Effects of a monocomponent protease from Bacillus licheniformis on broiler performance, digestibility, and carcass yield

Two experiments were carried out to evaluate the effectsof protease addition to the diet of broilers at a higher level (1× or 2×) thanthe nutritional value proposed for the enzyme. The first experiment, 1280 day-old chicks (Cobb500®) were randomly allocated (randomized block design, 2×2+1 factorial arrangement),five treatments, eight replicates containing32 birds/replicate. Treatmentsconsisted: control diet without protease (CD); CD + 1× nutritional value of the enzyme (CDM1); CD + 2× nutritional value of the enzyme (CDM2); CDM1 + protease; and CDM2 + protease. The experimental period was 42 days. The mean weight (AFW), feed intake (FI), weight gain (WG), feed conversion, and carcass yield were evaluated. Significant differences were observed for AFW, WG, FI, abdominal fat yield, and feet percentage in the carcass. In the second experiment, 120 Cobb500®chicks at 14 days of age were allotted in a completely randomized design, 2×2+1 factorial arrangement, five treatments, six replicates withfour birds/replicate. The treatments were consistent with the first experiment. Significant improvements in the nitrogen balance wereobserved for the broilersthat received protease.The use of the enzyme tested is recommended with the recommended nutritional matrix, improving the zootechnical indices of broilers.(AU)

Evaluation of antibacterial activity of vitamin C against human bacterial pathogens / Avaliação da atividade antibacteriana da vitamina C contra patógenos bacterianos humanos

Now a day’s multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.

Agora, a resistência antimicrobiana de um dia em patógenos aos antibióticos tornou-se a principal causa de preocupação e houve uma realização inadequada no desenvolvimento de novos antibióticos para tratar infecções bacterianas. Portanto, há uma necessidade de pesquisar um novo adjuvante, e a vitamina C é um desses adjuvantes promissores. O objetivo do presente estudo foi elucidar o efeito antibacteriano da vitamina C em diferentes temperaturas (4 °C, 37 °C e 50 °C) e pH (3, 8 e 11), contra Gram-positivos e Gram-cepas bacterianas negativas em várias concentrações (5-20 mg / ml) através do método de difusão em ágar bem. A inibição do crescimento de todas as cepas bacterianas pela vitamina C era dependente da concentração. A vitamina C inibiu significativamente o crescimento de bactérias Gram-positivas: Bacillus licheniformis (25,3 ± 0,9 mm), Staphylococcus aureus (22,0 ± 0,6 mm), Bacillus subtilis (19,3 ± 0,3 mm) e bactérias Gram- negativas: Proteus mirabilis (27,7 ± 0,9 mm), Klebsiella pneumoniae (21,3 ± 0,9 mm), Pseudomonas aeruginosa (18,0 ± 1,5 mm) e Escherichia coli (18,3 ± 0,3 mm). A estabilidade da vitamina C foi observada em vários valores de pH e várias temperaturas. A vitamina C mostrou atividade antibacteriana significativa em pH ácido contra todas as cepas bacterianas. A estabilidade da vitamina C permaneceu nas mesmas diferentes temperaturas (4 °C, 37 °C e 50 °C). Concluímos que a vitamina C é um agente antibacteriano eficaz e seguro que pode ser usado no futuro como uma opção de tratamento auxiliar para combater infecções em humanos, pois pode apoiar o sistema imunológico diretamente.

