ISSN 2285-1364, ISSN CD-ROM 2285-5521, ISSN ONLINE 2285-1372, ISSN-L 2285-1364
 

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Elisabeta Elena TĂNASE, Maria RÂPĂ, Ovidiu POPA

It is well known that plastic waste has become a great problem for the environment all over the world. Conventional polymeric materials are not easily degraded because they are resistant against microbial attack; they accumulate in the environment and represent a significant source of environmental pollution. These problems caused by synthetic waste have led to the need for developing new polymeric materials that can be biodegradable and biocompatible with the environment, to replace the conventional ones. Over the past years a lot of attention has been paid to biodegradable polymers based on renewable resources because of their wide range of applications in packaging, agriculture or biomedical fields. This paper aims to present a review regarding the development of biopolymers and biocomposites based on renewable resources, their properties and the area of their application.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Gabriela LUTA, Daniela BALAN, Evelina GHERGHINA, Vasilica SIMION, Florentina MATEI, Stefana JURCOANE

Proteases are very important industrial enzymes, accounting for more than a half of the total enzymes used in the world. For leather industry they have an important technological role as well as for waste degradation.This paper reports the researches done for obtaining immobilized proteolytic complexes for using in biodegradation purposes. Three bacterial strains were cultivated in minimal medium with 0.6% sheep fur as carbon source. The concentration of the culture medium was performed by rotaevaporator, at 35 C, followed by lyophilisation at 0.04 mbar, for 18 hours. The concentrated complex was immobilized on clay and adabline, which are inert and cheap supports that are technically convenient because we used the adsorption process for immobilization. Collagenase and keratinase activity was assayed for estimation of the immobilization efficiency. The best results were obtained when the immobilization support was clay, using a 2:1(ml enzyme/g immobilization support) ratio.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Laura-Dorina DINU, Camelia DIGUTA, Matilda CIUCA, Larisa URSU, Calina Petruta CORNEA

Leaf rust of wheat (Triticum aestivum L.) is caused by Puccinia triticina Ericks and is a common disease of this plant species in northwest, southern, southeast, and eastern Europe. It has been shown that the severity of leaf rust increased in the last years in many regions of Europe and highlighted the need for selection of wheat cultivars with race specific resistance genes. In order to select wheat resistant lines and develop efficient management programs for disease control, the characterization (phenotypic and molecular) of leaf rust races isolated from specific area is an important step of researches. To date, several molecular markers have been used to describe variation in P. triticina in Europe and worldwide. The aim of this work was to study the molecular diversity of P.triticina collected from Romanian fields (Fundulea, Livada, Pitesti). Single-uredinial isolates were obtained from several populations of P.triticina and used for inoculation of detached wheat leaves cultivar F133. Genomic DNA was isolated from 20 fresh single-uredinial samples (2-10 mg spores) and from eight populations of P. triticina urediniospores (10-20 mg spores) using OmniPrep for Fungus kit. The molecular polymorphism was evaluated through RAPD (with eight decameric primers) and by using 15 SSR primers and two ISSR primers. Results showed a reduced polymorphism at population level, but not identity, as indicated the RAPD analysis. No more than two alleles were detected in the leaf rust populations with the SSR markers used in experiments according to our separation protocol. Differences in the SSR loci were detected in the single-uredinial isolates. Similar results were obtained with ISSR primers: ISSR 17898A primer allowed the detection of the highest polymorphism among the individual isolates. Evidence for molecular variability between single urediniospores isolates will be correlated with the virulence phenotypic analysis in further studies.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Panteley DENEV, Nadezhda PETKOVA, Ivan IVANOV, Biser SIRAKOV, Radka VRANCHEVA, Atanas PAVLOV

The object of our current study is to determinate the biologically active substance presented in the taproots of Bulgarian medicinal plant common chicory (Cichorium intybus L.). The carbohydrate composition, the amount of total phenols, the total flavanoides content and the antioxidant activity in the obtained sequential ethanol and water extracts has been evaluated. The amount of inulin-type fructans was defined by the resorcinol assay. The sugars, fructooligosacharides and inulin contents of the obtained extracts were analyzed by TLC and HPLC-RID methods. The total phenolic and flavonoid quantities were analysed by using Folin–Ciocalteu’s and Al(NO3)3 reagents, respectively. The antioxidant activity was defined by four method (DPPH, ABTS, FRAP and CUPRAC). The total fructan content in taproots is in range 23 % dw. The presence of monosaccharide glucose, fructose, sucrose and trisaccharides 1-kestose, nystose in the ethanol extracts was observed in the ethanol extracts. The analysis of water extracts revealed the high level of inulin (14 %), total phenols and flavonoids (7 mg/g GAE dw and 2 mg QE/g dw, respectively). The 95 % (v/v) ethanol extracts of roots collected during autumn showed the most well-pronounced antioxidant activity as followed: DPPH - 31 mM TE/g dw, ABTS - 49 mM TE/g dw, FRAP - 28 mM TE/g dw and CUPRAC - 127 mM TE/g dw.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Marian PETRE, Violeta PETRE, Ionela RUSEA

