Potential Of Bacterial Isolates Research Articles

Production of poly-(R)-3-hydroxybutyrate from halophilic bacterium Salinivibrio sp. utilizing palm oil mill effluent as a carbon source

The accumulation of plastic waste has become an emerging threat to the ecosystem. Reducing plastic waste can be overcome by replacing petrochemical-based plastics with biodegradable ones, such as poly-(R)-3-hydroxybutyrate (PHB). In the present study, we have successfully isolated, characterized, and optimized the PHB yield produced by halophilic bacteria isolated from salt lake Gili Meno, Lombok, Indonesia, utilizing palm oil mill effluent (POME) as the carbon source. Bacterial screening found that isolated bacteria from the bottom of the lake produced the highest PHB yield, mainly when the bacterial isolate was grown in the medium containing 15% (v/v) POME, 5% (w/v) NaCl, as well as 0.1% (w/v) yeast, and 0.1% (w/v) ammonium sulfate. The highest PHB yield produced by the bacterial isolate in this medium was about 5.0 ± 0.8 mg/L. Ribotyping has identified the bacterial isolate as Salinivibrio sp. with 99.9% similarity to the 16S rRNA gene of Salinivibrio sp. YCSC6 (GenBank accession no. CP039516.1). Scanning electron microscope images of the produced PHB exhibited the morphology of sheet-like structures. Thermal analysis revealed that the produced PHB has maximum decomposition and degradation temperatures at 442.4 °C and 282.9 °C, respectively. Therefore, Salinivibrio sp. is a potential bacterial isolate for producing high-yield PHB with high thermal stability. In addition, this bacterial strain is also a productive bacterium in bio-converting POME into PHB, thereby resolving the environmental issue of liquid waste from palm oil industries.

Biodegradation of Synthetic Dyes by Bacteria Isolated from Textile Industry Water Effluent

Aims: Biodegradation of synthetic dyes by bacteria isolated from textile industry water effluent.
 Study Design: Different bacterial strains were isolated from the water effluent generated by textile industry. These bacteria were identified using morphological and molecular characterization and their ability to degrade synthetic dyes was evaluated. The dyes used in this study were methylene blue, malachite green, congo red, and methyl red.
 Place and Duration of Study: Samples were collected from textile industrial area of Mandideep, Raisen (Madhya Pradesh, India). All the experiments were conducted in Department of Microbiology, Barkatullah University, Bhopal (Madhya Pradesh, India) between January 2019 to June 2019.
 Methodology: Textile dye effluent was collected from industrial area of Mandideep, Raisen (Madhya Pradesh, India). The collected effluent sample was analyzed for its physical characteristics (pH, temperature, colour, odour, electrical conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved oxygen (DO), turbidity, and total hardness). Different bacteria were isolated from this effluent using nutrient agar medium. These bacteria were screened for their ability to degrade synthetic dyes like methylene blue, malachite green, congo red, and methyl red. The potential bacterial isolates were identified using morphological and molecular methods and its ability to degrade synthetic dyes was estimated.
 Results: In the current study 24 bacterial isolates were isolated from the textile water and screened for their ability to degrade methylene blue, malachite green, congo red, and methyl red. The secondary screening revealed five bacterial isolates (R-1, R-2, R-6, R-8, and R-14) possess potential of degrading all four dyes. All the isolates were tested for genetic similarity using BOX-PCR which revealed isolates R-1, and R-2 to be similar, therefore four isolates R-1, R-6, R-8, and R-14 were selected for further study. Isolate R-14 effectively degraded 79.84% of methylene blue and 84.23% of methyl red at 200 mg/L respectively after 24 h. 89.3% of 100 mg/L malachite green dye was degraded by isolate R-14 in 72 h. Congo red dye at concentration 100 mg/L was degraded 88.96% by isolate R-8. R-1 and R-6 exhibited 71.1% and 74.6% degradation of methyl red dye respectively at 100 mg/L concentration. All the four potential isolates were identified using 16S r-RNA sequencing which revealed isolate R-1, R-6, R-8, and R-14 to be Pseudomonas geniculata, Bacillus altitudinis, Bacillus subtilis, and Citrobacter freundii respectively. This study reports effective degradation of synthetic dyes using bacterial isolates.
 Conclusion: The potential bacteria Pseudomonas geniculata, Bacillus altitudinis, Bacillus subtilis, and Citrobacter freundii can be industrially employed for the biodegradation of synthetic dyes.

