Optimization of Production of Polyhydroxyalkanoates (PHAs) from Newly Isolated Ensifer sp. Strain HD34 by Response Surface Methodology

Petroleum-based plastics have become a big problem in many countries because of their non-degradability and that they become microplastics in the environment. This study focused on the optimization of production medium and conditions of polyhydroxyalkanoates (PHAs), which are biodegradable bioplastics and are accumulated in microbial cells. Among 341 isolates from 40 composted soil samples, the best isolate was the HD34 strain, which was identified using morphological, molecular, and biochemical methods. The results showed that the strain was most closely related to Ensifer adhaerens LMG20216T, with 99.6% similarity. For optimization of production medium and conditions using response surface methodology, it exhibited an optimal medium containing 3.99% (w/v) of potato dextrose broth (PDB) and 1.54% (w/v) of D-glucose with an adjusted initial pH of 9.0. The optimum production was achieved under culture conditions of a temperature of 28 °C, inoculum size of 2.5% (v/v), and a shaking speed of 130 rpm for 5 days. The results showed the highest PHA content, total cell dry weight, and PHA yield as 72.96% (w/w) of cell dry weight, 9.30 g/L, and 6.78 g/L, respectively. The extracted PHA characterization was studied using gas chromatography, 1H NMR, FTIR, and XRD. The results found that the polymer was a polyhydroxybutyrate (PHB) with a melting temperature (Tm) and degradation temperature (Td) of 173.5 °C and 260.8 °C, respectively

Inactivation of Contaminated Fungi in Rice Grains by Dielectric Heating

The quality of rice is decreased when contaminated with fungi. Aspergillus species are the most frequently found in rice. This research proposes using a dielectric heating method for fungal inactivation in rice grains by radio frequency (RF) energy. In order to understand the interaction between the fungi contaminating rice and electrical energy, dielectric properties comparison between Aspergillus sp. BP17 and rice powder were measured using an open-ended coaxial probe with a vector network analyzer (VNA) to develop dielectric heating equipment. The effect of RF energy on the dielectric heating system (9 kW, 40.68 MHz) is investigated based on different electric field intensities (150, 190, 225, 300, and 450 kV/m) with different temperatures (70, 80, 90, 100, and 110 °C). The growth of fungi contaminating rice was determined using a direct count method and reported as a percentage of inactivation. The result showed that the fungal inactivation of 100% was obtained at the electric field intensity value ≥ 225 kV/m at the lowest temperature of 90 °C. The combination of temperature and electric field intensity significantly (p ≤ 0.05) increased the percentage of fungal inactivation in rice grains. The optimal conditions of dielectric heating are suitable for fungal inactivation in rice industries. These results indicate that the proposed dielectric heating system is useful for inactivation of Aspergillus species

Response surface method for polyhydroxybutyrate (PHB) bioplastic accumulation in Bacillus drentensis BP17 using pineapple peel.

Polyhydroxybutyrate (PHB) is a biodegradable biopolymer which is useful for various applications including packing, medical and coating materials. An endospore-forming bacterium (strain BP17) was isolated from composted soil and evaluated for PHB production. Strain BP17, taxonomically identified as Bacillus drentensis, showed enhanced PHB accumulation and was selected for further studies. To achieve maximum PHB production, the culture conditions for B. drentensis BP17 were optimized through response surface methodology (RSM) employing central composite rotatable design (CCRD). The final optimum fermentation conditions included: pineapple peel solution, 11.5% (v/v); tryptic soy broth (TSB), 60 g/L; pH, 6.0; inoculum size, 10% (v/v) and temperature, 28°C for 36 h. This optimization yielded 5.55 g/L of PHB compared to the non-optimized condition (0.17 g/L). PHB accumulated by B. drentensis BP17 had a polydispersity value of 1.59 and an average molecular weight of 1.15x105 Da. Thermal analyses revealed that PHB existed as a thermally stable semi-crystalline polymer, exhibiting a thermal degradation temperature of 228°C, a melting temperature of 172°C and an apparent melting enthalpy of fusion of 83.69 J/g. It is evident that B. drentensis strain BP17 is a promising bacterium candidate for PHB production using agricultural waste, such as pineapple peel as a low-cost alternative carbon source for PHB production

Effective enhancement of polylactic acid-degrading enzyme production by <i>Amycolatopsis</i> sp. strain SCM_MK2-4 using statistical and one-factor-at-a-time approaches

<p>This study aims to find the optimal medium and conditions for polylactic acid (PLA)-degrading enzyme production by <i>Amycolatopsis</i> sp. SCM_MK2-4. Screening of the most effective components in the enzyme production medium by Plackett–Burman design revealed that the silk cocoon and PLA film were the most significant variables enhancing the PLA-degrading enzyme production. After an response surface methodology, a maximum amount of PLA-degrading enzyme activity at 0.74 U mL⁻¹ was predicted and successfully validated at 95% after 0.39% (w/v) silk cocoon and 1.62% (w/v) PLA film were applied to the basal medium. The optimal initial pH value, temperature, and inoculum size were evaluated by a method considering one-factor-at-a-time. The values were recorded at an initial pH in the range of 7.5–9.0, a temperature of 30–32°C, and an inoculum size of 4–10%. The highest activity of approximately 0.95 U mL⁻¹ was achieved after 4 days of cultivation using the optimized medium and under optimized conditions in a shake flask. Upscaling to the use of a 3-L stirred tank fermenter was found to be successful with a PLA-degrading activity of 5.53 U mL⁻¹; which represents a 51-fold increase in the activity compared with that obtained from the nonoptimized medium and conditions in the shake flask.</p

The amazing potential of fungi: 50 ways we can exploit fungi industrially

International audienceFungi are an understudied, biotechnologically valuable group of organisms. Due to the immense range of habitats thatfungi inhabit, and the consequent need to compete against a diverse array of other fungi, bacteria, and animals, fungi havedeveloped numerous survival mechanisms. The unique attributes of fungi thus herald great promise for their application inbiotechnology and industry. Moreover, fungi can be grown with relative ease, making production at scale viable. Thesearch for fungal biodiversity, and the construction of a living fungi collection, both have incredible economic potential inlocating organisms with novel industrial uses that will lead to novel products. This manuscript reviews fifty ways in whichfungi can potentially be utilized as biotechnology. We provide notes and examples for each potential exploitation and giveexamples from our own work and the work of other notable researchers. We also provide a flow chart that can be used toconvince funding bodies of the importance of fungi for biotechnological research and as potential products. Fungi haveprovided the world with penicillin, lovastatin, and other globally significant medicines, and they remain an untappedresource with enormous industrial potentia