia, Bacillus, and Kocuria. This study reports, for the first time of the BHET-degrading properties of the genera Planococcus and Jonesia. Additionally, The ITS analysis identified nine fungal genera, five of which demonstrated plastic degradation abilities: Aspergillus, Penicillium, Peacilomyces, Absidia, and Cochliobolus. Microbial community composition analysis and linear discriminant analysis effect size revealed certain dominant microbial groups in the plastic and sand samples that were absent under culture-dependent conditions. Furthermore, 16S and ITS amplicon microbiome analysis revealed microbial groups were significantly different in the plastic and sand samples collected. We reported on the microbial communities found on the plastisphere at Kung Wiman Beach and isolated and identified microbes with the capacity to degrade PLA and BHET.

Membrane filtration for enumeration of Listeria monocytogenes at low levels on salad leaf

The reference method BS EN ISO 11290-2:2017 is insufficiently sensitive to enumerate Listeria monocytogenes in most commercially prepared leaf salads. A more sensitive method for enumerating low levels of Listeria spp. is required to evaluate the impact of process changes and the effect of Listeria control mechanisms in chilled foods including salad leaf. Membrane filtration allows larger volumes of food to be tested but care must be taken to avoid excessive pigmentation of the membranes by damage to leaf during sample preparation and bag homogenisation. Blue-green colonies can be identified after 48 h of incubation of the membranes on Listeria Ottaviani and Agosti selective agar plates, these colonies are indicative of Listeria spp., but halo zones cannot be distinguished. Results obtained by this technique are reported showing enumeration of 5 CFU/g added L. monocytogenes.

Dibutyl phthalate degradation by Paenarthrobacter ureafaciens PB10 through downstream product myristic acid and its bioremediation potential in contaminated soil

Dibutyl phthalate (DBP) is a widely used plasticizer to make plastic flexible and long-lasting. It is easily accessible in a broad spectrum of environments as a result of the rising level of plastic pollution. This compound is considered a top-priority toxicant and persistent organic pollutant by international environmental agencies for its endocrine disruptive and carcinogenic propensities. To mitigate the DBP in the soil, one DBP-degrading bacterial strain was isolated from a plastic-polluted landfill and identified as Paenarthrobacter ureafaciens PB10 by 16S rRNA gene sequence-based homology. The strain was found to develop a distinct transparent halo zone around grown colonies on an agar plate supplemented with DBP. The addition of yeast extract (100 mg/L) as a nutrient source accelerated cell biomass production and DBP degradation rate; however, the presence of glucose suppressed DBP degradation by the PB10 strain without affecting its ability to proliferate. The strain PB10 was efficient in eliminating DBP under various pH conditions (5.0–8.0). Maximum cell growth and degradation of 99.49% at 300 mg/L DBP were achieved in 72 h at the optimized mineral salt medium (MS) conditions of pH 7.0 and 32 °C. Despite that, when the concentration of DBP rose to 3000 mg/L, the DBP depletion rate was measured at 79.34% in 72 h. Some novel intermediate metabolites, like myristic acid, hexadecanoic acid, stearic acid, and the methyl derivative of 4-hydroxyphenyl acetate, along with monobutyl phthalate and phthalic acid, were detected in the downstream degradation process of DBP through GC-MS profiling. Furthermore, in synchronization with native soil microbes, this PB10 strain successfully removed a notable amount of DBP (up to 54.11%) from contaminated soil under microcosm study after 10 d. Thus, PB10 has effective DBP removal ability and is considered a potential candidate for bioremediation in DBP-contaminated sites.

