فصلنامه زیست شناسی میکروارگانیسم ها
پیاپی 48 (Winter 2024)

Nitrogen compounds are used in various industries and cause pollution of water and soil. As a result, the bioremediation of nitrogen compounds from the environment becomes an important issue. In this way, the use of microorganisms as a consortium has enhanced bioremediation. This study aimed to remove inorganic nitrogen forms by heterotrophic nitrifying-aerobic denitrifying (HN-AD) bacterial consortium and compare it to pure cultures. HN-AD bacteria were isolated from soil and aquarium water and identified. After that, the bacterial consortium was prepared from two isolated bacteria and two strains from the microbiological culture collection of the University of Isfahan (Iran). The ability to remove ammonium, nitrite, and nitrate was assayed using spectrophotometry for both pure cultures and the consortium. Pseudomonas mendocina AquaN and Pseudomonas monteilii Nht were isolated and identified for their efficient capabilities in HN-AD. The bacterial consortium including two isolated bacteria and Acinetobacter calcoaceticus SCC2, Rhodococcus erythropolis R1 was able to consume NH4+-N (85.6 mg.L-1), NO2--N (23.1 mg.L-1), and NO3--N (102.5 mg.L-1) as sole nitrogen sources by removal efficiencies 98.4%, 90.5%, and 40.0%, respectively that were better than pure cultures performances. Specifically, the consortium was capable of removing 250 to 2045 mg.L-1 NH4+-N with up to 95% efficiency within 48h.Discussion and The compatibility of the strains as a consortium was considerable and the bacterial consortium showed significant performances in nitrogen removal, especially the removal of 2045 mg.L-1 NH4+-N. These findings indicated the bacterial consortium could be a promising candidate for the treatment of high-strength ammonium wastewater.

Extracellular laccases are constitutively formed in fungi, particularly from basidiomycetes, during secondary metabolism. However, the enzymes are produced in relatively small amounts. Due to their wide application, the productivity improvement process of laccase is important for potential industrial applications. Interspecific interaction of lignolytic fungi with other fungi or bacteria is a technique to improve the production of laccase in a liquid state. In this research, the interspecific interaction of a yeast, Rhodotorula mucilaginosa, with white-rot fungi, Pleurotus florida, was evaluated in submerged fermentation using potato dextrose broth. The yeast cells at 103, 105, and 107 CFU mL-1 concentrations were added into 1-, 3-, 5- and 8-day cultures of P. florida. To investigate the effect of temperature on R. mucilaginosa cells or its metabolites for laccase enhancement, yeast cells were exposed to different temperatures (1 h), including room temperature (control), 70 ◦C, and 121 ◦C (autoclaved). Then, 3% of the suspension (v/v) was added to the P. florida culture. The laccase activity was assessed by the colorimetric method at 436 nm. The results showed that, in comparison to control, the laccase activity was enhanced 4.5 times during P. florida yeast interactions in potato dextrose broth medium. Production of the enzyme was significantly affected by the yeast cell concentration and the inoculation time of R. mucilaginosa in the co-culture of P. florida. Maximum enzyme production was achieved when the 5-day P. florida culture inoculated with 105 CFU mL-1 of R. mucilaginosa. The addition of autoclaved (121 ◦C) yeast cells to P. florida culture did not significantly increase laccase production as compared to control (monocultures of P. florida), although the lowest sterilization temperature (70 ◦C) had a stimulatory effect on laccase production.Discussion and The results of the study showed the capability of yeast to increase the laccase production by P. florida in dual cultures. The responses of the laccase production could be affected by the inoculation time (after P. florida cultivation) and R. mucilaginosa cell concentration. The interactions needed the live stimulator cells and the stimulatory compounds were temperature-sensitive.

