<i>Exiguobacterium acetylicum</i> transformed poultry feathers into amino acids through an extracellular secretion of keratinolytic enzymes

Tutuka Dlume; Nonso E. Nnolim; Uchechukwu U. Nwodo; Tutuka Dlume; Nonso E. Nnolim; Uchechukwu U. Nwodo

doi:10.3934/bioeng.2024022

AIMS Bioengineering

2024, Volume 11, Issue 4: 489-505. doi: 10.3934/bioeng.2024022

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Research article

Exiguobacterium acetylicum transformed poultry feathers into amino acids through an extracellular secretion of keratinolytic enzymes

Patho-Biocatalysis Group (PBG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa

Received: 15 June 2024 Revised: 25 September 2024 Accepted: 22 October 2024 Published: 19 November 2024

The transition from a traditional linear economy to a circular model aims to create a more sustainable future by reducing the adverse effects of agro-waste on the environment. The present study evaluated the metabolic diversity of bacterial isolates from municipal dumpsites for keratinase production and poultry feather valorization. The bacterium with the highest keratinolytic activity was identified through 16S ribosomal ribonucleic acid (rRNA) gene sequencing. The exo-keratinase production by the bacterium was optimized, and the feather hydrolysate obtained from the fermentation process was analyzed for amino acids. Among the twelve bacteria isolated from the dumpsite's sample, three showed significant feather degradation and keratinase production of 89% (744.5 ± 9.19 U/mL), 58% (269 ± 15.55 U/mL), and 46% (195 ± 7.07 U/mL) for SSB-03, SSB-02, and HSB-02, respectively. Analysis of the 16S rRNA gene sequence revealed that SSB-03 has high sequence homology with Exiguobacterium acetylicum, and thus, it was identified as Exiguobacterium acetylicum FHBD (accession number MW165834). Strain FHBD fermentation medium exhibited the maximum keratinase activity (2934.54 ± 38.56 U/mL) and sulfhydryl group content (3.09 ± 0.02 mM) at 72 h under optimal process conditions of pH 5.0, temperature (35 °C), inoculum size (2% v/v), and feather (15 g/L). Amino acid analysis of the feather hydrolysate showed significant levels of glutamic acid, aspartic acid, glycine, arginine, serine, and proline, with respective concentrations of 1.58, 1.34, 1.29, 1.20, 1.12, and 0.93 (g/100 g of sample). The study's findings emphasize the potential of E. acetylicum FHBD in poultry feather valorization and keratinase production.

Keywords:

Citation: Tutuka Dlume, Nonso E. Nnolim, Uchechukwu U. Nwodo. Exiguobacterium acetylicum transformed poultry feathers into amino acids through an extracellular secretion of keratinolytic enzymes[J]. AIMS Bioengineering, 2024, 11(4): 489-505. doi: 10.3934/bioeng.2024022

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Abstract

Abbreviations

MSM:

Minimal salt media;

GCF:

Ground chicken feather;

PCR:

Polymerase chain reaction;

NCBI:

National Centre for Biotechnology Information;

BLAST:

Basic local alignment search tool

1. Introduction

Some special polynomials and numbers are diversely used in physics and engineering as well as in mathematics. For example, Bell polynomials play an important role in the studies of water waves which help energy development, mechanical engineering, marine/offshore engineering, hydraulic engineering, etc (see ^{[9,10,11,12,22]}). There are various ways of studying special numbers and polynomials, to mention a few, generating functions, combinatorial methods, $p$ -adic analysis, umbral calculus, differential equations, probability theory, special functions and analytic number theory (see ^[1,2]).

The aim of this paper is to introduce several special polynomials and numbers, and to study their explicit expressions, recurrence relations and identities involving those polynomials and numbers by using generating functions.

Indeed, we introduce Bell polynomials and numbers of the second kind (see (2.3), (2.5)) and poly-Bell polynomials and numbers of the second kind (see (4.1)). The generating function of Bell numbers of the second kind is the compositional inverse of the generating function of Bell numbers minus the constant term. Then Bell polynomials of the second kind are natural extensions of those numbers (see ^[23]). The poly-Bell polynomials of the second kind, which are defined with the help of polylogarithm, become the Bell polynomials of the second kind up to sign when the index of the polylogarithm is $k = 1$ .

