Acta Microbiologica Bulgarica

57-68

Authors: Gocheva Y., Angelova M., Krumova E.

The scope of this review is the literature published over the last 10 years and presents information on studies conducted on microscopic fungi isolated from various natural saline ecosystems (aquatic and terrestrial). Another interesting point is that it presents a classification of halophilic fungi and the concepts of halotolerant and halophilic microorganisms. The main aim of this review is to show fungal diversity of different natural salinity ecosystems and the biotechnological potential of halophilic and halotolerant fun¬gi as producers of biologically active substances (antibiotics, enzymes, polysaccharides). A careful study on halophilic and halotolerant fungi could offer new biologically active compounds that could be used in many industrial processes taking place in unfavorable conditions, such as high salt concentration, low water activity, high pressure or high temperature, etc.

81-87

Authors: Nacheva L., Christova N., Stoineva I., Petrov P., Kabaivanova L.

Aliphatic and aromatic xenobiotics can cause serious ecological problems due to their widespread oc¬currence and toxicity. The investigated strain Micrococcus luteus BN56 appeared to be capable of degrad¬ing both aromatic and aliphatic xenobiotics simultaneously as carbon and energy sources. Adaptation of the investigated strain was carried out with repeated additions of xenobiotic to the medium. The cells showed the highest capacity for biodegradation after 10 passages simultaneously degrading both xenobiotics - 10 g/l (100%) phenol and 10 g/l (100%) n-hexadecane, in 20 active cycles of operation (duration of 12 - 36 h). The simultaneous biodegradation was not hindered by either of them. By applying an in situ immobilization procedure using poly(acrylamide) (PAAam) and poly(ethylene oxide) (PEO) cryogel matrices, these pro¬cesses were intensified, stabilized and reached 40 cycles of repeated operation of successful simultaneous biodegradation of the aromatic and the aliphatic xenobiotics (20g/l + 20g/l). This capability can be further implemented in different real-world bioremediation processes.

95-97

Authors: Petrov N., Stoyanova M., Stoev A., Gaur R. K.

Outbreaks of potato virus Y (PVY) have a serious negative impact on agricultural production, leading to significant losses. The need for an effective PVY control technique is essential to reduce yield losses in agriculture. Plants use a defense mechanism called RNA silencing, which was used to control PVY. Post-transcriptional gene silencing (PTGS) of major viral genes was induced by specific siRNAs that trig¬ger specific degradation of viral RNA by forming a multi-component RNA-induced silencing complex (RISC). By using PTGS, resistance of potato varieties to PVY was achieved.

3-9

Authors: Galabov, A.S.

We described the pyrimidine derivative dipyridamole (DP) as an interferon (IFN) inducer in culti¬vated in vitro lymphoid cells, administrated orally in mice and in humans attaining high IFN titres within 24 hours. Gut-associated lymphoid tissue was identified as the inducer target. IFN-antagonistic period was established. Three double-blind placebo trials (more than 6000 participants proved that DP acts as a prophy¬lactic for influenza and viral acute respiratory diseases. Experimental evidence proved that the IFN-induc¬ing activity of DP is due to its capacity to inhibit cAMP phosphodiesterase. Additionally, DP demonstrates a marked inhibitory effect on the replication of a broad spectrum of viruses. It was established that DP-in¬duced IFN production in humans is strongly dependent of compound pharmacokinetics. DP activities were followed and described in lupus erythematosus, chronic pulmonary diseases, liver diseases, in ophthalmology, dermatology (herpesvirus and papillomavirus infections) and AIDS. Special attention was given to a possible DP’s effect in COVID-19 patients.

22-26

Authors: Beev, G., Michaylova, M., Dinev, T., Naydenova, N., Tzanova, M., Urshev, Z.

Lactic acid bacteria are widespread in nature and occur naturally as indigenous microflora in raw milk. Considering that buffalo milk is an excellent medium for the growth of a large variety of lactic acid bacteria, the aim of this study was the isolation of Lactobacillus spp. strains from raw buffalo milk orig¬inating from different areas and their species identification, using Amplified Ribosomal DNA Restriction Analysis (ARDRA) and a set of five reference strains of the most frequently isolated Lactobacillus species. From the analysis of the patterns generated after treatment with HaeIII it was found that 24 (88.8%) of the isolates had profiles that matched the reference 16S rDNA of Lactobacillus casei. The restriction profiles of the remaining three isolates (12.2%) did not match any of the reference strains and they were identified by API 50 CHL as Lactobacillus fermentum. This indicates that L. casei is highly adaptive and dominates in raw buffalo milk regardless of the climatic conditions and the method of raising animals.