Year by year, large amounts of fruit tree wastes, such as etiolated leaves, woody wastes (old branches, dried trunks, unproductive shoots) resulting from annual pruning or cleaning of fruit trees are produced in many orchards becoming in the end huge sources of pollution. The main objective of this research work was focused on the development, implementation and testing of experimental model for ecological recycling of fruit tree wastes through controlled cultivation of the eatable mushroom species Lentinus edodes, Pleurotus ostreatus and P. eryngii on substrates made of leaves, branches and trunks of apple, plum and apricot trees. All three mushroom species were used as pure culture to be grown on different variants of substrates made of fruit tree wastes, namely etiolated dried leaves, shoots and trunks as well as distilled marc of fruits after their use as raw matter for alcohol fermentation and distillation. All substrates were steam sterilized at 123 °C, 50 min, and after that they were inoculated with the pure mushroom cultures. After 30- 50 days of incubation at 23 °C, depending on the mushroom species, the first buttons emerged and after one or two days they developed the mature fruit bodies. After a period of 120 days mushroom growing on the substrates made of fruit tree wastes the results showed a fast development of Pleurotus species, respectively P. ostreatus was faster than P. eryngii, and had registered a better productivity than L. edodes. The implementation of such an experimental model of green technology will determine the full recovery of all fruit tree wastes produced in orchards (leaves, branches, wood stems) and their fast recycling through the natural food chains of the whole organic matter. Inside the newly formed food chains, the fruit tree wastes were the basic link on which the eatable mushroom species, such as L. edodes, P. ostreatus and P. eryngii that decompose lignin, hemicellulose and cellulose have synthesized natural organic compounds through the carpophores that were finally used as food products by the human consumers.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Iuliana RAUT, Mariana CALIN, Gelu VASILESCU, Mihaela BADEA DONI, Tatiana SESAN, Luiza JECU

Biological control represents an important approach of agricultural biotechnology for controlling many fungal plant pathogens. Trichoderma spp. are the most promising and effective bioagents against many plant pathogenic fungi. In present paper, two strains of Trichoderma aspellerum isolated from soil were screened for their efficacy against some common soil borne plant pathogens by dual culture technique. Trichoderma strains were grown in potato dextrose broth and collected metabolites were amended to PDA medium to obtain 5, 10, 25 and 50% concentration in Petri plates. The solidified agar plates were inoculated with pathogen and incubated at 25 ± 2ºC for 7 days. The colony diameter was measured and percentage inhibition of radial growth was calculated. Both antagonists’ strains produced non-volatile metabolites and inhibit the mycelial growth of Fusarium graminearum, Rhizoctonia solani and Pythium umtimum.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Iulian GROSU, Florentina ISRAEL-ROMING, Oana-Alina SICUIA, Florica CONSTANTINESCU, Gabriela POPA, Călina Petruța CORNEA

The impact of mycotoxin contamination of foodstuffs and feedstuffs on human and animal health is well documented. Trichothecene mycotoxins are metabolic compounds produced by various Fusarium species such as F.graminearum, F. culmorum, F. sporotrichioides, F. poae and F. equiseti on different grains like wheat, oats or maize. The most significant thrichothecenes produced by fusaria are T-2 toxin, HT-2 toxin, diacetoxyscirpenol (type A) and nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol (type B). Deoxynivalenol (DON), mainly synthesized by F. graminearum and F. culmorum (that produce Fusarium Head Blight disease = FHB), is the most common trichothecene contaminant of wheat, and appears to play an important role in the aggressiveness of both species toward wheat. In order to prevent the contamination of the cereals with mycotoxigenic fungi, various strategies were developed (cultural practices: tillage, crop rotation; use of fungicides, resistant cultivars or biological control agents = BCAs). Because of the low efficacy of fungicides to control members of the Fusarium head blight Complex, the selection of highly efficient antagonists is of great interest for the specialists all over the world. Environmental friendly, the use of BCA is an important additional strategy that can be used as part of an integrated management of FHB. For this reason, the aim of our work was to select potential microbial antagonists that are able to inhibit the growth of Fusarium graminearum and F.culmorum, and to prevent the presence of DON on wheat. 37 Fusarium spp. strains were used in experiments and the in vitro aggressiveness of these isolates was determined. Twelve fungal strains with differences in the aggressiveness potential and DON biosynthesis were selected and used for interactions with eight bacterial strains isolated from compost or soil. Four out of the eight bacterial strains used were selected based on their high inhibitory activity against all the fungal isolates. Specific microscopically modifications of hyphae were observed at the edge of fungal colonies near the antagonist. The effect of the bacterial antagonists on DON accumulation in specific culture medium was also checked by TLC method. The results showed the possibility to use one or more bacterial strains as a tool for the biological control of FHB agents that survives in crop residues.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by ESTABLISHMENT OF TESTS FOR FACILITATING SCREENING OF DROUGHT TOLERANCE IN SOYBEAN