Isolation of a potential rock phosphate solubilizing Aspergillus sp. towards development of biofertilizer

Phosphorus (P) is one of the key bio elements that limits agricultural production. Although Sri Lanka is endowed with rock phosphate deposits, practical means to utilize this resource are limited. Phosphate-solubilizing fungi (PSF) play an important role in enhancing the bioavailability of soil phosphorus to plants. In this study, fungi from eight soil samples in Kaikawala, Sri Lanka, were isolated using spread plate method and analyzed for its phosphate solubility capacity. One fungal isolate with significant halo zones on Pikovskaya’s agar (PVK) plates, containing 0.5% tricalcium phosphate, was identified. After purification, the isolate was transferred to three media setups: PVK with 0.5% apatite (ERP) as the phosphate source, PVK with 0.5% tricalcium phosphate as a positive control, and PVK without P source as a negative control and analyzed for the solubilization index (SI). DNA sequences of the internal transcribed spacers with 5.8S region of ribosomal DNA (ITS1-5.8S-ITS2) was analyzed with universal primer pair ITS4-F/ITS5-R to determine the identity of the species. Fungal isolate PSF01 showed a phosphate solubilizing activity on both PVK media, ERP (1.07 ± 0.03 cm SI) and tricalcium phosphate (1.07 ± 0.01 cm), with similar effects (p > 0.05). However, the SI in the negative control was 1.00 ± 0.00 cm without halo zone (p < 0.05). The fungal strain is fast growing with initially white but quickly changing to black colonies after producing conidial spores on potato dextrose agar with distinctive conidial heads and pale-yellow lower surface characterized as Aspergillus. Sanger DNA sequencing identified the fungus as Aspergillus niger (99%) and a phylogenetic tree was constructed using MEGA11 software using reference data obtained from NCBI GenBank data to identify the isolated PSF01. Consequently, our preliminary studies demonstrate the importance of examining more soil samples to identify PSF for sustainable agricultural applications in the future.

Exploration and Characterization of High-Efficiency Phosphate-Solubilizing Bacteria Isolates from Chickpea Rhizospheric Soil

The study was conducted during April, 2021 to June, 2022 to study the isolation and identification of high effective strains of phosphate solubilizing bacteria and evaluation the ability to solubilize tricalcium phosphate in vitro. Microorganisms that live in soil are actively involved in the carbon, nitrogen, sulphur, and phosphorus cycles in nature, enabling them to maintain ecological balance. Phosphate-solubilizing microbes are used as agricultural biofertilizers and play an essential role in plant nutrition by enhancing phosphate uptake. Phosphate is one of the most important macronutrients necessary for the growth and development of plants. Numerous microorganisms present in the rhizosphere solubilize insoluble phosphorus, making it readily available to plants. Fourteen phosphate-solubilizing bacterial colonies were identified on Pikovskaya’s agar medium, containing insoluble tricalcium phosphate (TCP) from rhizospheric soil. Among them, eight colonies showing clear halo zones around the microbial growth were considered as phosphate-solubilizing. All isolates showing the highest phosphate solubilization index (PSI), ranging from 2.8 to 4.03, were selected for further qualitative and quantitative studies. Out of these eight potent isolates, two strains showed the maximum PSI: V7 (4.03) and V8 (3.85) in agar plates, along with a high production of soluble phosphate, measuring 448.03 and 441.43 mg l-1, and a greater reduction in pH in the broth culture. The morphological, biochemical, and molecular identification of V7 and V8 strains revealed them to belong the Acinetobacter and Paenibacillus genera, respectively, and were phylogenetically close to Acinetobacter baumannii and Paenibacillus lautus species.

Isolation and Molecular Characterization of Phosphate-Solubilizing Bacteria from Root Nodules of Cowpea (Vigna unguiculata) Seeds Planted at Ota, Ogun State, Nigeria

In line with the race to increase worldwide food production to cater to the growing world population, there is a growing interest in exploring the plant growth-promoting attributes of rhizobia. This is in a bid to curb environmental and health damage arising from the use of chemical fertilizers. Hence, the objective of this work was to isolate and characterize phosphate-solubilizing bacteria from root nodules of cowpea (Vigna unguiculata) seeds planted at Ota, Ogun State, Nigeria using standard techniques. The 16S rRNA gene amplification and sequencing of the organisms identified the 2 isolates which were positive for phosphate solubilization as Pseudomonas straminea and Ralstonia mannitolilytica. Their sequences were deposited to GenBank with the assession numbers MK590690 and MK590695 respectively. Isolate Pseudomonas straminea was more efficient and produced a halo zone (16mm) with a phosphate solubility index (PSI) of 2.0 while isolate Ralstonia mannitolilytica produced a halo zone (14 mm) with PSI of 1.6 after 7 days of incubation. The results obtained from this study indicate that these organisms could be potential candidates to be used as biofertilizers to improve crop yield.

