Bakteri heterotrofik sangat berperan penting dalam sistem perairan karena kemampuan aktivitas metabolismenya. Bakteri tersebut berinteraksi dengan logam dan mineral dalam lingkungan alam dan sintetis, mengubah keadaan fisik dan kimianya sehingga mempengaruhi aktivitas, pertumbuhan dan kelangsungan hidup bakteri. Penelitian ini bertujuan untuk mengisolasi dan mengkarakterisasi bakteri resisten logam timbal (Pb) dan asam di Situ Cibintu, Cibinong, Jawa Barat. Sampel air diambil dari 3 titik di Situ Cibuntu dan dianalisis distribusi bakteri heterotrofiknya. Isolat bakteri dikultur di media Triptone Glucose Yeast (TGY). Selanjutnya dilakukan resistensi terhadap logam timbal (Pb) dan asam. Hasil penelitian menunjukkan bahwa jumlah bakteri heterotrof di Situ Cibuntu rata-rata 3,5x10 3 cfu m/L. Mayoritas (73%) isolat bakteri resisten terhadap logam timbal sebanyak 47% dan resisten terhadap asam (pH 4). Bakteri yang resisten didominasi oleh Gram negatif. Penelitian ini memberikan pengetahuan mengenai kemampuan adaptasi bakteri heterotrof pada lingkungan logam dan asam.
Aims:Bioplastic is a biodegradable polymer produced by particular microorganism as a secondary metabolite. Some halophilic bacteria belonging to Halomonas genus have been reported to be a potential of polyhydroxybutyrate (PHB) producer. This study aims to explore the potential of an indigenous halophilic bacterial isolate, H. elongata BK-AG18, as bioplastic producer. The indication as bioplastics producer was evaluated by growing in nile red-containing medium and bacterial colonies displayed bright orange fluorescent under ultraviolet light. Methodology and results: Bioplastic production by H. elongata BK-AG 18 was achieved using modified glucosecontained High Medium (HM) after incubated in a rotary shaker for 22 h, 37 °C, 150 rpm. The bioplastic was extracted with chloroform and sodium hypochlorite (1:1) and precipitated in methanol. The highest yield of bioplastic production was 21.36% of the dried bacterial cell weight. The structural characterizations of the bioplastics using Fourier transformed infrared (FTIR), 1 H and 13 C nuclear magnetic resonances (NMR) spectroscopies showed high similarity to the spectral pattern of polyhydroxybutyrate (PHB). Further characterization using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed that the decomposition and melting temperature at 266 °C and 166.5 °C of the PHB, respectively. The result of PHB has a low degree of crystallinity (9.5%) that close to the rubber-like polymer. Conclusion, significance and impact of study: This study revealed the high potential of H. elongata BK-AG 18 as PHB producer with high mechanical properties.
<span>Pollution of water environment with heavy metals is becoming one of the most severe environmental and human health hazards. Lead (Pb) is a major pollutant and highly toxic to human, animals, plants, and microbes. </span><span lang="IN">Toxic metals are difficult to remove from the environment, since they cannot be chemically or biologically degraded and are ultimately indestructible. Biological approaches based on metal-resistant microorganisms have received a great deal of attention as alternative remediation processes. </span><span>This study aim to isolat</span><span lang="IN">e</span><span> and characterize Pb resistant of heterotrophic bacteria in Cilalay Lake, </span><span lang="IN">West Java, </span><span>Indonesia. The water samples were collected </span><span lang="IN">along</span><span> three points around Cilalay Lake. </span><span lang="IN">Water physical and chemical </span><span>determination was performed using the Water Quality Checker</span><span lang="IN">. </span><span>The bacterial isolates were screened on T</span><span lang="IN">r</span><span>ipton</span><span lang="IN">e</span><span> Glucose Yeast (TGY) agar plates. </span><span lang="IN">Afterwards s</span><span>elected isolates were grown on Nutrient Agar media 50% </span><span lang="IN">with </span><span>supplemented Pb 100 ppm by the standard disk. Population of resistant bacteria was counted. The result from metal resistant bacteria indicated that all isolates w</span><span lang="IN">ere</span><span> resistant. The most abundant type of resistant </span><span lang="IN">bacteria </span><span>to lead was Gram negative more than Gram positive. Identified have metal resistant bacteria could be useful for the bioremediation of heavy metal contaminated sewage and waste water</span>