We also consider degenerate versions of those numbers and polynomials, namely degenerate Bell numbers and polynomials of the second (see (3.3), (3.5)) and degenerate poly-Bell numbers and polynomials (see (5.1)), and derive similar results. It is worthwhile to note that degenerate versions of many special numbers and polynomials have been explored in recent years with aforementioned tools and many interesting arithmetical and combinatorial results have been obtained (see ^{[14,15,18,19,26]}). In fact, studying degenerate versions can be done not only for polynomials and numbers but also for transcendental functions like gamma functions. For the rest of this section, we recall the necessary facts that are needed throughout this paper.

The Stirling numbers of the first kind, $S_{1}(n, k)$ , are given by

$\begin{equation} \frac{1}{k!}\big(\log(1+t)\big)^{k} = \sum\limits_{n = k}^{\infty}S_{1}(n, k)\frac{t^{n}}{n!}, \quad (k\ge 0), \quad (\mathrm{see}\ [7, 25]), \end{equation}$

(1.1)

As the inversion formula of (1.1), the Stirling numbers of the second kind, $S_{2}(n, k),$ are given by

$\begin{equation} \frac{1}{k!}\big(e^{t}-1\big)^{k} = \sum\limits_{n = k}^{\infty}S_{2}(n, k)\frac{t^{n}}{n!}, \quad (k\ge 0), \quad (\mathrm{see}\ [3, 13-20]). \end{equation}$

(1.2)

It is well known that the Bell polynomials are defined as

$\begin{equation} \mathrm{Bel}_{n}(x) = \sum\limits_{k = 0}^{n}S_{2}(n, k)x^{k}, \quad (n\ge 0), \quad (\mathrm{see}\ [24, 25]). \end{equation}$

(1.3)

From (1.3), we note that

$\begin{equation} e^{x(e^{t}-1)} = \sum\limits_{n = 0}^{\infty}\mathrm{Bel}_{n}(x)\frac{t^{n}}{n!}, \quad (\mathrm{see}\ [4, 7, 8, 17, 27]). \end{equation}$

(1.4)

When $x = 1$ , $\mathrm{Bel}_{n} = \mathrm{Bel}_{n}(1), \ (n\ge 0)$ are called the Bell numbers.

For any $\lambda\in\mathbb{R}$ , the degenerate exponential function is given by

$\begin{equation} e_{\lambda}^{x}(t) = \sum\limits_{n = 0}^{\infty}\frac{(x)_{n, \lambda}}{n!}t^{n} , \quad (\mathrm{see}\ [5, 6, 7, 26, 27]), \end{equation}$

(1.5)

where $(x)_{0, \lambda} = 1, \ (x)_{n, \lambda} = x(x-\lambda)\cdots(x-(n-1)\lambda), \ (n\ge 1)$ .

When $x = 1$ , we write $e_{\lambda}(t) = e_{\lambda}^{1}(t)$ .

The degenerate Stirling numbers of the first kind are defined by

$\begin{equation} \frac{1}{k!}\big(\log_{\lambda}(1+t)\big)^{k} = \sum\limits_{n = k}^{\infty}S_{1, \lambda}(n, k)\frac{t^{n}}{n!}, \ (k\ge 0), \ (\mathrm{see}\ [15]), \end{equation}$

(1.6)

where

$\begin{equation} \log_{\lambda}(1+t) = \sum\limits_{n = 1}^{\infty}\lambda^{n-1}(1)_{n, 1/\lambda}\frac{t^{n}}{n!}, \quad (\mathrm{see}\ [15]). \end{equation}$

(1.7)

In view of (1.2), the degenerate Stirling numbers of the second kind are defined by

$\begin{equation} \frac{1}{k!}\big(e_{\lambda}(t)-1\big)^{k} = \sum\limits_{n = k}^{\infty}S_{2}(n, k)\frac{t^{n}}{n!}, \quad (\mathrm{see}\ [15]). \end{equation}$

(1.8)

In ^[17], the degenerate Bell polynomials are defined by

$\begin{equation} e_{\lambda}^{x}\big(e_{\lambda}(t)-1\big) = \sum\limits_{n = 0}^{\infty}\mathrm{Bel}_{n, \lambda}(x)\frac{t^{n}}{n!}. \end{equation}$

(1.9)

When $x = 1$ , $\mathrm{Bel}_{n, \lambda} = \mathrm{Bel}_{n, \lambda}(1), \ (n\ge 0)$ , are called the Bell numbers.