Evaluation of antibacterial activity of vitamin C against human bacterial pathogens / Avaliação da atividade antibacteriana da vitamina C contra patógenos bacterianos humanos

Now a days multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.(AU)

Agora, a resistência antimicrobiana de um dia em patógenos aos antibióticos tornou-se a principal causa de preocupação e houve uma realização inadequada no desenvolvimento de novos antibióticos para tratar infecções bacterianas. Portanto, há uma necessidade de pesquisar um novo adjuvante, e a vitamina C é um desses adjuvantes promissores. O objetivo do presente estudo foi elucidar o efeito antibacteriano da vitamina C em diferentes temperaturas (4 °C, 37 °C e 50 °C) e pH (3, 8 e 11), contra Gram-positivos e Gram-cepas bacterianas negativas em várias concentrações (5-20 mg / ml) através do método de difusão em ágar bem. A inibição do crescimento de todas as cepas bacterianas pela vitamina C era dependente da concentração. A vitamina C inibiu significativamente o crescimento de bactérias Gram-positivas: Bacillus licheniformis (25,3 ± 0,9 mm), Staphylococcus aureus (22,0 ± 0,6 mm), Bacillus subtilis (19,3 ± 0,3 mm) e bactérias Gram- negativas: Proteus mirabilis (27,7 ± 0,9 mm), Klebsiella pneumoniae (21,3 ± 0,9 mm), Pseudomonas aeruginosa (18,0 ± 1,5 mm) e Escherichia coli (18,3 ± 0,3 mm). A estabilidade da vitamina C foi observada em vários valores de pH e várias temperaturas. A vitamina C mostrou atividade antibacteriana significativa em pH ácido contra todas as cepas bacterianas. A estabilidade da vitamina C permaneceu nas mesmas diferentes temperaturas (4 °C, 37 °C e 50 °C). Concluímos que a vitamina C é um agente antibacteriano eficaz e seguro que pode ser usado no futuro como uma opção de tratamento auxiliar para combater infecções em humanos, pois pode apoiar o sistema imunológico diretamente.(AU)

Artificial intelligence applied to enzymatic hydrolysis of lactose: improving the control of industrial processes / Inteligência artificial aplicada a hidrólise enzimática da lactose: melhorando o controle dos processos industriais

Lactose is the main carbohydrate in milk, and its absorption occurs via enzymatic hydrolysis, generating glucose and galactose. Lactose intolerance is the reduction of intestinal hydrolysis capacity due to hypolactasia, which results in the need to consume dairy foods with low levels of this carbohydrate. ß-galactosidase enzymes are used in dairy industries to hydrolyze lactose, thereby allowing intolerant consumers access to dairy products without the negative health implications. Alternative and official analytical methods are used to quantify the carbohydrate content resulting from enzymatic hydrolysis. The objective of this study was to evaluate the enzymatic hydrolysis of two distinct industrial enzymes produced by the microorganisms Bacillus licheniformis and Kluyveromyces lactis using three analytical methods: enzymatic method, cryoscopy, and high performance liquid chromatography (HPLC) using artificial intelligence to improve the control of the industrial processes. After adding the enzymes to skim milk, time kinetics was performed by collecting samples at time 0, every 10 min for 1 h, and every 30 min until the end of 5 h of hydrolysis. In 97% of the cases, a decrease in lactose concentration was observed by HPLC, followed by the deepening of the cryoscopic point. Glucose measurements by absorbance and HPLC quantification were correlated (r = 0.79; p < 0.01) but not concordant (p < 0.01). It was concluded that by means of artificial intelligence, it was possible to indirectly estimate lactose concentration using an algorithm that associates cryoscopy and glucose concentration.(AU)

O principal carboidrato do leite é a lactose e a sua absorção ocorre devido à hidrólise enzimática, gerando glicose e galactose. A intolerância à lactose é a redução da capacidade de hidrólise intestinal devido à hipolactasia, gerando a necessidade do consumo de alimentos lácteos com baixo teor deste carboidrato. As enzimas ß-galactosidase são utilizadas nas indústrias de laticínios para hidrolisar a lactose, proporcionando ao consumidor intolerante a possibilidade de ingerir os produtos lácteos sem prejuízos à saúde. Para quantificar o conteúdo de carboidratos resultante da hidrólise enzimática, são utilizados métodos analíticos alternativos e oficiais. O objetivo deste estudo foi avaliar a hidrólise enzimática de duas enzimas industriais distintas produzidas pelos microrganismos Bacillus licheniformis e Kluyveromyces lactis, por meio de três métodos analíticos: método enzimático, crioscopia e HPLC. A inteligência artificial foi utilizada para melhorar o controle dos processos industriais. Após a adição das enzimas ao leite desnatado, foi realizada a cinética de tempo coletando as amostras no tempo 0, a cada 10 minutos, até completar 1 hora de reação, e a cada 30 minutos até serem atingidas 5 horas de reação de hidrólise. Em 97% dos casos, a diminuição da concentração de lactose por HPLC acompanhou o aprofundamento do ponto crioscópico. As medições de glicose por absorbância e HPLC foram correlacionadas (r = 0,79; p < 0,01), mas não concordantes (p < 0,01). Concluiu-se que, por meio da inteligência artificial, é possível estimar indiretamente a concentração de lactose a partir de um algoritmo que associa a crioscopia e a concentração de glicose.(AU)