Background Pseudomonas putida as a cell factory is increasingly being used due to its remarkable features such as fast growth, versatile and robust metabolism, extensive genetic toolbox and high tolerance to oxidative stress and toxic compounds. This interest is driven by the need to improve microbial performance to a level that enables biologically possible processes to become economically feasible and thereby foster the transition from an oil-based economy to a more sustainable bio-based one. To this end, one of the current strategies is to maximize the product-substrate yield of an aerobic biocatalyst such as P. putida during growth on glycolytic carbon sources, such as glycerol and xylose. We demonstrate that this can be achieved by implementing the phosphoketolase shunt, through which pyruvate decarboxylation is prevented, and thus carbon loss is minimized. ResultsIn this study, we introduced the phosphoketolase shunt in the metabolism of P. putida KT2440. To maximize the effect of this pathway, we first tested and selected a phosphoketolase (Xfpk) enzyme with high activity in P. putida. Results of the enzymatic assays revealed that the most efficient Xfpk was the one isolated from Bifidobacterium breve. Using this enzyme, we improved the P. putida growth rate on glycerol and xylose by 44 and 167 %, respectively, as well as the biomass yield quantified by OD600nm by 50 and 30 %, respectively. Finally, we achieved 38.5 % and 25.9 % more mevalonate-glycerol and flaviolin-glycerol yield, respectively. A similar effect was observed on the mevalonate-xylose and flaviolin-xylose yields, which increased 48.7 and 49.4 %, respectively. ConclusionsP. putida with the Xfpk shunt grew faster, reached higher final OD600nm and provided better product-substrate yields. By reducing the pyruvate decarboxylation flux, we significantly improved the performance of this important workhorse for industrial applications. This work encompasses the first steps towards full implementation of the non-oxidative glycolysis (NOG) or the glycolysis alternative high carbon yield cycle (GATCHYC), in which a substrate is converted into products without CO2 loss These enhanced properties of P. putida will be crucial for its subsequent use in a range of industrial processes.
Background Pseudomonas putida has received increasing interest as a cell factory due to its remarkable features such as fast growth, a versatile and robust metabolism, an extensive genetic toolbox and its high tolerance to oxidative stress and toxic compounds. This interest is driven by the need to improve microbial performance to a level that enables biologically possible processes to become economically feasible, thereby fostering the transition from an oil-based economy to a more sustainable bio-based one. To this end, one of the current strategies is to maximize the product-substrate yield of an aerobic biocatalyst such as P. putida during growth on glycolytic carbon sources, such as glycerol and xylose. We demonstrate that this can be achieved by implementing the phosphoketolase shunt, through which pyruvate decarboxylation is prevented, and thus carbon loss is minimized. Results In this study, we introduced the phosphoketolase shunt in the metabolism of P. putida KT2440. To maximize the effect of this pathway, we first tested and selected a phosphoketolase (Xfpk) enzyme with high activity in P. putida. Results of the enzymatic assays revealed that the most efficient Xfpk was the one isolated from Bifidobacterium breve. Using this enzyme, we improved the P. putida growth rate on glycerol and xylose by 44 and 167%, respectively, as well as the biomass yield quantified by OD600 by 50 and 30%, respectively. Finally, we demonstrated the impact on product formation and achieved a 38.5% increase in mevalonate and a 25.9% increase in flaviolin yield from glycerol. A similar effect was observed on the mevalonate-xylose and flaviolin-xylose yields, which increased by 48.7 and 49.4%, respectively. Conclusions Pseudomonas putida with the implemented Xfpk shunt grew faster, reached a higher final OD600nm and provided better product-substrate yields than the wild type. By reducing the pyruvate decarboxylation flux, we significantly improved the performance of this important workhorse for industrial applications. This work encompasses the first steps towards full implementation of the non-oxidative glycolysis (NOG) or the glycolysis alternative high carbon yield cycle (GATCHYC), in which a substrate is converted into products without CO2 loss These enhanced properties of P. putida will be crucial for its subsequent use in a range of industrial processes.
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