Production of L-glutaminase From Agro-industrial Waste by Halomonas Elongata MM-5 Under Solid State Fermentation

In this study L-glutaminase production by extremely halotolerant Halomonas elongata MM-5 using solid-state fermentation was investigated. Screening of a variety of agro-industrial byproducts such as rice husk, green gram husk, bengal gram husk, red gram husk, safflower oil cake, groundnut oil cake, black gram husk, groundnut skin and wheat bran was carried out individually and in different combinations. Optimization of various physicochemical parameters namely incubation time, pH, temperature, initial moisture content, carbon sources, nitrogen sources, L-glutamine concentration and inoculum level was carried out. Among the various substrates screened individually red gram husk supported the maximum production of enzyme 79.03±0.49 IU/gds. In the mixture of substrates screened red gram husk and bengal gram husk in the ratio (60:40) showed maximum 92.06±1.42 IU/gds enzyme production. The L-glutaminase production was maximum after 4 days of incubation period, pH 8, temperature 40°C and 80 percent moisture content. The lactose and malt extract used as carbon and nitrogen sources respectively supported the maximum yield of L-glutaminase. After screening and optimization of various parameters, the yield of L-glutaminase increased from 79.03 to 159.12 IU/gds.

Efficient Amino Donor Recycling in Amination Reactions: Development of a New Alanine Dehydrogenase in Continuous Flow and Dialysis Membrane Reactors

Transaminases have arisen as one of the main biocatalysts for amine production but despite their many advantages, their stability is still a concern for widespread application. One of the reasons for their instability is the need to use an excess of the amino donor when trying to synthesise amines with unfavourable equilibria. To circumvent this, recycling systems for the amino donor, such as amino acid dehydrogenases or aldolases, have proved useful to push the equilibria while avoiding high amino donor concentrations. In this work, we report the use of a new alanine dehydrogenase from the halotolerant bacteria Halomonas elongata which exhibits excellent stability to different cosolvents, combined with the well characterised CbFDH as a recycling system of L-alanine for the amination of three model substrates with unfavourable equilibria. In a step forward, the amino donor recycling system has been co-immobilised and used in flow with success as well as re-used as a dialysis enclosed system for the amination of an aromatic aldehyde.

Nanotribological Investigation of the Poly(3-hydroxybutyrate) Films Manufactured from the Storage Polyesters Produced by Halomonas elongata DSM 2581T

Poly(3-hydroxybutyrate) (PHB) is a natural and biodegradable storage polyester, produced by numerous bacteria, which is considered a potential substituent for conventional plastics in the packaging industry. The improvement of the PHB material lifetime often involves mechanical and tribological characterization, which can be accurately performed on thin films. In this study, we aimed at the evaluation of the tribological properties, such as adhesion force, friction coefficient and wear resistance, of different polyester films, fabricated via the solvent casting method. Three polyester films were designed in this study, each containing 1% w/v constituents as follows: a PHBh film prepared out of the PHB, extracted from the extremely halotolerant bacteria, Halomonas elongata DSM2581T, a PHBc film fabricated using a commercially available PHB, and a PHBVc film generated using the commercial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The spectroscopy-in-point of AFM was used for adhesion force measurement based on multiple tests performed in a matrix, and the AFM lateral operating mode was applied for friction analysis under a controlled normal load. The fabricated PHBh film presented a thickness between 5 and 7 µm, a lower adhesion force (14 nN) as well as a smaller friction coefficient (0.15) compared to the PHBc and PHBVc. The tribological investigations of PHBh film revealed a biodegradable material with low roughness, as well as small adhesion and friction forces. Further optimization can be performed for the improvement of the PHBh film by copolymerization with other polymers, polyesters, and reinforcers, thus generating a feasible material with advanced tribo-mechanical features.

Microbial production of ectoine and hydroxyectoine as high-value chemicals

Ectoine and hydroxyectoine as typical representatives of compatible solutes are not only essential for extremophiles to survive in extreme environments, but also widely used in cosmetic and medical industries. Ectoine was traditionally produced by Halomonas elongata through a “bacterial milking” process, of which the marked feature is using a high-salt medium to stimulate ectoine biosynthesis and then excreting ectoine into a low-salt medium by osmotic shock. The optimal hydroxyectoine production was achieved by optimizing the fermentation process of Halomonas salina. However, high-salinity broth exacerbates the corrosion to fermenters, and more importantly, brings a big challenge to the subsequent wastewater treatment. Therefore, increasing attention has been paid to reducing the salinity of the fermentation broth but without a sacrifice of ectoine/hydroxyectoine production. With the fast development of functional genomics and synthetic biology, quite a lot of progress on the bioproduction of ectoine/hydroxyectoine has been achieved in recent years. The importation and expression of an ectoine producing pathway in a non-halophilic chassis has so far achieved the highest titer of ectoine (~ 65 g/L), while rational flux-tuning of halophilic chassis represents a promising strategy for the next-generation of ectoine industrial production. However, efficient conversion of ectoine to hydroxyectoine, which could benefit from a clearer understanding of the ectoine hydroxylase, is still a challenge to date.

Pengaruh Jenis Sumber Nitrogen Pada Produksi Biosurfaktan Oleh Bakteri Halofil

Bakteri halofil merupakan bakteri yang membutuhkan NaCl untuk pertumbuhannya. Salah satu potensi bakteri halofil adalah dapat menghasilkan biosurfaktan yang aktif pada konsentrasi garam yang tinggi. Oleh karena itu, biosurfaktan tersebut dapat diaplikasikan dalam industri minyak terutama pada bidang enhanced oil recovery (EOR). Selain itu, biosurfaktan diketahui secara luas diaplikasikan dalam industri farmasi dan makanan. Sifatnya yang lebih ramah lingkungan dibandingkan dengan surfaktan sintetis menyebabkan ketertarikan untuk produksi biosurfaktan dalam skala besar semakin meningkat. Salah satu cara untuk meningkatkan produksi biosurfaktan adalah dengan melakukan optimasi sumber nitrogen pada medium produksi. Oleh karena itu penelitian ini bertujuan untuk mengetahui sumber nitrogen terbaik yang dapat digunakan untuk produksi biosurfaktan secara optimal. Penelitian ini menggunakan lima jenis sumber nitrogen antara lain urea, NH4Cl, NaNO3, (NH4)2SO4, dan KNO3 sedangkan jenis bakteri halofil yang digunakan adalah Halomonas elongata BK-AG18. Hasil penelitian ini menunjukkan bahwa urea merupakan sumber nitrogen terbaik yang digunakan untuk medium produksi biosurfaktan. Hal ini ditunjukkan dari hasil yang diperoleh dari diameter penyebaran minyak sebesar 3 cm.

Implementation of Biocatalysis in Continuous Flow for the Synthesis of Small Cyclic Amines

Significant progress has been made in establishing transaminases as robust biocatalysts for the green and scalable synthesis of a diverse range of chiral amines. However, very few examples on the amination of small cyclic ketones have been reported. Cyclic ketones are particularly challenging for transaminase enzymes because they do not display the well-defined small and large substituent areas that are characteristic for the bio- catalytic mechanism. In this work, we exploited the broad substrate scope of the (S)-selective transaminase from Halomonas elongata (HeWT) to develop an efficient biocatalytic system in continuous flow to generate a range of small cyclic amines which feature very often in pharmaceuticals and agrochemicals. [3] Tetrahydrofuran-3-one and other challenging prochiral ketones were rapidly (5–45 min) transformed to their corresponding amines with excellent molar conversion (94–99%) and moderate to excellent ee.