Tannins are a group of polyphenolic compounds that are widely present in plants as an anti-nutritional factor. The rumen of wild ruminants contains novel microbes that detoxify antinutrients and improve feed digestion. The present study evaluated tannase-producing bacteria isolated from the rumen of Fallow deer (Dama dama), livestock potential feed additives. Tannase-producer bacteria (TPBs) were isolated from the rumen using a 2% tannic acid- plate and tannase activity (TAA) assayed by the spectrophotometer method. The bacterial DNA was extracted through boiling and amplified using a PCR reaction. The Sanger technique and BLAST software were used to identify the strains. Antibacterial (ABA) and antibiogram tests were performed by the disc diffusion method, and the acid and bile resistance of isolates were examined using broth cultures. The results indicated that TPBs belonged to Klebsiella, Enterobacter, and Escherichia genera. Escherichia fergusonii GHMGHE44 (9.39 Uml-1) and Enterobacter cloacae GHMGHE26 (1.79 Uml-1) were the strongest and weakest tannin degraders (p<0.01). Among the isolates, bile and acid resistance were insignificant (p>0.01) but E. fergusonii GHMGHE28 (9.48 CFU ml-1) had a significant survival rate compared to E. cloacae GHMGHE25 (9.07 CFU ml-1) at pH of 7 (p<0.01). Also, K. pneumoniae subsp. rhinoscleromatis GHMGHE27 (32.66 mm), E. coli GHMGHE47 (40.66 mm), and E. fergusonii GHMGHE48 (24.66 mm) were potently suppressed the pathogen E. Coli, S. aureus and P. aeruginosa, respectively (p<0.01). Against used antibiotics, E. asburiae GHMGHE22 was the most sensitive isolate while others showed diverse reactions (p<0.01).Discussion and The findings showed that TPBs have the potential to study as commercial animal feed additives (AFA).

Lipases play a crucial role as biocatalysts, specifically in breaking down lipid ester bonds. Among these biocatalysts, bacterial lipases stand out for their ability to hydrolyze a wide range of substrates, while also being more stable and cost-effective to produce. Unfortunately, the discharge of effluents from oil refineries into surface waters leads to significant environmental pollution. In light of this, the objective of this study is to isolate and identify lipase-producing bacteria from effluents contaminated with oily compounds. To identify lipase-producing strains, specific culture media such as tributyrin agar were used, and the secretion of lipase around the bacterial colonies was observed. The isolates were then subjected to biochemical evaluation to determine the strains with the highest enzyme activity. To identify the bacterial strains accurately, PCR was performed targeting conserved 16S rRNA sequences. The PCR products were sequenced and analyzed using the BLAST method for further analysis and identification. To identify lipase-producing strains, different dilutions of contaminated effluent and soil samples were cultured. Four colonies with the widest transparent halo around them were isolated and purified (R1-R4). Strain R2 exhibited the highest lipase activity with a value of 3.452u/ml, whereas strain R4 displayed the lowest activity at 1.996u/ml. After conducting the molecular evaluation of the isolated strains, it was revealed that strain R1 belonged to Acinetobacter junii strain B2, strain R2 was identified as Rummeliibacillus pycnus strain NBRC 101231, and strain R3 was categorized as Pseudomonas aeruginosa strain HX-2.Discussion and The study identifies a promising local bacterial candidate that holds potential for industrial-scale production of lipase.

This study aimed to investigate the synergistic and separate cytotoxicity effects of carboplatin (a chemotherapy medication) and Lactobacillus plantarum cell lysate supernatant (CLS) in the SK-OV-3 ovarian cancer cell line and the expression change of apoptotic Bax and anti-apoptotic Bcl-2 genes. L. Plantarum CLS at concentrations of 0.05, 0.1, 0.15, 0.25, 0.5, 1, 1.25, and 1.5 mg/ml and carboplatin at concentrations of 0.1, 0.5, 1, 2, 2.5, 5, 10, 20, 40, and 50 μg/ml were prepared. Separate and synergistic toxicity effects of carboplatin and L. Plantarum CLS at different concentrations were investigated on the SK-OV-3 cell line at intervals of 24, 48, and 72 h using the MTT method. Also, the expression level of Bax and Bcl-2 genes in the treated SK-OV-3 cell line was analyzed using Real-time PCR. In the current study, the highest increases of toxicities in the separate and synergistic application of carboplatin and L. Plantarum CLS were seen after 48-h treatment against cancer cells. These toxicities were time-dependent, and with increasing time from 24 to 72 h, their cytotoxicity increased. The results of the MTT test showed that drug and probiotics synergism could cause the highest decrease in the survival rate of the SK-OV-3 cell line in 72, 48, and 24 h, respectively. This synergism led to a 2.8-fold decrease in the expression of the Bcl-2 gene and a 3.5-fold increase in the Bax gene compared to the control group. Carboplatin alone decreased Bcl-2 by 1.4 times and increased Bax by 1.5 times, and CLS alone decreased Bcl-2 by 3.2 times and increased Bax by 1.2 times.Discussion and We concluded the combination of an L. Plantarum CLS (0.1 mg/ml) and carboplatin (0.5 μg/ml) has induced apoptosis in the SK-OV-3 cell line. L. plantarum. CLS can be used as adjunctive therapy with carboplatin through increased toxicity and changes in apoptosis gene expressions.