Isolasi dan Seleksi Bakteri Kandidat Selulolitik dari Proses Pembuatan Pupuk Organik pada Pengolahan Limbah Peternakan

Cattle farming is one of the livestock business commodities in Indonesia. In the production process, cattle farms produce waste in the form of feces and leftover feed which can be processed in such a way through a decomposition process into organic fertilizer. The rate of the decomposition process is influenced by the existing decomposer microbes. One of the microbes needed in the decomposition process is cellulolytic bacteria. The research was conducted to obtain potential cellulolytic bacterial isolates from the compost which can then be used as a starter in the decomposition process. This research was conducted experimentally with the stages of research including isolation of bacteria from decomposers, the isolates obtained were then reviewed on Nutrient Agar media to produce uniform colonies. Furthermore, screening was carried out to obtain cellulolytic bacteria using NA media added with 1% CMC (Carboxymethyl Cellulose). Based on the results of the study, obtained 7 bacterial isolates that have various cellulolytic indices. The best cellulolytic index was produced by isolates NC-12, NC-17, and NC-16.

Hydrolysis of Cellulose Rich Agricultural Waste Using Two Potent Local Bacterial Isolates

Hydrolysis of Cellulose Rich Agricultural Waste Using Two Potent Local Bacterial Isolates

Xylanase from thermotolerant Bacillus haynesii strain, synthesis, characterization, optimization using Box-Behnken Design, and biobleaching activity

AbstractThe economic value of xylanolytic enzymes is derived from their use in a variety of industrial processes, which necessitates a cost-effective manufacturing procedure. In the current study, forty bacterial isolates were isolated from water samples and investigate their efficacy to producing xylanase enzyme. The most potent bacterial isolate was identified by sequencing and amplifications of 16Sr RNA gene as Bacillus haynesii strain K6. The impacts of various culture conditions on the productivity of xylane were examined. Data showed that the highest xylanase production was achieved at pH 7, in presence of 3 g/L xylan, 5 g/L peptone, and incubated at 40 °C for 24 h. The Box-Behnken model was used to find the best parameters for the relevant variables, and the results revealed an increase in xylanase production with values of 35.02 U/mL. The maximum precipitation of xylanase from the optimized culture was attained by ammonium sulfate (60%) followed by purification using dialysis and sephadex G100 column chromatography. The purified xylanase had a 12-fold enrichment, with a specific activity of 84 U/mg and a molecular weight approximately 439 KDa determined by thin-layer chromatography (TLC)/mass spectrometry. The amino acid analysis of the purified xylanase enzyme revealed the presence of 15 amino acids, with the highest concentrations of 1940 and 1520 mg/L for proline and cysteine, respectively. Finally, the physical properties of wastepaper pulp were improved after treatment with xylanase enzyme. The whiteness and softness of xylanase-treated wastepaper were improved with percentages of 34.6% and 16.2%, respectively. Therefore, we recommend the use of xylanase enzyme in the bleaching process as it is a biologically synthetic material, safe, and suitable for industrial use, and it reduces the use of harmful chemicals.

Crude oil hydrocarbon degradation efficiency of indigenous bacterial strains isolated from contaminated sites in Nigeria

The crude oil degradation potential of bacterial isolates from three contaminated sites in Nigeria were investigated. Seven bacterial isolates namely Pseudomonas aeruginosa strain W15, Pseudomonas aeruginosa strain N3R, Serratia marcescens strain N4, Providencia vermicola strain W8, Serratia marcescens strain W13, Pseudomonas aeruginosa strain W11 and Pseudomonas protegens strain P7 were isolated and identified using molecular methods. Isolates N4, N3 and W13 showed higher % total petroleum hydrocarbon (TPH) degradation of 79.26%, 78.96% and 78.69% respectively than W15, P7, W8 and W11 with % TPH degradation of 68.96%, 62.14%, 59.75% and 59.00% respectively. W13 showed the fastest degradation rate with 78.72% within the first 14 days of incubation; however, after the 14th day, there was no progressive change in % TPH. W11 showed degradation of wider range of hydrocarbon components originally in the crude oil as well as the complete degradation of most intermediates formed. The isolates showed good degradation potentials for bioremediation applications.