34-45

Authors: Adebayo-Tayo, B.C., Briggs-Kamara, A.I., Salaam, A.M.

The study aimed to investigate the phytochemical, antioxidant, antimicrobial potential and GC-MS analysis of crude and different fractions of Nigella sativa seed extract. Crude methanol extract of N. sativa seed was obtained, the phytochemical components, antioxidant and antimicrobial potential of the seed were evaluated and the crude extract was partitioned using different solvents. Antimicrobial activity was determined and GC-MS analysis of the fractions was conducted. Saponins, flavonoids, alkanoids (19.8%, 41.6% and 82%), tannins, anthraquinones, terpenoids and steroids were present while cardiac glycosides were not detected. The hexane and chloroform fraction yielded 60.17% and 0.42% from the partitioned crude ex¬tract, respectively. DPPH (2, 2-dipheniyl-1-picrylhydrazyl), total phenolic content and ferric reducing antioxidant power (40.37, 20.1 and 48.4 %) increased in a dose-dependent manner. N. sativa fractions had varied antibacterial activity against the test bacteria and fungi. Staphylococcus aureus ATCC29213 and methicillin-resistant S. epidermidis3 were highly susceptible (60.0 mm and 56.0 mm) to chloroform fractions while Trichophyton sp. and Candida tropicalis had the highest susceptibility (50 mm) to the hexane fraction. A total of 24 dis¬tinct phyto-components were identified, and 9, 8, 7, 3 and 4 compounds were found in the hexane, meth¬anol, ethyl acetate, chloroform fractions and the crude extract. The compounds were 2-Chloroethyl vinyl sulfide, 11-Octadecenoic acid, methyl ester, Cyclononene, 3,8-Dioxatricyclo[5.1.0.0(2,4)] octane, 4-ethe¬nyl-, 7-Hydroxy-3-(1,1-dimethylprop-2-enyl)coumarin, Trimethylsilyl-di(timethylsiloxy)-silane among others. The crude, hexane and chloroform (%) fractions contained 99.3%, 96.42% and 97.90%, respectively, of Trimethylsi-lyl-di(timethylsiloxy)-silane. In conclusion, the N. sativa seed extract contains good phytochemicals, anti¬oxidant and varied antimicrobial activities against the test pathogens.

115-131

Authors: Jevšnik M., Raspor P.

Currently, food safety is managed through the HACCP system, and different good practices and food safety standards at different levels in food supply chain. The impact of food safety culture on the food sup¬ply chain is discussed at different levels and the realisation of it is achieved by various actors in complex food networks. Innovative approaches in the food supply chain have a positive impact by raising the level of employee qualifications and motivation to work according to the principles of food safety. The food business operator or person that is responsible for food safety is a key factor in identifying weaknesses in food safety, changing entrenched habits of employees, and introducing innovative approaches to effectively and rapidly respond to changes in the internal and external environments. This can build a new dimension of food safety, the so-called food safety culture, which is based on ethics in the field of food safety. As has been shown, the current maintenance of food safety in the food supply chain can easily break down, but the introduction of food safety culture can manage this issue and enhance food safety activities in food supply chains.

139-144

Authors: Al-Rawe A., Suleiman A. A.

Globally, cancer has been estimated to cause about 13% of all deaths in the world, especially in de¬veloping countries. Cancer cells are abnormal cells that disrupt the process of cell division, and there are more than 100 types of cancer. The diagnosis of cancer is still the most important factor in the success of cancer treatment. Treatment strategies of cancer may include radiation, chemotherapy, and surgery. This study was conducted to estimate microbiota counts in cancer patients, finding a method for detection and treatment follow up. Lactobacillus and Bifidobacterium counts were determined by qPCR depending on the standard curve from known bacterial counts obtained from probiotics. The main results of this study showed that the Lactobacillus count significantly increased in newly diagnosed cancer patients, while the count of Bifidobacterium decreased compared to the control. Also, chemotherapy led to a decrease in both bacteria counts, which may suggest supporting chemotherapy with probiotics.

153-162

Authors: Afolabi F. T., Ayodele E. O.