Bacillus licheniformis SMIA-2 protease used as an additive in detergent formulations

Microbial proteases, especially from Bacillus spp., have been widely exploited for a broad variety of applications, such as the improvement of the cleaning efficiency of conventional detergents. In this work, the statistical design of the experiment was used to optimize the concentrations of a three-component mixture: Bacillus licheniformis SMIA-2 protease, Linear Alkylbenzene Sulphate and hydrogen peroxide, in an attempt to prepare an environmentally correct cleaning formulation. The results demonstrated that the combination of 1% (w/v) protease with 1.5% (w/v) LAS and 1% (w/v) H2O2 was effective in removing blood from cloth pieces and that a protease concentration decrease from 1.0% to 0.5% (w/v) would not have a signi&64257;cant impact on percent blood removal if LAS concentrations between 1.5-2.0% (w/v) in combination with lower (<0.5%, w/v) concentrations of H2O2 were used. Thus, the protease from Bacillus licheniformis SMIA-2 can be effectively incorporated into cleaning formulations together with LAS and hydrogen peroxide to formulate more sustainable detergents.

Bacillus licheniformis SMIA-2 protease used as an additive in detergent formulations

Microbial proteases, especially from Bacillus spp., have been widely exploited for a broad variety of applications, such as the improvement of the cleaning efficiency of conventional detergents. In this work, the statistical design of the experiment was used to optimize the concentrations of a three-component mixture: Bacillus licheniformis SMIA-2 protease, Linear Alkylbenzene Sulphate and hydrogen peroxide, in an attempt to prepare an environmentally correct cleaning formulation. The results demonstrated that the combination of 1% (w/v) protease with 1.5% (w/v) LAS and 1% (w/v) H2O2 was effective in removing blood from cloth pieces and that a protease concentration decrease from 1.0% to 0.5% (w/v) would not have a signi&64257;cant impact on percent blood removal if LAS concentrations between 1.5-2.0% (w/v) in combination with lower (<0.5%, w/v) concentrations of H2O2 were used. Thus, the protease from Bacillus licheniformis SMIA-2 can be effectively incorporated into cleaning formulations together with LAS and hydrogen peroxide to formulate more sustainable detergents.(AU)

Spoilage potential of spore-forming bacteria from refrigerated raw milk / Potencial deteriorante de bactérias formadoras de esporos do leite cru refrigerado