Analyses of the Heavy Metal Resistance Pattern and Biosorption Potential of an Indigenous Bacillus tropicus Strain Isolated from Arable Soil

Heavy metal contamination has a significant impact on the environment and is a matter of global concern. Microorganisms, particularly bacteria, have evolved specific resistance mechanisms to metabolize and convert heavy metals into less toxic forms. The primary goal of this study was to explore naturally occurring indigenous bacteria from arable land and investigate their role in the eco-friendly recovery of heavy metal pollutants from arable land. In this study, 18 heavy metal resistant bacterial isolates were obtained from the arable soil of Dakshin Dinajpur region of West Bengal, India. A potent bacterial isolate (Bacillus tropicus MCCC 1A01406), was obtained demonstrating resistance against multiple heavy metals like Pb, Cr, Cd, Cu, Ni, Fe, Zn, and Co. The effect of heavy metals on the growth kinetics, heavy metal uptake, and antibiotic susceptibility of the isolate was studied in detail. The isolate was found to be efficient in Pb uptake and demonstrated relatively higher biological Pb removal efficiency and capacity in comparison to other Bacillus strains reported in the literature. The Pb biosorption capability of the isolate was interpreted using Langmuir and Freundlich’s adsorption isotherms. The experimental data fitted well with the Langmuir model, suggesting monolayer type adsorption. The isolate also demonstrated resistance against antibiotics like doxycycline, nalidixic acid, kanamycin, imipenem, metronidazole, ceftriaxone, and amoxicillin.

Bacterial community structure and bacterial isolates having antimicrobial potential in shrimp pond aquaculture

Diseases outbreaks in pond aquaculture have resulted in huge losses to the aquaculture industry. The emergence of non-antimicrobial and environment friendly agents (probiotics) is the potential consideration for the healthy shrimp aquaculture. The present study was aimed to compare the bacterial community compositions in shrimp ponds and surrounding seawater, as well as isolate probiotic bacteria from the shrimp ponds. Based on the high-throughput of 16S rRNA gene sequencing, all sequences were assigned to 3584 unique operational taxonomic units (OTUs) at 97% similarity levels, which were affiliated with 24 phyla, 54 classes, 235 families, and 367 genera. The 10 most abundant phyla were Bacteroidota, Proteobacteria, Actinobacteriota, Planctomycetota, Cyanobacteria, Chloroflexi, Firmicutes, Desulfobacterota, Patescibacteria and Verrucomicrobiota. Notably, the alpha diversity (Shannon diversity) of shrimp ponds was significantly differences (P < 0.05) with that of surrounding seawater. There were 2498 and 791 unique OTUs in shrimp ponds and surrounding seawater, respectively. A total of 15 isolates were obtained in the culturable bacterial diversity, and the antibacterial activities were recorded for potential probiotic bacterial isolates against different tested bacterial isolates including pathogenic bacteria. An isolate Hallobacillusmarinus HMALI004 showed strong inhibitory effects against three pathogenic bacteria, Vibrio cholerae CECT 514, non AHPND V. parahaemolyticus BCRC12959 and AHPND V. parahaemolyticus PD-2. The isolates Algophigussanaruensis AGALI005, Algoriphagus taiwanensis ATALI009 and Bacillusaequororis BAALI008 were also identified as potential probiotics strains.