Isolation and Characterization of Cellulolytic Fungi From Decomposing Rice Straws

Rice straw is an agricultural waste that is normally produced after the paddy is harvested. Rice straw, which is high in cellulose content, makes it difficult to degrade. It is burnt away by most farmers as this method saves time and labor. However, the burning of rice straws could have a serious impact on the environment and human health in general. To overcome this, biodegradation using fungi should be applied in degrading the cellulosic waste. In this study, rice straws from Bagan Serai, Perak were collected. Decomposing of rice straws was prepared by adding coffee residue, cow and chicken dung, and phosphate fertilizer. A total of 18 isolates were isolated and purified from the sample and the isolates were brought further to macroscopic by observing the morphology. Morphological and microscopic characterization using a microscope was performed where the structure of the isolate was observed and their respective genus level was deduced. Among the 18 isolates, most of them were Aspergillus. Next, cellulase screening was done using carboxymethylcellulose (CMC) agar with Gram iodine staining. Isolate C7 showed the largest diameter of the halo zone at 48 h of incubation whereas isolate 4D has the most significant increase of halo zone in 24-h duration.

In vitro evaluation of probiotic properties of yeasts and lactic acid bacteria isolated from ersho samples collected from different parts of Ethiopia

ABSTRACT Ersho is an undefined starter culture used for Ethiopian injera production, and it is a good source of yeasts and lactic acid bacteria (LAB). However, few researchers have been done on the characterization of yeasts and LAB from ersho samples as a source of probiotics. The objective of the current work was to isolate and screen yeasts and LAB from ersho samples and in vitro characterization of their probiotic properties. An experimental research design was used. A total of 55 ersho samples were collected. Based on the ersho samples, 220 yeast colonies and 220 LAB colonies were isolated and purified. For the probiotic characterization, three yeasts (4A, 14D, 54A) and three LAB (1A, 13E, and 55A) were chosen. The isolates 4A, 14D, 54A, 1A, 13E, and 55A were identified as Saccharomyces cerevisiae KRSAN1, Saccharomyces cerevisiae JYC2577, Kazachstania humilis, Enterococcus lactis, Lactobacillus paracasei, and Lactobacillus species, respectively. All the isolates showed positive probiotic characteristics. They had very good acid resistance (percentage survival > 80%), high bile salt resistance (percentage survival > 140%), high cell surface hydrophobicity (>40%), high levels of auto-aggregation (>40%), variable co-aggregation with pathogens (ranged between 42% and 72%), variable antimicrobial activity (clear halo zone ranged from 4.0 to 31 mm), and variable antibiotic resistance responses. The results indicated that the ersho samples can be used as yeast and LAB sources for developing food and probiotic starter cultures.

Biocontrol of Fusarium wilt disease by endophytic Bacillus xiamenensis BS10 isolated from the root nodules of Brassica nigra (mustard plant) and analysis of defence molecular biomarkers in the greenhouse and field trial