Aerobic bacterial spores are an important group of microorganisms in raw milk. These microbes are thermoduric, whereas the vegetative forms are thermophilic, thermoduric and psychrotrophic and reduce the shelf life of pasteurized milk. In Brazil, there are a lack of studies on the load of aerobic spores in raw milk; thus, little is known about the spoilage activity of these organisms. The aim the present study was to quantify the aerobic spores in Brazilian refrigerated raw milk of dairy region of Castro, Paraná state, assess the potential proteolytic and/or lipolytic isolates and identify the microorganisms derived from the germination. Twenty milk samples were evaluated, and the aerobic spore count was performed after plating the samples following heat treatment at 80ºC for 12 min. The activity proteolytic and lipolytic isolates were evaluated through subculture on milk agar and tributyrin agar, respectively, and these microorganisms were identified using partial 16S rRNA gene sequences that were compared through GenBank. The aerobic spore counts ranged from 1 to 3.7 log CFU.mL-¹, with a mean of 1.75 (± 0.59) log CFU.mL-¹. After spore germination, 137 aerobic bacterial isolates were obtained, 40 of which (29.2%) showed milk spoilage activity. Among these, 31 isolates (77.5%) were proteolytic and lipolytic, seven isolates (17.5%) were exclusively lipolytic and two isolates (5%) were only proteolytic. Based on the 16S rRNA gene analysis, Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) and Brevibacillus spp. (2.5%) were identified. Studies of Brazilian raw milk microbiota have not yet described B. circulans which are frequently detected in milk from other countries. Among the 22 B. licheniformis isolates, 21 microbes (95.5%) showed proteolytic and lipolytic activity, and one isolate (4.5%) exhibited only proteolytic activity. The two B. pumilus isolates were proteolytic...(AU)

Esporos de bactérias aeróbias são um importante grupo de micro-organismos no leite cru. Esses micro-organismos são termodúricos, e suas formas vegetativas são termofílicas, termodúricas e psicrotróficas e reduzem a vida útil do leite pasteurizado. No Brasil, não há estudos sobre os esporos aeróbios no leite cru, assim, pouco se sabe sobre o potencial deteriorante dessa microbiota no leite cru brasileiro. O objetivo do presente trabalho foi quantificar esporos aeróbios no leite cru refrigerado brasileiro, avaliar o seu potencial proteolítico e/ou lipolítico e identificar esses micro-organismos originários da germinação dos esporos. Foram avaliadas 20 amostras de leite cru refrigerado, nas quais foi realizada a contagem de esporos aeróbios após o tratamento térmico de 80ºC por 12 min. A atividade proteolítica e/ou lipolítica dos isolados foi avaliada após o repique das colônias em ágar leite e tributirina, respectivamente, e a identificação desses micro-organismos deteriorantes foi realizada pelo sequenciamento parcial do gene 16S rRNA e comparação com as sequencias depositadas no GenBank. As contagens de esporos aeróbios variaram de 1 a 3.7 log CFU.mL-¹, com média de 1.75 (± 0.59) log UFC.mL-¹. Após a germinação dos esporos, foram obtidas 137 colônias, das quais 40 (29.2%) apresentaram algum tipo de atividade deteriorante: 31 (77.5%) isolados foram proteolíticos e lipolíticos, sete (17.5%) foram exclusivamente lipolíticos e dois (5%) foram apenas proteolíticos. Baseado nas sequencias do gene 16S rRNA, foram identificados Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) e Brevibacillus spp. (2.5%) entre os esporulados deteriorantes. Estudos preliminaries sobre a microbiota do leite brasileiro ainda não haviam descrito B. circulans e Paenibacillus, gêneros frequentemente descritos no leite de outros países. Entre os 22 B. licheniformis...(AU)

Spoilage potential of spore-forming bacteria from refrigerated raw milk / Potencial deteriorante de bactérias formadoras de esporos do leite cru refrigerado