Global municipal solid waste generation is growing progressively due to social urbanization. Fruit and vegetable waste are a significant part of solid waste. This waste can be recovered to produce biofuels. Saccharomyces cerevisiae is consumed as a first-choice microorganism for industrial processes of alcoholic fermentation. The potential of ethanol production by S. cerevisiae PTCC 1212 on a laboratory scale was investigated using fruit and vegetable wastes over solid-state fermentation (SSF) using a colorimetric distilling system. First, we have estimated the ethanol production potential of solid waste substrates taken from the Shahrekord Center of Fruits and Vegetables. Next, and over-optimization experiments, fermentation parameters for ethanol production and yield including substrate type, pH, humidity, inoculum volume, and time of fermentation were evaluated using the Taguchi statistical method. Bioethanol assay was done by the distillation-colorimetric method and sugar consumption was determined using the DNS colorimetric method. Bio-ethanol production contents from solid waste substrates including fruit mix, carrot, potato, cattle food, eating vegetable, and beet molasses as an alcoholic fermentation additive were 2.8, 2.3, 0.98, 0.56, 0.07, and 3.5 (w/v), respectively. The optimized conditions for ethanol production were 4 days of fermentation, pH 6, 90% humidity, and 5% inoculum volume. The ethanol achievement in the final test based on optimized parameters was up to 3.3%. The optimized conditions for the best ethanol yield (ethanol per one gram of substrate) were, pH =5, humidity level as natural (without the addition of water) and substrate mixed fruits plus molasses.Discussion and High sugar rate conversion showed appropriate efficiency in the fermentation process and fruit and vegetable wastes have an exciting potential for bio-ethanol production in solid-state fermentation. It could be considered for environmental challenges with garbage management. Moreover, adding molasses seems to be an appropriate supplement for boosting the production of ethanol.

Lactic acid bacteria (LAB), as the main dairy starters, play an essential role in the production of volatile compounds such as proteolytic and lipolytic enzymes involved in cheese processing, suppression of pathogenic microorganisms, formation of curdling tissue, and creation of a fresh acidic flavor. In this study, the LABs were isolated from fourteen samples of traditional cheeses in different part of Iran. The isolates with the highest cheese production capacities were selected and subsequently various factors including pH and temperature were evaluated on their activity. Besides, the viability of strains, which were used to produce traditional cheeses, under microencapsulation and gastric simulation conditions was also investigated. Finally, the best LAB strains (BCC7 and BCC10), with desirable characteristics for cheese production, were molecularly identified by using the 16srDNA test. This study showed that the survival rate of BCC7 and BCC10 isolates microencapsulated with sodium alginate/chitosan were higher than free cells in the storage condition of -80 °C after six weeks by 23.50% and 20.78%, respectively. Moreover, the quantification of the activity of BCC7 and BCC10 strains at a temperature of 4 °C yielded 11 107 CFU/ml and 9 107 CFU/ml, respectively; exhibiting a greater activity than that observed at a temperature of 28 °C. Furthermore, the preservation of their morphological and biochemical properties was observed.Discussion and The present study determined the sequences of the most efficient lactic acid strains, and subsequent analyses indicated that the BCC7 and BCC10 strains isolated from native cheese samples, were corresponded to Enterococcus faecium strains SKL-4 and 276-18, respectively. Therefore, these two strains are good candidate to introduce to the market as high-quality starters for dairy industries.