Mitigation of Commercial Food Waste-Related Salinity Stress Using Halotolerant Rhizobacteria in Chinese Cabbage Plants

The use of commercial food waste in the Korean agricultural industry is increasing due to its capacity to act as an ecofriendly fertilizer. However, the high salt content of food waste can be detrimental to plant health and increase salinity levels in agricultural fields. In the current study, we introduced halotolerant rhizobacteria to neutralize the negative impact of food waste-related salt stress on crop productivity. We isolated halotolerant rhizobacteria from plants at Pohang beach, and screened bacterial isolates for their plant growth-promoting traits and salt stress-mitigating capacity; consequently, the bacterial isolate Bacillus pumilus MAK9 was selected for further investigation. This isolate showed higher salt stress tolerance and produced indole-3-acetic acid along with other organic acids. Furthermore, the inoculation of B. pumilus MAK9 into Chinese cabbage plants alleviated the effects of salt stress and enhanced plant growth parameters, i.e., it increased shoot length (32%), root length (41%), fresh weight (18%), dry weight (35%), and chlorophyll content (13%) compared with such measurements in plants treated with food waste only (control). Moreover, relative to control plants, inoculated plants showed significantly decreased abscisic acid content (2-fold) and increased salicylic acid content (11.70%). Bacillus pumilus MAK9-inoculated Chinese cabbage plants also showed a significant decrease in glutathione (11%), polyphenol oxidase (17%), and superoxide anions (18%), but an increase in catalase (14%), peroxidase (19%), and total protein content (26%) in comparison to the levels in control plants. Inductively coupled plasma mass spectrometry analysis showed that B. pumilus MAK9-inoculated plants had higher calcium (3%), potassium (22%), and phosphorus (15%) levels, whereas sodium content (7%) declined compared with that in control plants. Similarly, increases in glucose (17%), fructose (11%), and sucrose (14%) contents were recorded in B. pumilus MAK9-inoculated plants relative to in control plants. The bacterial isolate MAK9 was confirmed as B. pumilus using 16S rRNA and phylogenetic analysis. In conclusion, the use of commercially powered food waste could be a climate-friendly agricultural practice when rhizobacteria that enhance tolerance to salinity stress are also added to plants.

Isolation and characterization of α ‐amylase encoding gene in Bacillus amyloliquefaciens PAS

Amylolytic bacteria are a source of amylase, which is an essential enzyme to support microalgae growth in the bioreactor for microalgae culture. In a previous study, the highest bacterial isolate to hydrolyze amylum (namely PAS) was successfully isolated from Ranu Pani, Indonesia, and it was identified as Bacillus amyloliquefaciens. That bacterial isolate (B. amyloliquefaciens PAS) also has been proven to accelerate Chlorella vulgaris growth in the mini bioreactor. This study aims to detect, isolate, and characterize the PAS’s α‐amylase encoding gene. This study was conducted with DNA extraction, amplification of α‐amylase gene with polymerase chain reaction (PCR) method with the specific primers, DNA sequencing, phylogenetic tree construction, and protein modeling. The result showed that α‐amylase was successfully detected in PAS bacterial isolate. The α‐amylase DNA fragment was obtained 1,468 bp and that translated sequence has an identity of about 98.3% compared to the B. amylolyquefaciens α‐amylase 3BH4 in the Protein Data Bank (PDB). The predicted 3D protein model of the PAS’s α‐amylase encoding gene has amino acid variations that predicted affect the protein’s structure in the small region. This research will be useful for further research to produce recombinant α‐amylase.

Biosurfactant-Producing Bacteria Isolated from Oil Contaminated Soil and its Media Optimization for Enzyme Production

Oil bio-degradation mechanism by microorganisms is requested for an effective microbial remediation of soil contamination by oil spills. The current examination pointed the identification of a biosurfactant producing bacteria for biosurfactant production from oil contaminated sites from Tamil Nadu. The biosurfactant testing screening methods were used to screen the potent strains and sequencing studies were used for Pseudomonas species identification. The bacterial isolate BS17 subjected to be the potent enzyme (Protease, Lipase and Esterase) producer. Among the tested production media, the ground nut oil cake was identified to be the optimum media for protease (0.47069 Unit/ml), lipase (9 Unit/ml) and esterase activity (3.891 Unit/ml) for bacterial isolate BS17. The bacterial isolate BS17 showed greatest lipase (15 Unit/mL) protease (0.8067 Unit/mL) and esterase (4.756 Unit/mL) enzyme activity at pH 9.0. At 35 ℃ bacterial isolate BS17 showed greatest enzyme action in protease (1.2772 Unit/mL), lipase (17 Unit/mL) and esterase (5.2972 Unit/mL) enzyme activity. At 48hrs of incubation period bacterial isolate BS17 showed most extreme enzyme activity in protease (3.361 Unit/mL), lipase (28 Unit/mL) and esterase (8.918 Unit/mL). The sequence of BS17 was deposited in NCBI and Accession number was received [MT337593.1]. Statistical analysis with the minimum significant difference (LSD) test of ANOVA was carried out to determine the oil degradation efficiency. This paper demonstrated the isolated P. aeruginosa (BS17) crude oil biodegradation from oil contaminated land soil sample. Strain BS17 was proved as potent bio-surfactant producer using crude oil by utilizing carbon and energy source in oil degradation mechanism.