Aerobic bacterial spores are an important group of microorganisms in raw milk. These microbes are thermoduric, whereas the vegetative forms are thermophilic, thermoduric and psychrotrophic and reduce the shelf life of pasteurized milk. In Brazil, there are a lack of studies on the load of aerobic spores in raw milk; thus, little is known about the spoilage activity of these organisms. The aim the present study was to quantify the aerobic spores in Brazilian refrigerated raw milk of dairy region of Castro, Paraná state, assess the potential proteolytic and/or lipolytic isolates and identify the microorganisms derived from the germination. Twenty milk samples were evaluated, and the aerobic spore count was performed after plating the samples following heat treatment at 80ºC for 12 min. The activity proteolytic and lipolytic isolates were evaluated through subculture on milk agar and tributyrin agar, respectively, and these microorganisms were identified using partial 16S rRNA gene sequences that were compared through GenBank. The aerobic spore counts ranged from 1 to 3.7 log CFU.mL-¹, with a mean of 1.75 (± 0.59) log CFU.mL-¹. After spore germination, 137 aerobic bacterial isolates were obtained, 40 of which (29.2%) showed milk spoilage activity. Among these, 31 isolates (77.5%) were proteolytic and lipolytic, seven isolates (17.5%) were exclusively lipolytic and two isolates (5%) were only proteolytic. Based on the 16S rRNA gene analysis, Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) and Brevibacillus spp. (2.5%) were identified. Studies of Brazilian raw milk microbiota have not yet described B. circulans which are frequently detected in milk from other countries. Among the 22 B. licheniformis isolates, 21 microbes (95.5%) showed proteolytic and lipolytic activity, and one isolate (4.5%) exhibited only proteolytic activity. The two B. pumilus isolates were proteolytic...

Esporos de bactérias aeróbias são um importante grupo de micro-organismos no leite cru. Esses micro-organismos são termodúricos, e suas formas vegetativas são termofílicas, termodúricas e psicrotróficas e reduzem a vida útil do leite pasteurizado. No Brasil, não há estudos sobre os esporos aeróbios no leite cru, assim, pouco se sabe sobre o potencial deteriorante dessa microbiota no leite cru brasileiro. O objetivo do presente trabalho foi quantificar esporos aeróbios no leite cru refrigerado brasileiro, avaliar o seu potencial proteolítico e/ou lipolítico e identificar esses micro-organismos originários da germinação dos esporos. Foram avaliadas 20 amostras de leite cru refrigerado, nas quais foi realizada a contagem de esporos aeróbios após o tratamento térmico de 80ºC por 12 min. A atividade proteolítica e/ou lipolítica dos isolados foi avaliada após o repique das colônias em ágar leite e tributirina, respectivamente, e a identificação desses micro-organismos deteriorantes foi realizada pelo sequenciamento parcial do gene 16S rRNA e comparação com as sequencias depositadas no GenBank. As contagens de esporos aeróbios variaram de 1 a 3.7 log CFU.mL-¹, com média de 1.75 (± 0.59) log UFC.mL-¹. Após a germinação dos esporos, foram obtidas 137 colônias, das quais 40 (29.2%) apresentaram algum tipo de atividade deteriorante: 31 (77.5%) isolados foram proteolíticos e lipolíticos, sete (17.5%) foram exclusivamente lipolíticos e dois (5%) foram apenas proteolíticos. Baseado nas sequencias do gene 16S rRNA, foram identificados Bacillus licheniformis (55%), Bacillus spp. (27.5%), Paenibacillus spp. (7.5%), Bacillus pumilus (5%), Bacillus circulans (2.5%) e Brevibacillus spp. (2.5%) entre os esporulados deteriorantes. Estudos preliminaries sobre a microbiota do leite brasileiro ainda não haviam descrito B. circulans e Paenibacillus, gêneros frequentemente descritos no leite de outros países. Entre os 22 B. licheniformis...

Isolation and identification of keratinolytic probiotic Bucillus licheniformis bacteria from the soil below poultry slaughterhouse waste / Isolamento e identificação de bactérias probióticas queratinolíticas Bacillus licheniformis do solo sob resíduos de abatedouro de aves