This study compared the yields of bioethanol from the fermentation of pretreated cassava peels using yeasts isolated from palm wine, and a pretreatment method with methanol + acid before solid-state fermen¬tation of cassava peels using Trichoderma reesei for 5 days optimally yielded 1.78 g/mL of reducing sugar. The hydrolysate was fermented for bioethanol production using Saccharomyces cerevisiae and Candida tropicalis. S. cerevisiae performed optimally at 30oC, pH 4.5, and produced ethanol with a concentration of about 40.72 g/L, while C. tropicalis produced 29.90 g/L of ethanol concentration at 35oC, and pH 5. Both yeast isolates took the same fermentation time of 96 h. In conclusion, cassava peels are agricultural waste that is a degradable material suitable to produce simple reducing sugars, which can be fermented by yeast to produce bioethanol. The yield of ethanol was higher for S. cerevisiae than C. tropicalis.

75-78

Authors: Savov, E., Kovachka, K., Trifonova, A., Kioseva, E., Strateva, T.

Intestinal carriage of extended spectrum β-lactamase Enterobacteriaceae (ESBL-E) and carbap¬enemase-producing Enterobacteriaceae (CPE) can persist for a long time (Huttner et al., 2019). Multi¬drug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa and their intestinal carriage is also a big problem, because studies in the last years have shown that the colonization with multidrug-resistant Gram-negative bacteria (MDR-GNB), especially in immunocompromised patients, increases the risk of infections (Tacconelli et al., 2019). Therefore, the evaluation of decolonization regimens with oral antibi¬otics and faecal microbiota transplantation (FMT) used for eradication of MDR-GNB in the gut is of great importance in reducing morbidity and mortality in these patients.

90-95

Authors: David, O. M., Adelowo, O. O., Theophilus, O., Adetan, O. N., Ojo-Bola, T., Owabumoye, J. B., Moroa, D. D.

Pichia kudriavzevii is commonly used in food processing, its association with human infection is very rare. In the few cases where it has been reported, it is rarely present in healthy individuals. This study investigated the incidence of Pichia kudriavzevii among patients on catheter in a tertiary institution in Ekiti State. A structured questionnaire was used to collect demographic data of the patients. Fifty-six non-repeat catheterized urine samples were collected from consented patients and both pathogenic factors and antifun¬gal resistance were determined among the Pichia kudriavzevii isolated. Out of the 56 urine samples tested, 15 (26.8%) were positive for P. kudriavzevii while 31 (73.2%) showed growth of other fungi, mostly of the genus Candida. Out of the antifungal agents tested against P. kudriavzevii, ketoconazole [n=11 (73.3%)] was the most effective followed by clotrimazole [n=7 (46.7%)] and nystatin [n=6 (40%)]. According to the outcomes of the present study, P. kudriavzevii appears to be associated with urinary catheter and with many virulence factors. The isolates were also resistant to first-line antifungal drugs in addition to the virulence factors. This yeast may emerge as another fungal pathogen especially among immunocompromised.

100-103

Authors: Villegas, J. A. A., Rodriguez, M. I., Rodriguez, S. P., J. Gutierrez, A. G.

The objective of this study was to identify strains of Escherichia coli producing extended spectrum beta-lactamases (ESBL) in urine cultures and to evaluate the patterns of resistance to certain antibiotics used in clinical practice as treatment of choice in the Valley of Toluca, Mexico. One hundred and fifty-five urine samples were obtained from people in the Toluca Valley, Mexico, under the necessary hygiene con¬ditions, 100 ml used to identify the pathogen and its resistance patterns were collected from each sample through an automated WalkAway method. In order to determine ESBL, a double disk technique was used. Nineteen ESLE-producing strains of E. coli were obtained, of which 100% showed resistance to ampicillin and cephalosporins, to tetracycline 93.75% resistance, levofloxacin 87.5% and ciprofloxacin 81.25%, and sensitivity of 100% to amikacin and carbapenemics. In conclusion, antibiotic resistance represents a major health problem. As the present study shows, ampicillin is a drug of choice for urinary tract infectioncaused by E. coli, but in the Toluca Valley the resistance to this antibiotic is 100% in ESBL-producing strains, which also show high resistance patterns to cephalosporins, quinolones, tetracycline and trimethoprim with sulfamethoxazole.

108-109

Authors: Akhtar, N., Nawaz, F., Idnan, M.

