Statistical Optimization Approaches for High Cell Biomass Production of Lactobacillus casei

216-221Probiotic bacteria are known to treat and prevent diseases and hence promote physical and mental wellness due to their significant brain-gut relationship. The main challenge involved in probiotic commercialization is the bio processing limitation to produce high cell mass, especially with the cultivation of lactic acid bacteria which produces lactic acid as a by product. Synthesis of lactic acid by lactic acid bacteria inhibits bacterial growth, and in turn disrupts high cell mass production. Current work presents the findings for Lactobacillus casei medium optimization by response surface methodology in shake flask level. A simple medium using 4 components: lactose, soybean meal, yeast extract and magnesium sulphate has been identified to produce high cell mass than generic mediaused for probiotic cultivation, such as the MRS medium. Secondly, response surface methodology using Box-Behken Design was employed as an optimization strategy. After optimization process, the production of Lactobacillus casei biomass increased by about 164.6% recording 6.51g.L-1 compared to cell biomass obtained using initial un-optimized medium (2.46g.L-1)

The effect of mycorrhizal fungi and organic fertilizers on quantitative and qualitative traits of two important satureja species

The quantitative yield and essential oil percentage and composition of two important savory species in response to various fertilizers were explored in a field experiment as a factorial study based on a randomized complete block design with three replications in north Lorestan, Iran, in 2017–2019. The first factor was assigned to three mycorrhizal fungi (Funneliformis mosseae, Rhizophagus irregularis, and Glomus fasciculatum), phosphate biofertilizer (Baravar-2), fish manure (800 kg/ha), cattle manure (20 t/ha), vermicompost (5 t/ha), and a control (no fertilization); the second factor was assigned to two savory species, including Satureja khuzestanica and S. rechingeri. The results of the combined analysis of variance for the second and third years showed that the simple effects of fertilizers and species were significant on all recorded traits, except for some constituents of the essential oil. Among the mycorrhizal fungi, R. irregularis and S. khuzestanica outperformed S. rechingeri in all traits, except for essential oil content and yield. The interaction between year and species was significant for all traits. The essential oil content of S. rechingeri in the third year (5.1%) was 18% higher than that of S. rechingeri in the second year (4.3%) and 41% higher than that of S. khuzestanica in the third year (3.6%). According to the results, the foliar application of vermin compost at a rate of 5 t/ha can contribute to the sustainable production of both savory species, improving their growth and essential oil yield

Modelling pressure deficient water distribution networks in EPANET

Nodal outflows in a pressure deficient water distribution network depend on available nodal heads. Thus, node-head flow relationship exists at each node which are solved along with other appropriate equations for simulation. While using EPANET for such simulation, source code needs to be modified to obtain direct solution. The other way is to use EPANET iteratively wherein node head-flow relationships are satisfied externally. Herein, a simple non-iterative method is suggested in which artificial string of Check Valve, Flow Control Valve, and Emitter are added in series at each demand node to model pressure deficient water distribution network

Tree bark scrape fungus: a potential source of laccase for application in bioremediation of non-textile dyes

Although laccase has been recognized as a wonder molecule and green enzyme, the use of low yielding fungal strains, poor production, purification, and low enzyme kinetics have hampered its large-scale application. Thus,this study aims to select high yielding fungal strains and optimize the production, purification, and kinetics of laccase of Aspergillus sp. HB-RZ4. The results obtained indicated that Aspergillus sp. HB-RZ4 produced a significantly large amount of laccase under meso-acidophilic shaking conditions in a medium containing glucose and yeast extract. A 25 μM CuSO4 was observed to enhance the enzyme yield. The enzyme was best purified on a Sephadex G-100 column. The purified enzyme resembled laccase of A. flavus. The kinetics of the purified enzyme revealed high substrate specificity and good velocity of reaction,using ABTS as a substrate. The enzyme was observed to be stable over various pH values and temperatures. The peptide structure of the purified enzyme was found to resemble laccase of A. kawachii IFO 4308. The fungus was observed to decolorize various dyes independent of the requirement of a laccase mediator system. Aspergillus sp. HB-RZ4 was observed to be a potent natural producer of laccase, and it decolorized the dyes even in the absence of a laccase mediator system. Thus, it can be used for bioremediation of effluent that contains non-textile dyes. © 2020 Sayyed et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Statistically Designed Bioprocess for Enhanced Production of Alkaline Protease in Bacillus cereus HP_RZ17