Endophytic bacteria possess positive effects on their host plants, including, secondary metabolite induction, disease-resistance improvement, and growth promotion. Bacillus spp. are considered to be an eco-friendly and bio-safe alternative to traditional chemical fungicides. In our study, a collection of 12 endophytic bacteria were isolated from Brassica nigra root nodules and analyzed for plant growth-promoting activities. The endophytic strain BS10 significantly solubilise phosphate (19 ± 1 mm halo zone), siderophore (17 ± 1 mm halo zone), HCN (18 ± 1 halo zone), and indole acetic acid (205.1 ± 2.8 μg/mL) significantly (p < 0.05) than other isolates. The antifungal activity of isolated endophytes was analyzed using a dual-culture screening method. The antifungal activity against Fusarium oxysporum revealed that the strain BS10 exhibited maximum activity against F. oxysporum and the inhibition rate ranged from 20 ± 1 to 70.2 ± 3.5 % after 4 days of treatment and increased after 8 days (36.9 ± 3.5–75.8 ± 3.2 %) among other endophytes. The cell-free extract decreased fungal growth and the inhibition rate varied between 12 % and 47 % (p < 0.05). The results revealed that the fungal infection of the mustard plants with wilt disease causing F. oxysporum significantly reduced the growth of the mustard plant, and root, shoot length, and dry weight compared with the control (p < 0.05). The infected plants treated with endophyte showed an improvement in the growth parameters (p < 0.05). The endophytes-treated plants showed fewer symptoms of rot disease in mustard plants. The chlorophyll content (2.27-fold), soluble leaf protein (1.22-fold), proline (26 ± 2.8 nM/g fresh weight) were improved in the plant leaves treated with endophyte. The biosynthesis of ascorbate peroxidase, phenylalanine ammonia-lyase, and catalase was improved in the endophyte-treated seeds compared with control seeds (p > 0.05). The isolated B. xiamenensis is an important resource to biocontrol Fusarium wilt diseases in the mustard plant.

Characterization of the pancreas of common pheasant (Phasianus colchicus): A light and transmission electron microscope study.

The present work was carried out to investigate the structure and ultra structure of the pancreas in the common pheasant (Phasianus colchicus). Totally, five healthy adult pheasant were used. The pancreas was assessed using histochemistry and transmission electron microscopy (TEM). The pancreas was composed of four lobes: dorsal, ventral, third, and splenic lobes. These lobes emptied into ascending duodenum through three excretory ducts as: ventral duct, splenic duct, and a common duct for dorsal and third lobes. The exocrine pancreas was constituted of pyramidal-shaped acinar cells with aggregation of zymogen granules at their apical cytoplasm. The endocrine pancreas was identified as large islet of Langerhans as α islets and small islets as β ones. No mixed islet was observed. At the level of TEM, two types of acinar cells were distinguished: Dark cells with electron dense cytoplasm, and indented nucleus, Light cells with electron lucent cytoplasm, and regular nucleus. The α islets were mainly constituted by A and D cells, whereas the β islets principally contained B cells and a few A cells. No D cells were identified in β islets. B cells were characterized by their polymorphic granules which were surrounded by a narrow halo zone. The granules of D cells were quite different. These cells contained large spherical granules with lower density as compared to the A or B granules surrounded by a limiting membrane. In conclusion, the pancreas of the common pheasant has a species-specific feature which must be considered in phylogenic studies. RESEARCH HIGHLIGHTS: The common pheasant's pancreas was composed of four lobes as dorsal, ventral, third, and splenic lobe. There were three excretory ducts. Ventral duct for ventral lobe, a common duct for both dorsal and third lobes, and a distinct splenic duct for splenic lobe. The exocrine acini were composed of two distinct types of cells: dark cells and light cells. The large alpha islets were composed of alpha cells and a few numbers of delta cells and small beta islets were composed of beta cells and a few numbers of alpha cells.

Visual screening of potassium solubilizing bacteria for increasing the solubilization of potassium minerals

Research on potassium solubilizing bacteria (KSB) has recently gained attention, most of it has been focused on the size of the halo zone; however, information regarding KSB growth duration and their potential to reduce the use of chemical fertilizers for sustainable agriculture and to be used as a biofertilizer are still lacking. The aim of this study was to offer a complete, long-term observation of KSB growth. We monitored the growth of two KSB strains that were isolated from the rhizosphere for 7 days on Modified Aleksandrov Medium (MAM) plates. We specifically designed the observation times. These methods were used to distinguish KSB’s capability to solubilize potassium minerals. The results indicated that KSB-12 isolate was capable of producing organic acid and thus solubilizing potassium faster than KSB-19 isolate at 1-4 days of incubation. Interestingly, the solubilizing zone of the KSB-12 isolate decrease after 5 days of incubation, while KSB-19 isolate continued to grow, maintain cell numbers, produce organic acids, and continuously release potassium. Different types of volatile and non-volatile organic acids have an effect on this phenomenon. In conclusion, we provided a well-designed time series study regarding the potassium solubilization efficiency of KSB, determining the fastest and longest strains of potential KSBs.

