A newly isolated bacterium identified as Bacillus safensis based on biochemical tests and 16S rRNA analysis and its mutant variant created by exposure to ultraviolet radiation at 254 nm were investigated for keratinolytic activity. The wild-type strain produced 35.4–50.4 U/mL keratinase over a period of 120 h, while the mutant one yielded 64.4–108.5 U/mL keratinase for the same period of 120 h. The optimal conditions for the enzyme activities were pH 7.5 and 40 °C. The mutant and wild-type strain keratinases retained 59% and 54% of their activity after 12 h pretreatment at 40 °C, and 64% and 60% of their activity after 12 h at pH 7.5, respectively. The keratinases showed high substrate specificity for feathers, but low specificity for human and bovine hairs. The enzymes were activated by Na+, Ca2+, Fe2+ and Mg2+. However, while Mn2+ activated the enzyme from the mutant strain, it inhibited that of the wild type. The mutant and wild-type strain completely degraded whole chicken feathers after 6 and 9 days ...

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Bacillus safensis LAU 13: a new source of keratinase and its multi-functional biocatalytic applications

A newly isolated bacterium identified as Bacillus safensis based on biochemical tests and 16S rRNA analysis and its mutant variant created by exposure to ultraviolet radiation at 254 nm were investigated for keratinolytic activity. The wild-type strain produced 35.450.4 U/mL keratinase over a period of 120 h, while the mutant one yielded 64.4108.5 U/mL keratinase for the same period of 120 h. The optimal conditions for the enzyme activities were pH 7.5 and 40 C. The mutant and wild-type strain keratinases retained 59% and 54% of their activity after 12 h pretreatment at 40 C, and 64% and 60% of their activity after 12 h at pH 7.5, respectively. The keratinases showed high substrate specificity for feathers, but low specificity for human and bovine hairs. The enzymes were activated by Na C ,C a 2C ,F e 2C and Mg 2C . However, while Mn 2C activated the enzyme from the mutant strain, it inhibited that of the wild type. The mutant and wild-type strain completely degraded whole chicken feathers after 6 and 9 days at 30 § 2 C, and also completely dehaired goat skin within 12 and 16 h, respectively, without damage to the skin. Similarly, remarkable destaining of blood-stained cloth occurred within 23 h. The obtained results showed an improvement in the properties of the mutant strain for use of the microorganism or its enzyme as biocatalysts.

ARTICLE; AGRICULTURE AND ENVIRONMENTAL BIOTECHNOLOGY Bacillus safensis LAU 13: a new source of keratinase and its multi-functional biocatalytic applications

A new feather-degrading bacterium PKD 5 was isolated from feather dumping soil and identified as Bacillus weihenstephanensis based on morphological and physiochemical characteristics as well as 16S rRNA gene analysis. Extracellular keratinase was produced during submerged aerobic cultivation in a medium containing chicken feather as sole carbon and energy source and supplemented with salt solutions (NaCl 5.0, MgSO4 1.0, K2HPO4 1.0, (NH4)2SO4, 2.0 g/l). The optimal conditions for keratinase production include initial pH of 7.0, inoculum size of 2% (v/v), and cultivation at 40 °C. The maximum keratinase production and keratinolytic activity of PKD 5 was achieved after 7 days of fermentation under shaking condition (120 rpm). The enzyme has found application in developing cost-effective feather by-products for feeds and fertilizers. The manuscript first time describes B. weihenstephanensis PKD 5-mediated keratinase production under submerged fermentation and whole chicken feather biodegradation.

Keratinase production and biodegradation of whole chicken feather keratin by a newly isolated bacterium under submerged fermentation.

Microbial keratinases: An overview of biochemical characterization and its eco-friendly approach for industrial applications

Accumulation of feather waste is becoming a major issue in solid waste management. Towards discovery of keratinolytic bacteria, screening of bacterial strains from feather dumping sites in North East, India was performed and 26 keratinolytic bacterial strains were isolated. Out of these, one isolate RCM-SSR-7 was found to be most promising strain exhibiting feather degradation as well as antioxidant and indole-3-acetic acid production. The strain was identified as Chryseobacterium sediminis RCM-SSR-7. The strain could use chicken feather as sole carbon and nitrogen source for growth. Three parameters (feather concentration, pH and incubation time) were studied to optimize feather protein hydrolysate (FPH) preparation using response surface methodology (RSM). The optimum condition for FPH preparation was achieved at 5% (w/v) feather concentration, pH 7.5, 30 °C and 84 h incubation time upon optimization by RSM. FPH was found to be rich in essential amino acids and trace elements (phosphorous, potassium, calcium, and iron). FPH exhibited radical scavenging activity with an IC50 value of 0.102 mg ml−1. In vitro digestibility showed that FPH is 86% digestible with pepsin and trypsin treatment. This study revealed that FPH produced by C. sediminis RCM-SSR-7 has the potential to be used as animal feed and organic fertilizer.

Transforming Chicken Feather Waste into Feather Protein Hydrolysate Using a Newly Isolated Multifaceted Keratinolytic Bacterium Chryseobacterium sediminis RCM-SSR-7

A novel bacterium, Bacillus licheniformis K-19, which produces a large amount of akeratinase that is extremely thermostable and has a broad resistance to pH, was isolated and characterized. The maximum amount of keratinase activity (about 224 Uml-1) was produced at 37°C when the bacterium was cultured for 72 h in broth containing feather meal with initial pH of 7.5. The keratinase activity was observed over a wide range of temperatures (30 - 90°C) and pH values (pH 6 - 10). It was optimal at 60°C and pH 7.5 - 8 respectively. These results suggest potential biotechnological applications of this bacterium that involve hydrolysis of keratin, including the improvement of the nutritional properties of feathers (and other keratins) used as supplementary feedstuffs.

