Mesophilic Microorganisms Research Articles

Lignocellulolytic extremozymes and their biotechnological applications.

Lignocellulolytic enzymes are used in different industrial and environmental processes. The rigorous operating circumstances of these industries, however, might prevent these enzymes from performing as intended. On the other side, extremozymes are enzymes produced by extremophiles that can function in extremely acidic or basic; hot or cold; under high or low salinity conditions. These severe conditions might denature the normal enzymes that are produced by mesophilic microorganisms. The increased stability of these enzymes has been contributed to a number of conformational modifications in their structures. These modifications may result from a few amino acid substitutions, an improved hydrophobic core, the existence of extra ion pairs and salt bridges, an increase in compactness, or an increase in positively charged amino acids. These enzymes are the best option for industrial and bioremediation activities that must be carried out under difficult conditions due to their improved stability. The review, therefore, discusses lignocellulolytic extremozymes, their structure and mechanisms along with industrial and biotechnological applications.

Reduction of PDO Pecorino Siciliano cheese making duration: Microbial dynamics and quality attributes deriving from replacing whey permeate with hot water during cooking

This work was carried out with the aim to reduce the transformation duration of Protected Designation of Origin (PDO) Pecorino Siciliano cheese. To this purpose, the cooking in hot water (experimental production, EXP) was compared to the traditional cheese cooking under whey permeate (control production, CTR). The microbiological composition of under rind (UR) and core (Co) section of CTR and EXP cheeses was determined by a combined culture-dependent and -independent approach. Total mesophilic microorganisms and lactic acid bacteria (LAB) present in raw ewes' milk (5.0 log CFU/mL) increased during cheese making and reached values of about 8.0 log CFU/g in both sections (UR and Co) of 5-month ripened cheeses of both productions (CTR and EXP) monitored. The identification of the viable LAB populations in ripened cheeses showed that Enterococcus, Lacticaseibacillus, Lactiplantibacillus, Levilactobacillus, Limosilactobacillus and Streptococcus dominated UR and Co sections of all cheeses. MiSeq Illumina analysis demonstrated that LAB populations (lactobacilli, lactococci and streptococci) dominated the bacterial community of cheeses at 95.63–98.41 % of relative abundance. The two different cooking operations did not influence the physicochemical characteristics of PDO Pecorino Siciliano cheeses. Sensory evaluation performed by artificial senses analysis and trained panelists confirmed that the modification of PDO Pecorino Siciliano cheese production protocol did not significantly affect product characteristics and overall acceptance. Thus, data of this work confirmed that cooking under hot water allowed to reduce transformation duration and safeguard typicality of PDO Pecorino Siciliano cheese.

The wooden shelf surface and cheese rind mutually exchange microbiota during the traditional ripening process

The rind acts as a protective barrier for internally-bacterial ripened cheeses. Unlike surface-inoculated smear cheeses, centripetal maturation is not assumed to occur in these cheeses. This research was aimed to evaluate the microbial diversity of the wooden shelves used for the ripening of Protected Denomination of Origin (PDO) Pecorino di Filiano and Protected Geographical Indication (PGI) Canestrato di Moliterno cheeses. The microorganisms associated with the rind of these cheeses were also investigated. Both wooden shelf surfaces and cheese rinds were sampled by brushing method to collect their biofilms. Wooden shelves showed levels of total mesophilic microorganisms (TMM) between 5.6 and 7.2 log CFU/cm2, while cheese rinds between 6.1 and 7.8 log CFU/cm2. The major dairy pathogens (Salmonella spp., Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus) were never detected, while mesophilic and thermophilic bacteria dominated the surfaces of all wooden shelves and cheese rinds. LAB community was represented by Enterococcus spp., Leuconostoc spp., and Marinilactibacillus spp. Among yeasts, Debaryomyces spp., Candida spp., were identified, while Aspergillus spp., and Penicillium spp., dominated the community of filamentous fungi. MiSeq Illumina analysis identified 15 phyla, 13 classes, 28 orders, 54 families, and 56 genera among bacteria. Staphylococcus spp. was identified from all wooden surfaces, with a maximum abundance of 71 %. Brevibacterium, Corynebacterium and halophilic bacteria were detected in almost all samples. Regarding fungi, wooden shelves mainly hosted Aspergillus, Penicillium and Debaryomyces hansenii, while cheese rinds especially Penicillium and D. hansenii. Alpha diversity confirmed a strict correlation between the microbiota of wooden shelves and that of cheese rinds for the majority of factories. This study confirmed that the wooden shelves used for cheese ripening are microbiologically active and represent safe systems. Furthermore, the results of this work clarified the transfer flow between wooden shelves and PDO Pecorino di Filiano and PGI Canestrato di Moliterno cheese surfaces: smear-active microorganisms are mainly transferred from wooden shelves to cheese rind, which potentially contribute to the development of the final organoleptic characteristics; meanwhile, cheeses transfer LAB that are potentially involved in defining the safety aspects of the shelves.