Optimization of nutritional and physical parameters for enhancing the keratinase activity of Bacillus cereus isolated from soil of poultry dump site in Gurugram, Haryana

Poultry waste especially feathers consists of over 90% proteins, which are primarily keratins. The enzyme assisted microbial degradation of keratins is a beneficial alternative to convert waste into value added products. In the present work, optimization of nutritional and physical parameters was achieved for Bacillus cereus strains to enhance the production of keratinases responsible for degradation of keratins present in feather waste. The results showed 2.29-fold increase in keratinase activity after optimization leading to 98.6 % degradation of feathers in 48 h for B. cereus strain H16 and 2.03 fold for strain H3 (2) resulting in 80.46 % degradation of feathers in 60 h. The study concluded that B. cereus H16 could be employed as potent keratinolytic bacterial isolate for processes involving conversion of keratinous waste into feed supplement and nitrogenous fertilizer.

The potential of endophytic bacteria to suppress bacterial leaf blight in rice plants

Abstract. Rahma H, Nurbailis, Busniah M, Kristina N, Larasati Y. 2021. The potential of endophytic bacteria to suppress bacterial leaf blight in rice plants. Biodiversitas 23: 775-782. Endophytic bacteria are potential as biocontrol agents against bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae in rice to support sustainable agriculture. This study aimed to select and characterize 22 endophytic bacteria isolated from healthy rice, determine their ability to promote plant growth and suppress bacterial leaf blight disease in rice and also identify potential endophytic bacterial isolates. The study was arranged in a Completely Randomized Design with 24 treatments and three repetitions. The treatments used in the current study consisted of Xanthomonas oryzae infected plants and treated with endophytic bacterial isolates; infected plants without endophytic bacteria treatment (positive control), non-infected plants (negative control). Identification of potential endophytic bacteria was performed based on 16S rRNA sequences. Three out of 22 bacterial isolates, i.e., LmB1, LmA6, and LmB2 were able to suppress bacterial leaf blight disease with severity levels of 35.82%, 23.78%, and 23.78%, respectively. Based on the rice plant growth parameters, three bacterial isolates (LmA6, LmB1, and LmB35) were able to increase the growth of rice plants with an average value of 69.56%, 56.51%, and 47.82%, respectively. Two bacterial isolates, i.e., LmB 1 and LmA6 suppress the development of bacterial leaf blight disease and increase the growth of rice plants. Based on DNA sequence comparisons of DNA fragments amplified by 16S rRNA related marker of the selected bacterial isolates and database, then LmA6, LmB2, LmB1, and LmB35 had similarities with Bacillus cereus MD152 (96.87%), Bacillus thuringiensis ATCC 10792 (98.20%), Ochrobactrum intermedium strain OI1 (97.52%), and Stenotrophomonas maltophilia strain A1w2 (97.92%), respectively. Our study revealed that the indigenous endophytic bacteria from rice plants could be potential biological agents for controlling bacterial leaf blight disease and increasing plant growth.

Effect of phosphate solubilizing bio-inoculants and vermicompost application on mineral uptake and growth of coffee (Coffea arbica L.) seedlings under greenhouse condition

Arabica coffee (Coffea Arabica L.) is an economically important crop with the highest export revenue in Ethiopia. This study was designed to evaluate the bacterial and fungal phosphate solublization efficacy and to determine yield attributes of coffee seedlings under glasshouse conditions. The study was conducted at Jimma Agricultural Research Center. The experiment was done with completely randomized design (crd) in three (3) replications. Three potent bacterial isolates viz., rchvcb1, RScB1.19 and RMaB2.11 and three potent fungal isolates viz., rscf1.19 rlvcf2 and rchvcf2 were obtained from Jimma University, Veterinary Medicine, Microbiology Laboratory. The three bacterial isolates were tested for antimicrobial resistance pattern and for their potential to serve as bio-control agents. All the bacterial isolates showed 100% resistance to all the six antimicrobials tested. The growth of pathogenic Fusarium xyloriodes was slightly inhibited by rscf1.19. Single inoculation of rscf1.19+Phosphate fertilizer and dual inoculation of rscf1.19 and rchvcb1 with P fertilizer significantly (p&lt;0.05) increased plant height, root length, stem girth, leaf number, leaf area, fresh and dry weights of coffee seedlings. However, all the treatments combined with vermicompost showed suppressive characteristics with no seedlings emergency at all. rscf1.19 and rchvcb1 can be recommended as bio-fertilizers after conducting necessary field trials in order to reduce the cost required for chemical fertilizers.

