Microencapsulation and Fermentation of Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12

Because of poor survival of probiotic bacteria, microencapsulation evolved from the immobilized cell culture technology used in the biotechnological industry. Two probiotic strains, Bifidobacterium (BB-12) and Lactobacillus acidophilus (LA-5) were immobilized in calcium alginate by extrusion method. Encapsulation parameters and efficacy of this method were evaluated. Growth factors of these two bacteria were also measured by culturing in 10-L fermenter. Growth curves were obtained with respect to optical density and dry biomass weight. Encapsulation yield was over than 60% in each experiment. Scanning electron microscopy (SEM) of Entrapment of cells in alginate matrix and cross-sections of dried bead were obtained and illustrated. Bifidobacterium have been shown better biotechnological properties

Isolation and Identification of Crude Oil Degrading and Biosurfactant Producing Bacteria from the Oil-Contaminated Soils of Gachsaran

Background and Objectives: Petroleum hydrocarbons are harmful to the environment, human health, and all other living creatures. Oil and its byproducts in contact with water block sunshine to phytoplanktons and thus break the food chain and damage the marine food source. This study aims to isolate the crude oil degrading and biosurfactant producing bacteria from the oil contaminated soils of Gachsaran, Iran. Materials and Methods: Isolation was performed in peptone-water medium with yeast extract. Oil displacement area, emulsification index and bacterial phylogeny using 16S rRNA analysis were studied. Results and Conclusion: Three isolates were able to degrade the crude oil. In the first day, there were two phases in the medium; after a few days, these three bacteria degraded the crude oil until there was only one phase left in the medium. One strain was selected as a superior strain by homogenizing until the medium became clear and transparent. This method confirmed that the strain produces biosurfactant. According to the morphological and biochemical tests, the strain isolated from the oil contaminated soils is a member of Bacillus subtilis, so to study the bacterial phylogeny and taxonomy of the strain, an analysis of 16S rRNA was carried out, and the phylogenic tree confirmed them. The results verified that oil contaminated soils are good source for isolation of the biosurfactant producing bacteria

L-tryptophan production by Escherichia coli in the presence of Iranian cane molasses

The essential amino acid L-tryptophan (Trp) has importance as a pharmaceutical agent, especially in neuro-medicine. It is also added to feed products as a food fortifier. Furthermore, application of Trp is widespread in biotechnology. Trp is produced by a condensation reaction between indole and L-serine, which is catalyzed by bacterial tryptophanase activity. In this study, we have investigated Trp production using microbial system in the presence and absence of its precursors and Iranian cane molasses. The results showed that the optimum concentration of the molasses for maximum bacterial growth is 10 g/lit. Furthermore, in order to assay the amount of tryptophan produced, thin layer chromatography was used. The results showed that Iranian cane molasses contains considerable amounts of serine and indole, enough for Trp production (0.48 mM) in culture medium. But additional indole has inhibitory effects on Trp production. The data are compatible with previous reports on inhibitory effect of indole not only on cell growth but also on tryptophanase formation and function

Optimization of Protease Production by Psychrotrophic Rheinheimera sp. with Response Surface Methodology