Effect of Inulin Addition on Physicochemical, Microbiological, Textural, and Sensorial Characteristics of Fermented Butifarra with Lactobacillus sakei

Butifarra, with the addition of inulin, was produced for the first time. The objective of this study was to investigate the effect of inulin in butifarra fermented with Lactobacillus sakei ATCC® 15521™ on physicochemical properties, instrumental texture, microbiology, and sensory evaluation. Initially, fermented butifarra was prepared with the addition of 5% and 7.5% inulin and a control butifarra was prepared without inulin addition. The butifarra was analyzed by physicochemical, microbiological, instrumental texture, and sensory evaluation. The results indicated that the analysis of physicochemical properties, fat, protein, and ash content showed no significant differences between the experimental and control butifarra (p > 0.05); in other words, this type of fiber did not cause alterations in the butifarra. The mesophilic microorganism count, total and fecal coliforms, and positive staphylococcus were assessed according to Colombian Technical Standard 1325 of 2008. The hardness of the butifarra with higher inulin content on day 9 was, on average, ~55% greater than the control. The adhesiveness increased in each formulation as the days of fermentation increased, showing significant differences relative to the control. In general, the best sensory properties evaluated were related to the butifarra samples with higher inulin content in the formulation, so it is established that inulin did not alter the sensory properties of the butifarra, but rather potentiated the sensory attributes, making it suitable for use in fermented meat formulations. It can be stated that the addition of inulin to fermented butifarra is possible.

Inoculum of a Native Microbial Starter Cocktail to Optimize Fine-Aroma Cocoa (Theobroma cacao) Bean Fermentation

Fine-aroma cocoa (Theobroma cacao) is one of Ecuador’s most iconic export products and comprises 63% of world production. Nevertheless, few advances have been made to improve fermentation processes that might benefit the development of chocolate’s organoleptic characteristics. The study of starter cultures, which seek to improve organoleptic properties or decrease fermentation time, has been investigated in other countries. The aim of this study was to analyze the effect of a native microbial cocktail based on two yeasts (Torulaspora delbrueckii and Hanseniaspora uvarum), a lactic acid bacterium (LAB) (Limosilactobacillus plantarum), and an acetic acid bacterium (AAB) (Acetobacter ghanensis) inoculated at the beginning of the fermentative process while tracking physical and biochemical variables, microbial population dynamics, and bean fermentation time. The starter culture caused changes in sugar and acid content and increased polyphenols, which in turn generated temperature and pH changes in the dough. The dynamics of yeast, AAB, and mesophilic microorganisms remain higher than the controls throughout the process. A decrease in filamentous fungi that affect the flavor and quality of beans was observed due to the production of acetic acid or secondary metabolites from yeasts and LAB, and resulted in 24% greater fermentation than spontaneous fermentation in only 96 h.

Nitrocellulose-containing sediment as renewable resource for hydrogen and high-pure carbon production

Nitrocellulose accumulated in sludge accumulators does not undergo any changes and remains explosive for decades but it can be used as initial recourse for H2 and nanocarbon production through biogas. Anaerobic biotransformation of waste with a nitrocellulose content of about 75% with native microflora, consortia of mesophilic or thermophilic microorganisms from industrial bioreactors under various volume loading of microorganisms and temperature conditions has been studied. Stimulation by an additional source of biogenic elements and the development of native microflora made it possible to reduce the concentration of nitrocellulose by 44% at 35 °C in 100 days. With a biocatalyst volume loading of 30% at 35 °C with mesophilic biocatalyst 39% of nitrocellulose (with 50% initial volume loading) was conversed to biogas, at 55 °C with thermophilic biocatalyst-99%. The rate constant of decomposition of nitrocellulose using a thermophilic biocatalyst was 0.0248 day−1, while the half–life of nitrocellulose was 28 days.