Response surface algorithm for improved biotransformation of 1,4-dioxane using Staphylococcus capitis strain AG

The present investigation reports the biotransformation of an endrocrine disrupting agent; 1,4-dioxane through bacterial metabolism. Initially, potential bacterial isolates capable of surviving with minimum 1,4-dioxane were screened from industrial wastewater. Thereafter, screening was done to isolate a bacteria which can biotransform higher concentration (1000 mg/L) of 1,4-dioxane. Morphological and biochemical features were examined prior establishing their phylogenetic relationships and the bacterium was identified as Staphylococcus capitis strain AG. Biotransformation experiments were tailored using response surface tool and predictions were made to elucidate the opimal conditions. Critical factors influencing bio-transformation efficiency such as tetrahydrofuran, availability of 1,4-dioxane and inoculum size were varied at three different levels as per the central composite design for ameliorating 1,4-dioxane removal. Functional attenuation of 1,4-dioxane by S. capitis strain AG were understood using spectroscopic techniques were significant changes in the peak positions and chemical shifts were visualized. Mass spectral profile revealed that 1.5 (% v/v) S. capitis strain AG could completely (∼99%) remove 1000 mg/L 1,4-dioxane, when incubated with 2 μg/L tetrahydrofuran for 96 h. The toxicity of 1,4-dioxane and biotransformed products by S. capitis strain AG were tested on Artemia salina. The results of toxicity tests revealed that the metabolic products were less toxic as they exerted minimal mortality rate after 48 h exposure. Thus, this research would be the first to report the response prediction and precise tailoring of 1,4-dioxane biotransformation using S. captis strain AG.

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.

Co-Inoculation of Bacillus spp. for Growth Promotion and Iron Fortification in Sorghum

Seven Bacillus spp. isolated from the marine water and the rhizosphere of the medicinal plant Coscinium fenestratum were studied to produce plant growth promotion (PGP) traits invitro. Among the seven isolates, MMRH22 and RHPR20 produced copious amounts of PGP traits. Based on the 16S rRNA sequence, the two potent bacterial isolates, RHPR20 and MMRH22, were identified as Bacillus mojavensis and Bacillus cereus, respectively. A compatibility test between the isolates RHPR20 and MMRH22 revealed they are compatible and can be used as a consortium. Both isolates were evaluated for the plant growth promotion and the biofortification of sorghum under greenhouse conditions. Treatments included the application of MMRH22, RHPR20, their consortium (RHPR20 + MMRH22), and an uninoculated control. Inoculation with bacterial cultures resulted in a significant increase in the plant height; the number of leaves; the leaf area; the root, shoot, and leaf weight; and the yield of sorghum at 30 and 60 days after sowing (DAS). The scanning electron micrograph of the sorghum plant roots revealed extensive colonization in the plants treated with the bacterial cultures compared to the uninoculated control. The sorghum grains obtained after final harvest were analyzed for their nutrient content by ICP–OES. The biofortification in sorghum grains was varied and was found to enhance the iron content up to 97%. This study revealed that treatments with microbial consortia enhance plant growth, yield, and iron content, which could combat nutrient deficiencies in plants and humans.

Screening of plant growth-promoting bacterial endophytes and rhizobacteria isolated from Curcuma xanthorrhiza

Bacterial endophyte and rhizobacteria were reported to associate with medicinal plants including Zingiberaceae plants and involved in growth promotion. These beneficial bacteria are promising candidates as biostimulants because of their ability in promoting plant growth. This study aims to evaluate the activity of endophytic and rhizosphere bacteria isolated from Curcuma xanthorrhiza (Javanese turmeric) in promoting rice seedling and Javanese turmeric growth. Fifty-seven of 150 total bacterial isolates with negative hemolysis and hypersensitivity reactions were characterized to investigate their plant growth-promoting (PGP) traits. Ten selected bacteria (two bacterial endophytes and eight rhizobacteria) with multiple PGP traits were inoculated to rice seed with seed treatment and inoculated to Javanese turmeric rhizome with seed treatment and seed treatment+soil soil drenching. Our results showed that bacterial isolates tested on rice seed promoted rice seedling growth significantly. A total of five, three, six, and three bacterial isolates could increase leaf number, root length, fresh shoot weight, and fresh root weight of rice seedling (p<0.05), respectively. In contrast, all of the bacterial isolates tested on Javanese turmeric rhizomes showed a non-significant effect on the plant growth. Further studies should be considered to investigate the effect of formulated potential bacterial isolates with different application frequencies and environmental conditions on the harvest yield of rice and Javanese turmeric as well as active compounds of Javanese turmeric.