Geobacillus Bacteriophages from Compost Heaps: Representatives of Three New Genera within Thermophilic Siphoviruses.

We report a detailed characterization of five thermophilic bacteriophages (phages) that were isolated from compost heaps in Vilnius, Lithuania using Geobacillus thermodenitrificans strains as the hosts for phage propagation. The efficiency of plating experiments revealed that phages formed plaques from 45 to 80 °C. Furthermore, most of the phages formed plaques surrounded by halo zones, indicating the presence of phage-encoded bacterial exopolysaccharide (EPS)-degrading depolymerases. Transmission Electron Microscopy (TEM) analysis revealed that all phages were siphoviruses characterized by an isometric head (from ~63 nm to ~67 nm in diameter) and a non-contractile flexible tail (from ~137 nm to ~150 nm in length). The genome sequencing resulted in genomes ranging from 38,161 to 39,016 bp. Comparative genomic and phylogenetic analysis revealed that all the isolated phages had no close relatives to date, and potentially represent three new genera within siphoviruses. The results of this study not only improve our knowledge about poorly explored thermophilic bacteriophages but also give new insights for further investigation of thermophilic and/or thermostable enzymes of bacterial viruses.

Isolation and Screening of Lignocellulolytic Microbes from Cow Dung for Rapid Composting of Rice Straw

The present work aimed to isolate and screen the lignocellulolytic microbes from cow dung, partially decomposed straw, forest soil. A total of 60 isolates from which 41 bacterial, 15 fungal and 4 actinomycetes distinct isolates were obtained were further subjected to lignocellulolytic screening. The 60 isolates when screened for their ability to produce cellulase enzyme 21 bacterial isolates showed positive. Highest halo zone was shown with greater hydrolysis capacity ranging from 1.04 to 2.58. The 60 isolates were then subjected to screening for lignolytic activity by using methylene blue, azure B as indicator for bacteria and tannic acid as indicator for fungi. Out of them 11 bacterial isolates showed decolourisation of methylene blue and azure B and 4 fungal isolates were found to exhibit positive for tannic acid assay which is indication for lignolytic activity. Among these 60 isolates 3 bacterial isolates CD-5, PDS-3, and PDS-6 showed both cellulolytic and lignolytic activity.

Novel resources of chitinolytic bacteria isolated from Yok Don National Park, Vietnam.

This study focused on the isolation and characterization of chitinolytic bacteria from Yok Don National Park, Vietnam for future studies regarding biofertilizers and biocontrol agents. Chitinolytic bacteria were isolated from soils and chitin flakes soaked in river water at the National Park. On the basis of the halo zones caused by colloidal chitin degradation and colony morphologies, 12 chitinolytic strains were chosen from 15 700 isolates for various examinations. Findings from 16S rDNA analysis indicated that among these strains, 10 could be identified as different species, and the remaining 2 showed less identity to known species and genera. The 12 bacteria possess numerous properties concerning plant growth promotion and/or phytopathogenic biocontrol. Paenibacillus chitinolyticus YSY-3.1, which exhibited the highest chitinase activity and remarkable properties for plant growth, was chosen for sequencing and draft genome analysis. The results showed that the genome is 6571 781bp in length with 6194 coding sequences, 52.2% G+C, and 96.53% ANI value. It harbors the chitinolytic system comprising 22 enzymes. Among these enzymes, PcChiQ has a loop structure different from that of known family 19 chitinases, PcChiA contains two GH18 catalytic domains rarely found in microorganisms, and PcChiF contains three GH18 catalytic domains that have never been reported. The 12 identified chitinolytic bacteria exhibit great potential for further studies on plant growth-promoting and/or biocontrol properties. Among these bacteria, two strains might be good candidates for next examinations concerning novel species and/or genera, and strain YSY-3.1 could possess a novel chitinolytic system.