Elaboración de conservas de pasta untable ahumada a partir de recortes de filetes de trucha Oncorhynchus mykiss

The objective of this study was to elaboration of smoked spreadable paste canned from Oncorhynchus mykiss trout fillet trimmings. The product was made from the trimmings from the process of frozen trout fillets. The study consisted of 18 experimental tests, which were subjected to a test to measure the degree of satisfaction, the winning experimental test being F2A2. Through this test, it was possible to find out the optimal formulation and the smoke application method for the elaboration of smoked spreadable preserves from trout fillet trimmings Oncorhynchus mykiss. The heat treatment time found for our preserve was 62 minutes at 115.28 °C, obtaining a minimum F0 value of 6.11 minutes, thus achieving commercial sterility. The proximal chemical analysis reported results of protein (8.85%), fat (21.63%), moisture (59.96%) and ash (1.85%). The commercial sterility results reported the absence of mesophilic and thermophilic microorganisms; therefore, this product was called commercially sterile.

Supercritical CO2 Processing of White Grape Must as a Strategy to Reduce the Addition of SO2.

In winemaking, sulfur dioxide addition is the most common procedure to prevent enzymatic and microbial alterations. However, the enological industry looks for safer alternatives to preserve enological products, and high-pressure treatments with supercritical CO2 are a suitable alternative. This study evaluates the effectiveness of this process in the stabilization and preservation of white grape must, studying the influence of time, pressure, and CO2 percentage on must characteristics. In spite of the percentage of CO2 turned out to be the variable that affects the most the process, no remarkable differences were observed in pH, acidity, and color intensity between untreated and treated musts. Moreover, this technique has proven to be very efficient in the reduction of aerobic mesophilic microorganisms as well as in the reduction of residual polyphenol oxidase activities, being lower than those obtained with SO2 addition (60 and 160 mg/L). Based on the results, the most convenient conditions were 100 bar and 10% CO2, for 10 min treatment.

A comparative approach to confirm antibiotic-resistant microbes in the cryosphere.

Antibiotic-resistant microbes pose one of the biggest challenges of the current century. While areas with proximity to human impact are closely studied, a lot is yet to learn about antimicrobial resistance in remote regions like the cryosphere. Nowadays, antibiotic (AB) resistance is considered a pollution that has reached the Earth's most pristine areas. However, monitoring of resistant environmental bacteria therein faces several challenges that inhibit scientific progress in this field. Due to many cultivation-based antibiotic susceptibility tests being optimized for mesophilic pathogenic microorganisms, many researchers opt for expensive molecular biological approaches to detect antibiotic resistance in the cryosphere. However, some disadvantages of these methods prohibit effective comprehensive monitoring of resistant bacteria in pristine areas, hence we suggest established cultivation-based approaches when looking for antimicrobial resistance in the cryosphere. In this study, we compared two common antibiotic susceptibility tests and optimized them to meet the needs of psychrophilic microorganisms. The resulting cultures thereof originated from cryospheric habitats with differing anthropogenic impacts. The results show that these methods are applicable to detect antibiotic resistance in cryospheric habitats and could potentially increase the comparability between studies.

Validation of Pasteurisation Temperatures for a Tomato-Oil Homogenate (salmorejo) Processed by Radiofrequency or Conventional Continuous Heating.

Salmorejo is a viscous homogenate based on tomato, olive oil and breadcrumbs commercialised as a "fresh-like" pasteurised-chilled purée. Due to its penetration, dielectric heating by radiofrequency (RF) might improve pasteurisation results of conventional heating (CH). The objective was to validate the pasteurisation temperature (70-100 °C, at 5 °C intervals) for salmorejo processed by RF (operating at 27.12 MHz for 9.08 s) or conventional (for 10.9 s) continuous heating. The main heat-induced changes include: orangeness, flavour homogenisation, loss of freshness, thickening, loss of vitamin C and lipid oxidation. Both CH and RF equivalent treatments allowed a strong reduction of total and sporulated mesophilic microorganisms and an adequate inhibition of the pectin methylesterase, peroxidase and, to a lesser extent, polyphenol oxidase but did not inhibit the polygalacturonase enzyme. Pasteurisation at 80 °C provided a good equilibrium in levels of microbiological and enzymatic inhibition and thermal damage to the product. Increasing this temperature does not improve enzyme inactivation levels and salmorejo may become overheated. A "fresh-like" good-quality salmorejo can be obtained using either conventional or radiofrequency pasteurisers.