Induction of Systemic Resistance in Tomato Plants Against Tomato yellow leaf curl virus in Protected Cultivation Using a Local Bacterial Isolate of Bacillus subtilis

Ghanem, H.M., E.H. Akel, Q.A. Al-Rhayeh and I.D. Ismail. 2021. Induction of Systemic Resistance in Tomato Plants Against Tomato yellow leaf curl virus in Protected Cultivation Using a Local Bacterial Isolate of Bacillus subtilis. Arab Journal of Plant Protection, 39(4): 289-295. https://doi.org/10.22268/AJPP-039.4.289295 This study was conducted at the Agricultural Scientific Research Center in Lattakia Governorate in a plastic house during the 2020/2021 growing season to evaluate the efficiency of the native bacterial isolate B.Ra.217 of Bacillus subtilis, in reducing infection of tomato plants with Tomato yellow leaf curl virus (TYLCV), by treating tomato seeds and later watering the seedlings with a suspension of the tested bacteria at a concentration of 1x109 /ml, and then measuring incidence (%) and severity of virus infection, and estimating peroxidase enzyme activity. The results showed that 30 days after inoculation with tomato leaf curl virus, a decrease in virus infection rate and severity in virus-infected and bacteria-treated plants compared with virus-infected and untreated control plants was observed. The reduction in disease incidence and severity of infection reached 26.67% and 34.28%, respectively, with significant differences between the treatments. In addition, the activity of peroxidase enzyme 7 days after infection with the virus showed an increase in plants treated with bacteria only (0.1342 μmol/mg) and those treated with bacteria and virus-infected (0.0913 μmol/mg), compared with the healthy control plants (0.0958 μmol/mg), and virus-infected and untreated with bacteria (0.0570 µmol/mg). The results also showed 15 days after infection that the enzyme activity was higher in plants treated with bacteria only (0.1592 µmol/mg) compared with the healthy control (0.1415 µmol/mg) with significant differences, and also the differences were significant with the untreated infected plants (0.1002 µmol/mg), and with inoculated and treated plants (0.1372 µmol/mg). Thus, this bacterial isolate may have an important applied role in enhancing tomato plant resistance to the virus and consequently reducing its damage. Keywords: Bacillus subtilis B.Ra.217, TYLCV, peroxidase, incidence, severity of infestation, tomato plant

Exploring bioactive pigments from marine bacterial isolate from the Indonesian seas

Marine microbes offer a significant source for biodiscovery due to their rich biodiversity and genetic capacity. Particularly, microbial pigments of marine origin are getting more attention in current research due to their widely perceived application as natural food colorants, antioxidant, antimicrobial, and many more. In the past five years, our research group has successfully characterised various bioactive pigments isolated from marine bacteria, including Erythrobacter flavus strain KJ5 that produces unique sulphur-containing carotenoids, Pseudoalteromonas rubra strain PS1 and SB14 that contain antimicrobial prodiginine, and Seonamhaeicola algicola strain CCI for high content of zeaxanthin. This paper describes the challenges we encountered in conducting research in exploring bioactive pigments especially with focus on carotenoid research, reviewed critically on strategy we developed for isolation of isolate as well as identification and elucidation of the pigments, and consideration for future research.

Isolation and Characterization of Photorhabdus Spp. (Enterobacteriaceae) Isolated From Heterorhabditis Bacteriophora in Kashere, Nigeria

Photorhabdus bacteria are symbiotically associated with the infective juveniles of entomopathogenic nematodes of the genus Heterorhabditis. These bacteria after infecting a susceptible host, produces a host of lethal toxins that killthe insect hosts within 24 to 72 hours. Consequently they have emerged and are trending as excellent biological control agents against insect pests of agricultural crops. Therefore, this study aim to isolate, identify and test the pathogenicity of Photorhabdus bacteria isolated from Heterorhabditis bacteriophora, entomopathogenic nematode from Kashere, Gombe State, Nigeria. To this end phenotypic and biochemical tests were conducted. The tests conducted showed that the isolate exhibited characteristics similar to those of Photorhabdus bacteria that have been identified. Last instar larvae of G. mellonella exposed to different concentrations of the bacterial isolate showed some level of susceptibility of the larvae to the bacterial isolate confirming its biological control potential.