Feathers make up 7% of the total weight of adult chickens and keratin protein makes up 85% of the feathers. Today, the keratinase enzymes of some Bacillus strains are used to degrade and process raw keratin waste for animal and poultry feed. According to various studies, the probiotic properties of some spore-shaped Bacillus have also been proven. The study aimed to isolation of the keratinolytic Bacillus bacteria that they have probiotic properties for using in the livestock and poultry feed industry. We were able to isolate 8 strains of Bacillus licheniformis with kreatin degrading properties from the soil of Baharan chicken slaughterhouse (Qom city, Iran) applying heat shock, alcohol- and keratin-rich culture medium, and after microscopic and biochemical analysis, 16S rDNA gene was isolated. The measurement results of keratinase activity showed that the three strains of Bacillus licheniformis pvkr6, pvkr 15, and pvkr41 had the highest activity with 124.08, 101.1, and 100.18 U/ml. The results of probiotic properties evaluation also revealed that among all the isolates, only Bacillus licheniformis pvkr15 and Bacillus licheniformis PTCC 1595 (positive control) were γ-hemolytic strains. The percentage of surface hydrophobicity of the strains was obtained from 3.27 to 30.57. It was also shown that, on average, all the strains had acceptable susceptibility to the tested antibiotics except penicillin G. Bacillus licheniformis pvkr15 with highest keratinase activity (101.1U/ml) was considered an optional probiotics due to its abilities such as (biofilm formation, being safe cause of γ-hemolytic activity, high susceptibility to antibiotics such as streptomycin, gentamicin, cefixime, amoxicillin, tetracycline, vancomycin, erythromycin and having a moderate hydrophilic (hydrophobicity: 19.09%), high survivability in pH 2, 2.5 and 3, strong resistance to bile salts and moderate antagonistic activity against pathogenic bacterium like Proteus mirabilis and the ability to grow under anaerobic conditions). By using this strain, after hydrolysis of keratin protein in the feather structure, to replace part of the protein of livestock and poultry feed, not only is no need to separate bacteria from the feed, but also the strain play role of an useful and effective additive in animal growth.

As penas representam 7% do peso total das galinhas adultas e a proteína de queratina compõe 85% das penas. Hoje, as enzimas queratinase de algumas cepas de Bacillus são usadas para degradar e processar resíduos de queratina brutos para alimentação de animais e aves. De acordo com vários estudos, as propriedades probióticas de alguns Bacillus em forma de esporos também foram comprovadas. O estudo teve como objetivo o isolamento das bactérias queratinolíticas Bacillus que possuem propriedades probióticas para uso na indústria de ração animal e avícola. Conseguimos isolar 8 cepas de Bacillus licheniformis com propriedades degradantes de creatina do solo do abatedouro de frangos de Baharan (cidade de Qom, Irã) aplicando choque térmico, meio de cultura rico em álcool e queratina e, após análise microscópica e bioquímica, o gene 16S rDNA foi isolado. Os resultados da medição da atividade da queratinase mostraram que as três cepas de Bacillus licheniformis pvkr6, pvkr15 e pvkr41 tiveram a maior atividade com 124,08, 101,1 e 100,18 U/ml. Os resultados da avaliação das propriedades probióticas também revelaram que dentre todos os isolados apenas Bacillus licheniformis pvkr15 e Bacillus licheniformis PTCC 1595 (controle positivo) eram cepas γ-hemolíticas. A porcentagem de hidrofobicidade superficial das cepas foi obtida de 3,27 a 30,57. Também foi demonstrado que, em média, todas as cepas apresentaram suscetibilidade aceitável aos antibióticos testados, exceto penicilina G. Bacillus licheniformis pvkr15 com maior atividade de queratinase (101,1U/ml) foi considerado um probiótico opcional devido às suas habilidades como formação de biofilme, sendo causa segura de atividade γ-hemolítica, alta suscetibilidade a antibióticos como estreptomicina, gentamicina, cefixima, amoxicilina, tetraciclina, vancomicina, eritromicina e ter uma hidrofílica moderada (hidrofobicidade: 19,09%), alta capacidade de sobrevivência em pH 2, 2,5 e 3, forte resistência aos sais biliares e atividade antagonista moderada contra bactérias patogênicas como Proteus mirabilis e a capacidade de crescer em condições anaeróbicas. Ao utilizar esta cepa, após a hidrólise da proteína queratina na estrutura da pena, para substituir parte da proteína da ração de gado e aves, não só não há necessidade de separar as bactérias da ração, mas também a cepa desempenha um papel útil e eficaz aditivo no crescimento animal.