Low-temperature thermally enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soil: Effects on fate, toxicity and bacterial communities

Remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using thermal desorption technology typically requires very high temperatures, necessitating coupled microbial treatment for energy and cost reduction. This study investigated the fate and toxicity of PAHs as well as the responses of microbial communities following thermal treatment within a low temperature range. The optimal temperature for PAH mineralization was 20–28 °C, within the growth range of most mesophilic microorganisms. By contrast, 50 °C treatment almost completely inhibited PAH mineralization but resulted in the greatest detoxification effect particularly for cardiotoxicity and nephrotoxicity. A potential increase in toxicity was observed at 28 °C. Co-metabolism and non-extractable residue formation may play an interdependent role in thermally enhanced bioremediation. Moreover, alterations in bacterial communities were strongly associated with PAH mineralization and zebrafish toxicity, revealing that soil microorganisms play a direct role in PAH mineralization and served as ecological receptors reflecting changes in toxicity. Network analysis revealed that Firmicutes formed specific ecological communities at high temperature, whereas Acidobacteria and Proteobacteria act as primary PAH degraders at moderate temperature. These findings will enable better integration of strategies for thermal and microbial treatments in soil remediation.

Deleterious Effects of Polypropylene Microplastic Ingestion in Nile Tilapia (Oreochromis niloticus).

The effect of daily ingestion of polypropylene microplastic on the health of tilapia, Oreochromis niloticus, was evaluated. 60 fish (± 200g) were placed in 6 aquariums (n = 10, 100L each), constituting the following treatments: Control (without the addition of polymer), fed with 100 and 500µg of polypropylene/kg of body weight (b.w.), respectively. After 30 days of feeding, the animals were submitted to blood collection for hemogram and biochemical study and later euthanized for gut microbiological analysis, somatic index of liver, spleen, heart, kidney, stomach, and intestine. In the serum biochemical study, an increase in cholesterol and serum Aspartate Aminotransferase (AST) activity levels was observed in animals treated with 500µg of polypropylene. Tilapia-fed polypropylene in the diet showed an increase in thrombocyte and total leukocyte counts, marked by a significant increase in the number of circulating lymphocytes. The results of the somatic study revealed a significant increase in the stomach, liver, and heart of tilapia fed with the polymer. Increase in the number of Gram-negative microorganisms and decrease in mesophilic aerobic microorganisms were observed in the gut of fish exposed to the polymer, including a dose-response effect was observed for these analyses. Therefore, tilapias fed daily with diets containing polypropylene for 30 consecutive days showed deleterious effects, resulting in systemic inflammatory disturbs by altering liver functions, leukocyte profile, and organ morphometry, as well as changes in the intestinal microbiota. Such results demonstrate the impairment of fish health, highlighting the need for further studies that evaluate the impact of microplastics on aquatic organisms.

Quantitative characterization of microbial load in wild-harvested edible insects of Nagaland, India

Aim: To analyze the microbial load in raw and roasted insects in an attempt to determine the efficiency of heat treatment in removing the microbial load. Methodology: Fresh as well as roasted (over low flame for 15 min) insect samples were used to determine the microbial contaminants. Crushed insect samples were suspended in sterile half-strength nutrient broth solution and were further serially diluted 10-fold (up to 10-10) in isotonic half-strength nutrient broth solution. The total number of aerobic mesophilic microorganisms were determined on plate count agar and expressed as log Cfu g-1. Results: Differences in the number of microbial colonies were observed in fresh and roasted samples. The microbial load ranged from 6.30-8.75 log Cfu g-1 and showed that the highest microbial colonies were present in the fresh samples. The average log Cfu g-1 in fresh insect samples (7.57±0.87) was significantly higher (P<0.05) as compared to roasted samples (7.07±0.76). Interpretation: Edible insects require proper processing before consumption to reduce microbial contamination and further study is needed to identify specific microbes/food pathogens to develop microbial quality and parameters to ensure consumer safety. Key words: Alternative food, Edible insects, Food safety, Microbial contaminants, Traditional foods

Uniquely low stable iron isotopic signatures in deep marine sediments caused by Rayleigh distillation

Dissimilatory iron reduction (DIR) is suggested to be one of the earliest forms of microbial respiration. It plays an important role in the biogeochemical cycling of iron in modern and ancient sediments. Since microbial iron cycling is typically accompanied by iron isotope fractionation, stable iron isotopes are used as tracer for biological activity. Here we present iron isotope data for dissolved and sequentially extracted sedimentary iron pools from deep and hot subseafloor sediments retrieved in the Nankai Trough off Japan. Dissolved iron (Fe(II)aq) is isotopically light throughout the ferruginous sediment interval but some samples have exceptionally light isotope values. Such light values have never been reported in natural marine environments and cannot be solely attributed to DIR. We show that the light isotope values are best explained by a Rayleigh distillation model where Fe(II)aq is continuously removed from the pore water by adsorption onto iron (oxyhydr)oxide surfaces. While the microbially mediated Fe(II)aq release has ceased due to an increase in temperature beyond the threshold of mesophilic microorganisms, the abiotic adsorptive Fe(II)aq removal continued, leading to uniquely light isotope values. These findings have important implications for the interpretation of dissolved iron isotope data especially in deep subseafloor sediments.