Background and Objectives: Psychrotrophic bacteria can produce enzymes at low temperatures; this provides a wide biotechnological potential, and offers numerous economical advantages over the use of mesophilic bacteria. In this study, extracellular protease production by psychrotrophic Rheinheimera sp. (KM459533) was optimized by the response surface methodology.Materials and Methods: The culture medium was tryptic soy broth containing 1% (w v -1 ) skim milk. First, the effects of variables were independently evaluated on the microbial growth and protease production by one-factor-at-a-time method within the following ranges: incubation time 24-120 h, temperature 15-37°C, pH 6- 11, skim milk concentration 0-2% (w v -1 ), and inoculum size 0.5-3% (v v -1 ). The combinational effects of the four major variable including temperature, pH, skim milk concentration, and inoculum size were then evaluated within 96 h using response surface methodology through 27 experiments.Results and Conclusion: In one-factor-at-a-time method, high cell density was detected at 72h, 20°C, pH 7, skim milk 2% (w v -1 ), and inoculum size 3% (v v -1 ), and maximum enzyme production (533.74 Uml-1 ) was achieved at 96h, 20°C, pH 9, skim milk 1% (w v -1 ), and inoculum size 3% (v v -1 ). The response surface methodology study showed that pH is the most effective factor in enzyme production, and among the other variables, only temperature had significant interaction with pH and inoculum size. The determination coefficient (R2 =0.9544) and non-significant lack of fit demonstrated correlation between the experimental and predicted values. The optimal conditions predicted by the response surface methodology for protease production were defined as: 22C, pH 8.5, skim milk 1.1% (w v -1 ), and inoculum size 4% (v v -1 ). Protease production under these conditions reached to 567.19 Uml-1 . The use of response surface methodology in this study increased protease production by eight times as compared to the observed before optimization.Conflict of interests: The authors declare no conflict of interest

Growth optimization and identification of an ω-transaminase by a novel native PAGE activity staining method in a Bacillus sp. strain BaH isolated from Iranian soil

ω-Transaminases’ (ω-TAs) importance for synthesizing chiral amines led to the development of different methods to quickly identify and characterize new sources of these enzymes. Here we describe the optimization of growth and induction of such an enzyme in a wild type strain of Bacillus sp. strain BaH (IBRC-M 11337) isolated from Iranian soil in shaking flasks by the response surface methodology (RSM). Optimum conditions were set in a multiplexed bench-top bioreactor system (Sixfors). ω-TA activity of obtained biomass was checked by an innovative efficient colorimetric assay for localizing ω-TAs in crude extracts on acrylamide gel by using ortho-xylylenediamine (OXD) as amino donor. The application of the established OXD assay is thereby expanded from high-throughput activity screenings and colony-based screenings of heterologously expressed mutants to a direct identification of ω-TAs in wild-type strains: This assay can be used to detect the protein band of the respective enzyme in crude extracts of novel isolates by visual inspection of native PAGEs without any upstream protein purification, thus enabling subsequent further investigations of a newly discovered enzyme directly from the crude extract

Investigation of a robust pretreatment technique based on ultrasound-assisted, cost-effective ionic liquid for enhancing saccharification and bioethanol production from wheat straw

Abstract Application of cost-effective pretreatment of wheat straw is an important stage for massive bioethanol production. A new approach is aimed to enhance the pretreatment of wheat straw by using low-cost ionic liquid [TEA][HSO4] coupled with ultrasound irradiation. The pretreatment was conducted both at room temperature and at 130 °C with a high biomass loading rate of 20% and 20% wt water assisted by ultrasound at 100 W-24 kHz for 15 and 30 min. Wheat straw pretreated at 130 °C for 15 and 30 min had high delignification rates of 67.8% and 74.9%, respectively, and hemicellulose removal rates of 47.0% and 52.2%. Moreover, this pretreatment resulted in producing total reducing sugars of 24.5 and 32.1 mg/mL in enzymatic saccharification, respectively, which corresponds to saccharification yields of 67.7% and 79.8% with commercial cellulase enzyme CelluMax for 72 h. The ethanol generation rates of 38.9 and 42.0 g/L were attained for pretreated samples for 15 and 30 min, equivalent to the yields of 76.1% and 82.2% of the maximum theoretical yield following 48 h of fermentation. This demonstration provided a cheap and promising pretreatment technology in terms of efficiency and shortening the pretreatment time based on applying low-cost ionic liquid and efficient ultrasound pretreatment techniques, which facilitated the feasibility of this approach and could further develop the future of biorefinery

Investigation of crude oil-degrading and biosurfactant-producing Bacillus subtiliswild-type strains from Iran crude oil-contaminated soil and wastewater

This poster was presented at the second International Biosurfactant Conference in September 2022, at the University of Hohenheim, Stuttgart, Germany. The Bioprocess Engineering department was the host of this conference, and I worked there as a PhD visiting student. </p