Bioethanol production from pineapple peels waste by heat treatment and enzyme hydrolysis: An eco-friendly and economical method

Bioethanol is a renewable energy source with reduced CO2 emission and a better alternate for fossil fuels. The production of bioethanol using low cost agricultural wastes such as fruits waste always remains a better solution for the present environmental and energy problems. The present study focusses on the production of bioethanol from pineapple peel wastes by simultaneous scarification and fermentation process in a completely eco-friendly manner and economical manner. The fruit wastes are rich sources of sugars and can be utilized for the production of second generation fuel. Initially, cellulase producing potent bacterial isolate was isolated from soil sample collected from fruit market (Uzhavar Santhai), R.S. Puram, Coimbatore district, Tamilnadu, India. Further, the bacterial isolate was identified by 16S rDNA sequencing and the sequence was submitted in GenBank with the accession number MW227436. The phylogenetic tree was constructed and the bacterial isolate was identified as Bacillus cereus strain JK79. Pineapple peel waste was processed, heat pretreated and was utilized for enzymatic saccharification with crude cellulase enzyme to hydrolyze cellulose into simple sugars. The enzyme hydrolyzed content was allowed to undergo fermentation simultaneously (Simultaneous saccharification and fermentation) utilizing Saccharomyces cerevisiae to produce bioethanol. The yield of bioethanol was determined by potassium dichromate method. About 10.07 g/l of bioethanol was obtained by fermenting the enzymatically hydrolyzed pineapple peel waste using Saccharomyces cerevisiae. The production of bioethanol was confirmed by GC-MS.

Establishing and Quantifying the Phosphate Solubilizing Potential of the Brinjal Bacterial Isolate

Rhizosphere, phylloplane and caulosphere is the region where a complex community of microbes, mainly bacteria and fungi are present. The microbe plant interaction in these regions can be beneficial, neutral, variable, or deleterious for plant growth. The bacteria that exert beneficial effects on plant development are termed plant growth promoting bacteria. To quantify the amount of phosphate solubilizing bacteria from rhizosphere, phylloplane and caulosphere of brinjal (Solanum melongena L.). Materials and methods: Brinjal (Solanum melongena L.) plants of different varieties were collected from seven locations around Bangalore viz., Hessaraghatta, Yelahanka, Kengeri, Madi vala, Hebbal, Tirumalapura and Attibele were also screened for the presence of phosphate solubilizing bacteria. Nitrogenase activity was estimated by acetylene reduction assay and analyzed by gas chromatography. The amount of nitrogen fixed brinjal bacterial isolate was quantified by micro Kjeldhal method. The amount of nitrogen fixed by the BBI was equivalent to 23.5 nm of C2H2 reduced/tube/hour. The amount of nitrogen fixed by the BBI showed a steady increase upto three days (75 nm of C2H2 reduced/tube/hour) after which there was a decline in the amount of nitrogen fixed by the microbe. Phosphate solubilization by the bacteria isolated from brinjal is highly beneficial to the crop, as it would always make more phosphate available to the crop. This phosphate solubilizing potential could be harnessed to reduce the input of inorganic fertilizers. For the first time the presence of phosphate solubilizing bacteria on the rhizosphere and endorhizosphere of brinjal (Solanum Melongena L.) cultivars was established.

Enhanced Antioxidant Activity of Nano-Selenium Produced Using a Bacterial Isolate Citrobacter sp.

Selenium is essential for human, plant, and animal growth and reproduction. Because of their biological activity, bioavailability, and low toxicity, selenium nanoparticles are regarded as a promising material for many applications in biomedicine and health. Selenium-resistant bacteria were isolated from garden soil and identified as Citrobacter amalonaticus strain ARB01. TEM, UV-visible spectrophotometer, FTIR, and EDAX were used to characterize biosynthesized SeNPs using the cell-free extract of ARB01. The antioxidant activity of biologically functionalized SeNPs was evaluated using the 1, 1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant strength (FRAP), and 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The Dot-blot test was used to perform a qualitative study of the antioxidant activity of SeNPs using the TLC-DPPH technique. The TEM analysis revealed spherical SeNPs with diameters ranging from 50 nm to 80 nm. Because of the synergistic effect of biomolecules involved in nanoparticle synthesis, SeNPs showed higher antioxidant activity. This study reveals that the antioxidant activity of nanoparticles increased due to functionalization by biomolecules present in the cell-free extract of bacterial isolate.