491-498Alkaline protease is one of the bulk enzymes having wide commercial demand for various applications. It is commercially produced by a submerged fermentation process employing various bacteria, Bacillus sp. being the most widely used species. Statistical optimization of the process for the production of alkaline proteases from rhizospheric bacteria and its application in the biocontrol of plant pathogens has not been explored fully and needs to be studied for the development of efficient bioprocess. We report the enhanced production of alkaline protease in the minimal salt medium (MSM) optimized using statistical approaches such as Plackett Burman Design (PBD) and Response Surface Methodology (RSM). In the first step; PBD, among the total eight variables, three variables namely, yeast extract (pppBacillus cereus HP_RZ17. These three variables were further analyzed in the second step i.e. Central Composite Design (CCD) of RSM. The optimum yield of alkaline protease by B. cereus HP_RZ17 (130.72 UmL-1) was obtained under the optimal conditions such as yeast extract (0.899% w/v), fructose (0.873% w/v), and pH (11.25) of production media. The statistically optimized values of variables used for the scale-up of the process at 5 L capacity bioreactor enhanced the alkaline protease yield (132.48 UmL-1) by 1.09 fold vis-à-vis un-optimized protocol (121.96 UmL-1) in B. cereus HP_RZ17

UV Induced Mutagenesis Elevates the Production of Laccase in Enterobacter cloacae

442-448The increasing commercial significance of microbial laccase in various fields compels the supply of enzymes in large quantities at an affordable price. Laccase has been produced by a wide variety of wild cultures of bacteria and fungi, the high yielding strains are always desired to meet the increasing demand of laccase. Although various approaches have been proposed for improving the yield of laccase, UV mutagenesis is known as the best method of improving the strains for better yield of microbial metabolites. However, the reports on the use of UV light in strain improvement for laccase production by the use of Enterobacter sp. are scarce and need to be explored fully. For this purpose present study was aimed to improve the laccase production in Enterobacter cloacae through UV mutagenesis. We report enhanced production of laccase in a high yielding strain of E. cloacae isolated from the soap industry waste. UV mutagenesis of a wild strain of E. cloacae resulted in 3.09 folds further improvement in the production. Optimum laccase synthesis was reported at 26 h, of incubation at 30ºC under neutral pH (7.0) conditions. This high yielding mutant strain will have great industrial significance for laccase production

Statistical Optimization Approaches for High Cell Biomass Production of Lactobacillus casei

Probiotic bacteria are known to treat and prevent diseases and hence promote physical and mental wellness due to their significant brain-gut relationship. The main challenge involved in probiotic commercialization is the bio processing limitation to produce high cell mass, especially with the cultivation of lactic acid bacteria which produces lactic acid as a by product. Synthesis of lactic acid by lactic acid bacteria inhibits bacterial growth, and in turn disrupts high cell mass production. Current work presents the findings for Lactobacillus casei medium optimization by response surface methodology in shake flask level. A simple medium using 4 components: lactose, soybean meal, yeast extract and magnesium sulphate has been identified to produce high cell mass than generic mediaused for probiotic cultivation, such as the MRS medium. Secondly, response surface methodology using Box-Behken Design was employed as an optimization strategy. After optimization process, the production of Lactobacillus casei biomass increased by about 164.6% recording 6.51g.L-1 compared to cell biomass obtained using initial un-optimized medium (2.46g.L-1)

Statistical based bioprocess design for improved production of amylase from halophilic bacillus sp. H7 isolated from marine water

Amylase (EC 3.2.1.1) enzyme has gained tremendous demand in various industries, including wastewater treatment, bioremediation and nano-biotechnology. This compels the availability of enzyme in greater yields that can be achieved by employing potential amylase-producing cultures and statistical optimization. The use of Plackett–Burman design (PBD) that evaluates various medium components and having two-level factorial designs help to determine the factor and its level to increase the yield of product. In the present work, we are reporting the screening of amylase-producing marine bacterial strain identified as Bacillus sp. H7 by 16S rRNA. The use of two-stage statistical optimization, i.e., PBD and response surface methodology (RSM), using central composite design (CCD) further improved the production of amylase. A 1.31-fold increase in amylase production was evident using a 5.0 L laboratory-scale bioreactor. Statistical optimization gives the exact idea of variables that influence the production of enzymes, and hence, the statistical approach offers the best way to optimize the bioprocess. The high catalytic efficiency (kcat/Km) of amylase from Bacillus sp. H7 on soluble starch was estimated to be 13.73 mL/s/mg

A population biological model with a singular nonlinearity

summary:We consider the existence of positive solutions of the singular nonlinear semipositone problem of the form $$\begin {cases} -{\rm div}(|x|^{-\alpha p}|\nabla u|^{p-2}\nabla u)=|x|^{-(\alpha +1)p+\beta } \Big (a u^{p-1}-f(u)-\dfrac {c}{u^{\gamma }}\Big ), \quad x\in \Omega ,\\ u=0, \quad x\in \partial \Omega , \end {cases}$$ where $\Omega$ is a bounded smooth domain of ${\mathbb R}^N$ with $0\in \Omega$, $1<p<N$, $0\leq \alpha < {(N-p)}/{p}$, $\gamma \in (0,1)$, and $a$, $\beta$, $c$ and $\lambda$ are positive parameters. Here $f\colon [0,\infty )\to {\mathbb R}$ is a continuous function. This model arises in the studies of population biology of one species with $u$ representing the concentration of the species. We discuss the existence of a positive solution when $f$ satisfies certain additional conditions. We use the method of sub-supersolutions to establish our results