	 

	Key words: Bacillus licheniformis, chicken feather, keratin, keratinolytic protease.

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Isolation and characterization of a new keratinolytic bacterium that exhibits significant feather-degrading capability

The invention relates to a keratinase generating bacteria and it's preparing method. The systematic name is Bacillus subtilis with the registration number: CGMCC No.1505. It sieves the best strains of the keratinase whose best PH value of the course enzyme liquid enzyme reaction is about 7.5-8.0 and the best temperature is 50-60 deg. It keeps the temperature in 70 deg. water-bath with 30 min, the surplus enzyme is about 90%; it keeps the temperature with 120 min, the surplus enzyme is about 70%.

Keratinase-proudicng bacterium and its preparation method

Abstract Bacterial blight (BB), a serious bacterial disease caused by pathogen Xanthomonas oryzae pv. oryzae ( Xoo ) affects rice growth and yield. Yunnan Province is regarded as a center of rice diversity in China and indeed the world, and has abundant rice landrace resources, which may offer prospective candidate donors in rice improvement and breeding. In this study, a set of 200 rice landraces were evaluated to determine their resistance to 10 pathogenic Xoo strains resistance by the leaf-clipping method. The results indicated that the tested rice landraces had different resistance levels against different Xoo strains. Multiple comparisons showed that the Xoo strain PXO99 was virulent to the tested rice landraces. Sixty-six rice landraces conferred resistance against at least one Xoo strain. These resistant rice landraces screened were then performed the presence of 14 cloned BB resistance genes by closely linked molecular markers and designed specific primers. The results showed that none of these resistant accessions contained xa13 , Xa21 , Xa27 , and Xa45(t) homologous fragments, while 9, 24, 4, 7, 9, 15, 1, 5, 4 and 27 accessions contained Xa1 , Xa2/Xa31(t) , Xa14 , Xa3/Xa26 , Xa4 , xa5 , Xa7 , Xa10 , Xa23 and xa25 homologous fragments, respectively. Sequence analysis further revealed that nucleotide variations around functional nucleotide polymorphisms region were observed within these accessions containing the Xa1 , Xa2/Xa31(t) , Xa14 , Xa3/Xa26 , Xa4 , xa5 , Xa10 , Xa23 and xa25 homologous fragments. These results along with phenotypic resistance spectrum supported that these accessions carried nine resistance homologous genes. Only one accession (Qishanggu_Wenshan) carried the Xa7 resistance gene. We also found that some resistant rice landraces, especially Xilandigu_Baoshan, and Laoyaling_Lincang without the above resistance genes, which mediated broad spectrum resistance to multiple Xoo strains, were identified as potential sources for breeding rice lines resistance to BB. 

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Identification of bacterial blight resistance genes in rice landraces from Yunnan Province, China

Bacterial blight (BB) induced by Xanthomonas oryzae pv. oryzae (Xoo) is a devastating bacterial disease in rice. The use of disease resistance (R) genes is the most efficient method to control BB. Members of the nucleotide-binding domain and leucine-rich repeat containing protein (NLR) family have significant roles in plant defense. In this study, Xa47, a new bacterial blight R gene encoding a typical NLR, was isolated from G252 rice material, and XA47 was localized in the nucleus and cytoplasm. Among 180 rice materials tested, Xa47 was discovered in certain BB-resistant materials. Compared with the wild-type G252, the knockout mutants of Xa47 was more susceptible to Xoo. By contrast, overexpression of Xa47 in the susceptible rice material JG30 increased BB resistance. The findings indicate that Xa47 positively regulates the Xoo stress response. Consequently, Xa47 may have application potential in the genetic improvement of plant disease resistance. The molecular mechanism of Xa47 regulation merits additional examination.

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A new NLR disease resistance gene Xa47 confers durable and broad-spectrum resistance to bacterial blight in rice

Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is among the oldest known bacterial diseases found for rice in Asia. It is the most serious bacterial disease in many rice growing regions of the world. A total of 47 resistance (R) genes (Xa1 to Xa47) have been identified. Nonetheless, these R genes could possibly be defeated to lose their qualitative nature and express intermediate phenotypes. The identification of sources of novel genetic loci regulating host plant resistance is crucial to develop an efficient control strategy. Wild ancestors of cultivated rice are a natural genetic resource contain a large number of excellent genes. Medicinal wild rice (Oryza officinalis) belongs to the CC genome and is a well-known wild rice in south China. In this study, O. officinalis was crossed with cultivated rice HY-8 and their hybrids were screened for BB resistance genes deployed through natural selection in wild rice germplasm. The molecular markers linked to R genes for BB were used to screen the genomic regions in wild parents and their recombinants. The gene coding and promoter regions of major R genes were inconsistently found in O. officinalis and its progenies. Oryza officinalis showed resistance to all thirty inoculated Xoo strains with non-availability of various known R genes. The results indicated the presence of novel genomic regions for BB resistance in O. officinalis. The present study not only provides a reference to investigate medicinal rice for R gene(s) identification against BB but also identified it as a new breeding material for BB resistance.

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Qiaofang Zhong

Papers

Isolation and characterization of a new keratinolytic bacterium that exhibits significant feather-degrading capability

Keratinase-proudicng bacterium and its preparation method

Identification of bacterial blight resistance genes in rice landraces from Yunnan Province, China

A new NLR disease resistance gene Xa47 confers durable and broad-spectrum resistance to bacterial blight in rice

Unveiling a Novel Source of Resistance to Bacterial Blight in Medicinal Wild Rice, Oryza officinalis