Growth of Soil Saprophytes

The purpose of the research was to study the procedure of saprotrophic or lyotropic nutrients for extracellular absorption concerned with an emphasis on processing of decaying natural count. The research question was does saprotrophs become maximum in the presence of fungi and soil micro-organism. The method concerned samples of mycelium to increase a part of fungus or fungus-like bacterial colony, consisted of a mass of branching hyphae. The results confirmed fungal colonies were composed of mycelium have been determined in and on soil and substrates. It concluded unicellular microorganisms have been commonplace level in the composition stages. Initial decomposition become completed with the aid of using mesophilic microorganism dissolution of soluble and degradable compounds.

Reduction of Pericarp Browning and Microbial Spoilage on Litchi Fruits in Modified Atmosphere Packaging

The pericarp browning and postharvest microbiological decay of litchi fruit (Litchi chinensis Sonn cv Kwai Mai) significantly reduce its commercial potential in the fresh market. In this study, different combinations of modified atmosphere packaging (MAP) were applied at 5 ± 1 °C based on the use of natural gases that are innocuous to human health and an alternative to commercially adopted sulfur dioxide (SO2) treatment. The results showed that control fruits, after 6 days of storage, begin to show the first symptoms of decay, revealed by the appearance of lesions and microbial infections determined by total mesophilic microorganisms and molds. This is not the case in the MAP-treated fruits and the MAP 3-treated (5% O2 + 20% CO2 + 75% N2) fruits that show the best results. The control fruits, moreover, turned completely brown by the end of the storage period. The MAP 3 treatment was the most effective in preventing browning and the loss of the red pericarp color and vitamin content and in maintaining acceptable SSC/TA levels and flavor. In addition, a microbiological analysis revealed that all the MAP-treated litchi fruits did not harbor undesirable microorganisms during the entire cold storage period. In conclusion, the MAP 3 conditions delayed pericarp browning and maintained the better organoleptic quality of litchi fruits.

Metagenomic, microbiological, chemical and sensory profiling of Caciocavallo Podolico Lucano cheese

In this study, Caciocavallo Podolico Lucano (CPL) cheese was deeply characterized for its bacterial community, chemical composition and sensory aspects. The entire cheese making process (from milk collection to ripened cheese) was performed by strictly applying the traditional protocol for CPL production in four dairy factories (A–D) representative of the production area. The vat made of wood represents the main transformation tool for CPL cheese production and the biofilms hosted onto the internal surfaces of all vats analyzed in this study were dominated by lactic acid bacteria. Total mesophilic microorganisms present in bulk milk (4.7–5.0 log CFU/ml) increased consistently after contact with the wooden vat surfaces (5.4–6.4 log CFU/ml). The application of Illumina sequencing technology identified barely 18 taxonomic groups among processed samples; streptococci and lactobacilli constituted the major groups of the wooden vat biofilms [94.74–99.70 % of relative abundance (RA)], while lactobacilli dominated almost entirely (94.19–100 % of total RA) the bacterial community of ripened cheeses. Except coagulase positive staphylococci, undesirable bacteria were undetectable. Among chemical parameters, significant variations were registered for unsaturated, monounsaturated, polyunsaturated fatty acids and antioxidant properties (significantly lower for CPL cheeses produced in factory B). The cheeses from factories A, C and D were characterized by a higher lactic acid and persistence smell attributes than factory B. This work indicated that the strict application of CPL cheese making protocol harmonized the main microbiological, physicochemical and sensory parameters of the final cheeses produced in the four factories investigated.