Isolation, characterization, and application of a novel, lytic phage vB_SalA_KFSST3 with depolymerase for the control of Salmonella and its biofilm on cantaloupe under cold temperature

This study investigated the efficacy of a novel Salmonella phage with depolymerase activity to control S. Typhimurium (ST) and its biofilm on cantaloupes, for the first time, under simulated cold temperature. vB_SalA_KFSST3 forming a halo zone was isolated and purified from a slaughterhouse with a final concentration of 12.1 ± 0.1 log PFU/mL. Based on the morphological and bioinformatics analyses, vB_SalA_KFSST3 was identified as a novel phage belonging to the family Ackermannviridae. Before employing the phage on cantaloupe, its genetic characteristics, specificity, stability, and bactericidal effect were investigated. Genetic analyses confirmed its safety and identified endolysin and two depolymerase domains possessing antibiofilm potential. In addition, the phage exhibited a broad specificity with great efficiencies toward five Salmonella strains at 4 °C, 22 °C, and 37 °C, as well as stable lytic activity over a wide range of pHs (3 to 11) and temperatures (−20 °C to 60 °C). The optimal multiplicity of infection (MOI) and exposure time of phage were determined to be 100 and 2 h, respectively, based on the highest bacterial reduction of ∼2.7 log CFU/mL. Following the formation of ST biofilm on cantaloupe at 4 °C and 22 °C, the cantaloupe was treated with phage at an MOI of 100 for 2 h. The antibiofilm efficacy of phage was evaluated via the plate count method, confocal laser scanning microscopy, and scanning electron microscopy (SEM). The initial biofilm population at 22 °C was significantly greater and more condensed than that at 4 °C. After phage treatment, biofilm population and the percentage of viable ST in biofilm were reduced by ∼4.6 log CFU/cm2 and ∼90% within 2 h, respectively, which were significantly greater than those at 22 °C (∼2.0 log CFU/cm2 and ∼45%) (P < 0.05). SEM images also confirmed more drastic destruction of the cohesive biofilm architecture at 4 °C than at 22 °C. As a result of its cold temperature-robust lytic activity and the contribution of endolysin and two depolymerases, vB_SalA_KFSST3 demonstrated excellent antibiofilm efficacy at cold temperature, highlighting its potential as a promising practical biocontrol agent for the control of ST and its biofilm.

The potency of soil bacteria on soil phosphorus solubilization and IAA production for innovation on sustainable Melon (Cucumis melo) production through biofilm biofertilizer

To fulfils the demand of melons (Cucumis melo), it requires intensive maintenance by agrochemical products. If this is done continuously, it will lead to soil degradation and disrupt the sustainable food supply. Therefore, an innovation is needed to maintain the sustainable food supply using biofilm biofertilizer technology. This study aims are to determine the potential of bacteria isolated from melon rhizosphere to solubilize phosphate and producing indole acetic acid (IAA) so that it can be developed into biofilm biofertilizer. Soil samples were taken from three melon gardens owned by farmers located in Sragen Regency, Karanganyar Regency and Wonogiri Regency, Central Java. In the laboratory, the soil bacteria then isolated from the soil using the dilution method. The isolates obtained then tested for their ability to solubilize phosphate and produce IAA. Phosphate is an essential nutrient for plant growth and IAA is plant growth promoting. The results showed that the highest phosphate solubilization potential was produced by bacterial isolate SRG 1A with a halo zone ratio of 1.957 and the highest concentration of IAA was produced by bacterial isolate WNG 1B with a value of 6.151 ppm. Based on the ability of the bacteria, indicates that the obtained bacterial isolates have the potential to be developed as a biofilm biofertilizer to help the growth of melon plants because it has the potency to solubilize soil nutrient and produce IAA.