Production of eco-friendly PHB-based bioplastics by Pseudomonas aeruginosa CWS2020 isolate using poultry (chicken feather) waste.

Nowadays, the accumulation of non-degradable plastics and other disposed wastes leads to environmental pollution across the world. The production of eco-friendly and cost-effective poly-β-hydroxybutyrate (PHB) could be a better alternative to conventional petroleum-based plastics and prevent environmental pollution. Besides, the area in and around Namakkal, Tamil Nadu, India is well known for poultries, currently facing the number of environmental issues due to the accumulation of chicken feather waste. This study focused on the production of eco-friendly PHB by recycling poultry (chicken feather) waste as the substrate. The native PHB producers were screened from the chicken waste disposal site in Namakkal by Sudan black B staining method. Further, the potent bacterial isolate was identified as Pseudomonas aeruginosa (NCBI accession MF18889) by phenotypic and genotypic characteristics. The PHB production media with chicken feather waste was statistically optimized by response surface methodology. The dry weight of PHB produced under optimized condition (15.96g/L chicken feather waste, 37°C temperature, 19.8g/L glucose and 6.85 pH) was found to be 4.8g/L. Besides, PHB was characterized and confirmed by thin-layer chromatography, Fourier-transform infrared spectroscopy and Gas chromatography-mass spectrometry analysis. Thus, this study concludes that poultry waste could be a complex nitrogen source for improving the growth of PHB producers and substantially increasing the yield of PHB, and it will be an eco-friendly and low-cost production in bioprocess technology.

Aktivitas Antibakteri Isolat Bakteri Endofit Tanaman Kunyit (Curcuma longa L.) Terhadap Pertumbuhan Staphylococcus aureus

Staphylococcus aureus is a commensal bacterial of the body that can become pathogen at any time. Along with the increase of antibacterial resistant cases, it is necessary to explore the new potential metabolites as antibacterial. Endophytic bacteria that live on turmeric (Curcuma longa L.) are thought to be able to produce secondary metabolites that are similar and even more varied than their host plants.To determine the antibacterial effect of secondary metabolite compounds of turmeric (Curcuma longa L.) endophytic bacteria on Staphylococcus aureus. Endophytic bacterial isolates were subcultured on NA media with a streak plate method. Antibacterial activity test useds disk diffusion method. Potential endophytic bacterial isolates were characterized based on colony morphology, cell morphology and biochemical properties and secondary metabolite compounds produced are identified with a ciulei method. A total of 17 endophytic bacterial isolates were successfully subcultured. All endophytic bacterial isolates had antibacterial activity range from 7.4-13.76 mm. One of the most potential isolates was M8 isolate which had similarity with a genus Pseudomonas. The secondary metabolites that was produced bt M8 isolates were alkaloids, terpenoids and saponins. The most potential endophytic bacteria as antibacterial belong to the genus Pseudomonas and had alkaloids, terpenoids and saponins.

Enhanced removal of fifteen pesticide mixture by a single bacterial strain using response surface methodology and its application in raw milk.