Effect of heat treatment on the content of microorganisms in drinking milk

The microflora of raw milk is in the center of constant attention at the enterprises where it is processed. Since the microbiota of pasteurized milk is determined by the percentage of heat-resistant bacteria that are present in the milk raw material. Defects during storage are associated with the development of residual microflora of pasteurized products. The aim of the work was to determine the quantitative changes in milk microflora using different pasteurization temperatures. Pasteurization of raw milk of the first and extra grades was carried out at t = +72 °С and t = +91 °С with a holding time of 15–20 s. In pasteurized and raw milk, the residual amount of microorganisms of different groups was determined: mesophilic, psychrotrophic, lactic acid, heat-resistant, and spore-forming. It was found that in raw milk before pasteurization, the main part of the microflora was psychrotrophic and mesophilic microorganisms up to 70%, the share of lactic acid microbiota was up to 25%, heat-resistant and spore-forming bacteria were 4% and 0.8%, respectively. The temperature regime of heat treatment (t = 72 °C exposure for 20 s) contributed to the reduction of mesophilic bacteria by 93.4% when using extra grade milk and by 91.5% when using first grade milk. That is, almost 6.4 times more bacteria remain in drinking milk when raw materials of lower quality are used. The intensity of death of heat-resistant microflora of milk under the regime of 72 °C with a holding time of 20 s was only 15.2 % when using raw extra milk and 4.2 % (first). Pasteurization at a temperature of 91 °C for 20 seconds had a much stronger effect on this microflora, as its efficiency was 52.9 % and 49.2 %. That is, the efficiency of the pasteurization mode was 3.5 and 11.7 times stronger, respectively, compared to the mode at a temperature of 72 °C. Therefore, in order to apply an effective pasteurization regime at the enterprise, it is necessary to know the quantitative and qualitative composition of the microflora of raw milk.

Effect of plant extracts on quality characteristics and shelf-life of cold-marinated shrimp (Parapenaeus longirostris, Lucas, 1846) under refrigerated storage

The effects of rosemary (Rosmarinus officinalis), lemon balm (Melissa officinalis), lavender (Lavandula angustifola), oregano (Origanum vulgare) and savory (Satureja montana) extracts, alone and in mixtures, on lipid oxidation in cold-marinated shrimp (Parapenaeus longirostris) were studied. During the two-month screening period using the thiobarbituric reactive substances assay (TBARS) the most effective extract mixture (rosemary:oregano:lavender extracts in 3:2:1 ratio, ROL) was selected for the shelf-life study in pilot production of marinated shrimp to determine its effects on the quality characteristics of the final product. Degradation of the omega-3 fatty acids, eicosapentaeonic acid (EPA) and docosahexaenoic acid (DHA) during 8 months of refrigerated storage, was inhibited in shrimp marinated with ROL compared to control samples. In addition, lower levels of total volatile basic nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) were observed in shrimp treated with extracts while the TBARS values remained below the limit of 3 μmol malondialdehyde (MDA)/100g during the 8-month shelf-life study period, whereas the control sample exceeded this value in the third month. The total number of aerobic mesophilic and psychrophilic microorganisms was reduced after marinating with extracts. The obtained results are promising with regard to the application of plant extracts, especially the tested ROL mixture, to extend the shelf-life of food products and to reduce lipid oxidation and microbial load in the food model.

Caracterização microbiológica de duas espécies de peixes neotropicais oriundas de área quilombola maranhense, Brasil

The aim of study is to feature the microbiological quality of two neotropical fish species from the quilombola area of Maranhão State, Brazil. In order to do so, 21 samples of Hoplerythrinus unitaeniatus and 21 samples of Cichlasoma bimaculatum were captured in flooded environment. Collected fish were euthanized in laboratory environment; muscle fragments were removed for microbiological analyses focused on enumerating molds and yeasts, viable strict and facultative mesophilic microorganisms and coagulase-positive staphylococci; on counting total and thermotolerant coliforms; and on investigating Escherichia coli and Salmonella sp. Microbiological results were compared to the Brazilian legislation, which establishes the list of microbiological standards for food products. Among the assessed fish, 9.52% were classified as non-acceptable for human consumption, based on the Salmonella parameter. Enumerated coagulase-positive staphylococci ranged from < 10 to 3.9 x 104 CFU/g; 9.52% of assessed fish were classified as having intermediate standard for human consumption, whereas 4.76% were classified as non-acceptable for such a purpose. E. coli counting ranged from 3.6 to > 1,100MPN/g; 4.76% of assessed fish were classified as having intermediate standard for human consumption, whereas 4.76% were classified as non-acceptable for such a purpose. Total and thermotolerant coliforms’ counting and the enumeration of viable strict and facultative aerobic microorganisms, as well as of molds and yeasts, have evidenced high microbial population rates; this finding suggests poor hygienic conditions at capture site, contaminated raw material and risk of incidence of enteropathogens. This finding has evidenced imbalance in the investigated environment, as well as compromised aquatic biodiversity.