The main purpose of this letter is to raise concerns about the imminent spike in Covid-19 infection cases in Pakistan during the upcoming event of Eid Ul Adha, 2020, due to mass gathering of people in the cattle markets, especially from asymptomatic coronavirus carriers. As Pakistan is already facing insur¬mountable difficulties in managing Covid-19 due to its limited healthcare infrastructure, a more severe coronavirus-19 outbreak is expected in the post-Eid Ul Adha days, especially in big cities like Lahore, Karachi and Islamabad, posing a new challenge for the authorities.

43-44

Authors: Mayer, F.

In recent years more people die each year from cardiovascular diseases (CVDs) than from any other cause and 17.7 million people died from CVDs in 2015, representing about one third of all global deaths ac¬cording to the WHO. Streptokinase is a thrombolytic agent with systemic fibrinolytic effect. It is a non-en¬zymatic protein produced by β haemolytic streptococci and activates the fibrinolytic system indirectly. Streptokinase is used widely and routinely for treatment of acute myocardial infarctions. In this study strep¬tokinase gene from Streptococcus pyogenes C1 was cloned in pET28a vector and transferred to Escherichia coli BL21. Expressed protein was purified by Ni-NTA column and visualized with SDS-PAGE. Streptoki¬nase (SK) coding DNA fragment was amplified from S. pyogenes C1 genomic DNA by PCR. The amplifi¬cation products were inserted into the cloning and expression vector pET28a(+). Recombinant pET28a(+) plasmid with recSK gene were then introduced to E. coli BL21 (DE3) by electroporation. The streptokinase encoded by the plasmid pET28a(+) contains the mature streptokinase with the 6X histidine-tag.

53-58

Authors: Adeogun, O. S., David, O. M., Adesina, A. O., Babalola, T. O.

Hepatitis B virus (HBV) and Hepatitis C virus (HCV) infections cause chronic hepatitis in humans. The co-infections of these viruses with human immunodeficiency virus (HIV) have increased the burden, especially in the resource-poor nations of the world. In this study we determine the burden of HBV and/ or HCV with HIV among pregnant women attending selected General Hospitals in Ondo State, Nigeria. The sera of consented subjects were collected and screened for the presence of HBV using enzyme-linked Immunosorbent Assay (ELISA) kits while HIV was detected using WHO approved rapid kit and its confir-mation was done with Western blot assay. Out of two thousand, nine hundred ninety-eight (2.998) pregnant women screened, the numbers positive for HBV (HBsAg), HCV (antibody) and HIV (antibody) were 60, 54 and 28, respectively. The highest HIV seroprevalence was detected among women in the age group of 35- 39 years. The seroprevalence of co-infections HBV and HCV was 0.07 % while those of HIV and HBV, and HIV and HCV were 0.03 % each. None of the subjects had the three viruses. The difference in demographic characteristics of the study population in the study areas might explain the varying results observed in this study. Pregnant women should not only be screened for HIV but also for both Hepatitis B and C infections during their first ante-natal visit.

63-67

Authors: Shilev, S.

Arsenic is a common contaminant in soils, affecting soil microbiome and all soil organisms. The present study examined arsenate tolerance of two Saccharomyces cerevisiae strains isolated from contami¬nated soil. Their tolerance to sodium arsenate (AsV) was studied in a liquid medium for 24 hours, while the ability of the populations to reduce their intracellular arsenic content was subsequently investigated through kinetic studies of arsenate transport at 33.3, 133.2, and 266.4 μM of AsV. The dependence of tolerance on the efflux system was demonstrated by the use of amiloride hydrochloride, which is known as a suppressor of ion transport through the cell membrane. The maximum concentration tolerated by S. cerevisiae AS09 was found to be about 72.8% lower than that by the tolerant S. cerevisiae AS07. The influx and efflux of arsenate across the cell membranes of both strains were dependent on the concentration of metalloid in the medium and on the anion net balance. Both strains rapidly increased their internal As concentration to a maximum point, although only the tolerant strain was able to decrease it subsequently in all concentrations used. When the highest concentration was applied, the cells of the non-tolerant strain were found to be dead. When amiloride hydrochloride was used it was found that the tolerant cells behaved like sensitive cells, and at 266.4 μM the cells of both strains were found to be dead, because the extrusion of the toxic anion was interrupted. Kinetic differences in arsenate transport through the cell membrane explain the different degrees of tolerance of the studied strains.