Environmental contamination with various pesticides accompanied by uncontrolled use contributes to severe ecological and health problems. Although extensive research was conducted on pesticides degradation, very few reports have demonstrated the degradation of mixed pesticides. Consequently, this study aimed to evaluate the removal efficacy of highly potent bacterial isolate for pesticide mixture under optimal culture conditions, followed by their application in milk. Isolation and selection of bacterial isolates were performed from 40 milk samples by enrichment culture technique and were screened to obtain highly potent bacterial strain identified by 16 S rDNA analysis. The statistics-based experimental designs were applied to optimize the culture conditions towards the best degradation of pesticides mixture, followed by subsequent utilization in milk. The degradation ratio of pesticides was analyzed using gas chromatography-mass spectrometry. In this study, a bacterial strain S6A identified as Bacillus subtilis-mw1 efficiently eliminated environmental contaminants from different groups of pesticide residues. The statistical optimization showcased optimum settings that accomplished the highest pesticide mixture degradation (61.59 %). The application experiment manifested that degradation of pesticide mixtures of sterile milk (STM) was relatively faster than non-sterile milk (NSTM). The obtained results assist in eliminating environmental contamination with various groups of pesticide residues. Furthermore, it can be employed in reducing pesticide residues that cause milk contamination to increase safety and quality.Graphical abstract. The online version contains supplementary material available at 10.1007/s40201-021-00683-0.

Isolation and Identification of Cellulolytic Bacteria Symbiont from Various Termites on Different Nest Type in Bukit Baka Bukit Raya National Park, West Kalimantan, Indonesia

The microbial symbiotic community in the digestive tract of termites is reportedly influenced by the taxonomy and feeding habit of the host. Both factors are strongly correlated with the nest type. This study aimed to isolate the cellulolytic bacteria from termite’s digestive tract on different nest types and characterize and identify the potential isolates. The research methods included termite sampling conducted in Bukit Baka Bukit Raya National Park (BBBRNP), Melawi, West Kalimantan, isolation of cellulolytic bacteria from termites’ gut, endoglucanase activity test, biochemical characterization, and DNA analysis based on the amplification of 16S rRNA gene. Thirty isolates from 6 different species of termites on three different nest types were successfully isolated. Sixteen potential endoglucanase bacterial isolates were tested in terms of their endoglucanase activity. The cellulolytic index measured from those isolates ranged from 1.162 - 4.894. Three isolates (MRH.13.S, MRH.13.AF, and MRH.13.O2) with the highest cellulolytic index on each nest type were identified. The analysis of 16S rRNA gene using BLAST (Basic Local Alignment Search Tool for Nucleotides) revealed that isolate MRH.13.S had the closest relationship with Bacillus tequilensis (99 % homology). Based on biochemical characterization, MRH.13.AF and MRH.13.O2 isolates were related to Bacillus spp. HIGHLIGHTS Potential cellulolytic bacteria from termite intestinal tract from different nests (i.e., soil, wood, and arboreal) were isolated and compared Termites were obtained from a lowland dipterocarp primary forest ecosystem in Bukit Baka Bukit Raya National Park, West Kalimantan Province, Indonesia Termite species collected were Termes comis, Dicuspiditermes garthwaitei, Synhamitermes quadriceps, Havilanditermes proatripennis, Bulbitermes borneensis, and Bulbitermes parapusillus Potential cellulolytic bacteria acquired were closely related with Bacillus tequilensis and Bacillus spp GRAPHICAL ABSTRACT

Bioremediation of polyvinyl chloride (PVC) films by marine bacteria

Polyvinyl chloride (PVC) is the third one after polyethylene and polypropylene in the production demand. It intends to grow further, causing an increase in the risk of health and ecological problems due to environmental accumulation and incineration. In the present study, we determined the biodegradative abilities of marine bacteria for PVC. Three potential marine bacterial isolates, T-1.3, BP-4.3 and S-237 (Vibrio, Altermonas and Cobetia, respectively) were identified after preliminary screening. They led to active biofilm formation, viability and protein formation on the PVC surface. The highest weight loss (1.76%) of PVC films was exhibited by BP-4.3 isolate after 60 days of incubation. Remineralization of PVC film was confirmed by CO2 assimilation assay. Change in surface topography was confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The functional group peak intensity was decreased for the terminal chlorine group at the region 1000–1300 cm−1, which indicated the dechlorination. Thermogravimetric, tensile strength and contact angle analysis showed a decline in the mechanical properties and a rise in PVC film's hydrophilic nature after biodegradation. These results demonstrated promising evidence of PVC degradation by marine bacteria.