Abiotic stress due to environmental changes causing water deficit, extreme temperatures and low atmospheric humidity decreases plant productivity. One of the elements of overcoming the stress is to develop new varieties. However, drought tolerance has a complex nature which makes this problem difficult to solve and involves different approaches and methods. The process of creating new varieties could be facilitated by screening of genotypes with higher resistance. In this respect laboratory tests in in vitro and ex vitro conditions could complement in vivo experiments. To make stress models availability of a factor causing or imitating the stress is required. In addition, choosing appropriate criteria of correspondence between responses in field and in laboratory conditions is crucial. The high molecular weight substance polyethylene glycol (PEG) causes osmotic shock which is one of the components of the drought. Different concentrations (2-10 %) of PEG were used in our experiments. PEG was added into the media for germination of seeds and its effect on water absorption and seed development was followed. Soybean lines obtained previously and varieties (used as standard) were studied. Positive correlation between the level of drought tolerance of the genotypes in the field and in laboratory experiments was identified. The results are interesting for establishment of quick screening tests for identification of lines appropriate for breeding programs of soybean, commonly used grain legume with multiple product application.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Silvia-Simona GROSU-TUDOR, Medana ZAMFIR

Lactic acid bacteria (LAB) play a key role in the food fermentation process since they contribute to the texture, flavor,quality and conservation of the fermented products. Several LAB strains have been shown to produceexopolysaccharides (EPS), with potential applications in food industry, since they can act as natural thickeners thatimprove the texture of the final product, decrease syneresis and reduce the fat levels in fermented foods. In situproduction of EPS by LAB to get a desired texture and mouthfeel of some fermented products is being explored, inorder to replace polysaccharides from plants or animals, currently in use. Moreover, it has been suggested that someEPS produced by LAB have prebiotic activity, contributing to the promotion of human gastrointestinal health. Duringthis study, five new EPS-producing LAB strains have been selected from 21 strains isolated from fermented vegetables.The mucoidness/ropiness of the colonies developed on MRS agar media containing different carbon sources (glucose,sucrose, fructose, galactose, lactose, or xylose) was firstly observed. EPS presence in the culture supernatant wasdetected through gel permeation chromatography (GPC). The EPS material was isolated from these strains by acetoneprecipitation, then dialysed, dried and weighted. The molecular mass was estimated by the same GPC method, while themonomer composition was determined by automated thin layer chromatography (TLC), after hydrolysis with 8N HCl.One of the positive strain, Leuconostoc mesenteroides/pseudomesenteroides 406 has been shown to produce largeamounts of EPS, of about 15 g/L and two strains, Leuconostoc citreum/lactis/garlicum 167 and Leuconostoc sp. 208were able to produce around 6 g/L of EPS. All isolated EPS have a high molecular mass, of above 1400 KDa, and amonomer composition dominated by the presence of glucose. The influence of the growth medium composition andincubation temperature on the EPS biosynthesis was also investigated. Three LAB strains, that were shown to producehigh amounts of EPS, have been selected to be used in this study. It was shown that some mild stress conditions mightstimulate, in some cases, the EPS-production.

[Read full article] [Citation]

Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XVIII
Written by Mădălin ENACHE, Simona NEAGU, Roxana COJOC

This work aims to reveal the ability of halophilic microorganisms, both bacteria and archaea, isolated from salted lakes and salt crystals from the salt mine, to produce a wide range of extracellular hydrolytic enzymes able to degrade several macromolecular substrates, such as sugar based polymers or proteins. A relatively wide positive spectrum of extracellular hydrolases for tested substrates was recorded from archaeal and bacterial strains isolated from investigated salted area. The number appears to be higher if comparing isolates from salt lakes with isolates from salt crystal. In the case of tested halophilic bacteria were found enzymes capable of hydrolyzing starch, casein, Tween80 and carboxymethylcellulose. In the case of microorganisms belonging to the Archaea domain, identified on the surface of the crystal and belonging to Halorubrum genus was detected the ability to degrade starch and seldom Tween80. In some cases, a combined hydrolytic activity has been observed. One halophilic bacterial strain combined cellulase and esterase activities and other strains combined two or more hydrolytic activities. The enzymes degrading starch appear to have a wide distribution and when compared the 16S rRNA phylogeny distribution of investigated strains with the absence or presence of amylase activity, the data showed a very high correlation degree.

[Read full article] [Citation]

Page 2 of 5

The publisher is not responsible for the opinions published in the Volume. They represent the authors’ point of view.

© 2019 Scientific Bulletin Series F.“Biotechnologies“. All Rights Reserved. To be cited: Scientific Bulletin Series F.“Biotechnologies“.

Powered by INTELIDEV

Biotechnologies Journal