From (1.8) and (1.9), we note that

$\begin{equation} \mathrm{Bel}_{n, \lambda}(x) = \sum\limits_{k = 0}^{n}S_{2, \lambda}(n, k)(x)_{k, \lambda}, \ (n\ge 0), \ (\mathrm{see}\ [17]). \end{equation}$

(1.10)

The polylogarithm of index $k$ is given by

$\begin{equation} \mathrm{Li}_{k}(x) = \sum\limits_{n = 1}^{\infty}\frac{x^{n}}{n^{k}}, \quad (k\in\mathbb{Z}, \ |x| < 1), \quad(\mathrm{see}\ [3, 13, 14, 16, 21]). \end{equation}$

(1.11)

Note that $\mathrm{Li}_{1}(x) = -\log(1-x)$ .

Recently, the degenerate polylogarithm is defined as

$\begin{equation} \mathrm{Li}_{k, \lambda}(x) = \sum\limits_{n = 1}^{\infty}\frac{(-\lambda)^{n-1}(1)_{n, 1/\lambda}}{(n-1)!n^{k}}x^{n}, \quad(|x| < 1, \ k\in\mathbb{Z}), \quad(\mathrm{see}\ [15]). \end{equation}$

(1.12)

Note that $\mathrm{Li}_{1, \lambda}(x) = -\log_{\lambda}(1-x)$ .

Here we mention that, to our best knowledge, the results of this paper are new.

2. Bell polynomials of the second kind

From (1.4), we note that

$e^{x(e^{t}-1)} = \sum\limits_{n = 0}^{\infty}\mathrm{Bel}_{n}(x)\frac{t^{n}}{n!}$

Let $x = 1$ . Then we have

$\begin{equation} e^{e^{t}-1}-1 = \sum\limits_{n = 1}^{\infty}\mathrm{Bel}_{n}\frac{t^{n}}{n!}. \end{equation}$

(2.1)

Let $f(t) = e^{e^{t}-1}-1$ . Then the compositional inverse of $f(t)$ is given by

$\begin{equation} f^{-1}(t) = \log\big(1+\log(1+t)\big). \end{equation}$

(2.2)

We consider the new type Bell numbers, called Bell numbers of the second kind, defined by

$\begin{equation} \log\big(1+\log(1+t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n}\frac{t^{n}}{n!}. \end{equation}$

(2.3)

Now, we observe that

$\begin{align} &\log\big(1+\log(1+t)\big) = \sum\limits_{k = 1}^{\infty}\frac{(-1)^{k-1}}{k}\big(\log(1+t)\big)^{k} \\ & = \sum\limits_{k = 1}^{\infty}(-1)^{k-1}(k-1)!\frac{1}{k!}\big(\log(1+t)\big)^{k} = \sum\limits_{k = 1}^{\infty}(-1)^{k-1}(k-1)!\sum\limits_{n = k}^{\infty}S_{1}(n, k)\frac{t^{n}}{n!} \\ & = \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}(-1)^{k-1}(k-1)!S_{1}(n, k) \bigg)\frac{t^{n}}{n!}. \end{align}$

(2.4)

Therefore, by (2.3) and (2.4), we obtain the following theorem.

Theorem 1. For $n\ge 1$ , we have

$(-1)^{n-1}\mathrm{bel}_{n} = \sum\limits_{k = 1}^{n}(k-1)!{n \brack k},$

where ${n \brack k}$ are the unsigned Stirling numbers of the first kind.

Also, we consider the new type Bell polynomials, called Bell polynomials of the second kind, defined by

$\begin{equation} \mathrm{bel}_{n}(x) = \sum\limits_{k = 1}^{n}(-1)^{k-1}(k-1)!S_{1}(n, k)x^{k}, \quad (n\ge 1). \end{equation}$

(2.5)

From (2.5), we can derive the following equation.

$\begin{align} \sum\limits_{n = 1}^{\infty} \mathrm{bel}_{n}(x)\frac{t^{n}}{n!}& = \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}(-1)^{k-1}(k-1)!S_{1}(n, k)x^{k}\bigg)\frac{t^{n}}{n!} \\ & = \sum\limits_{k = 1}^{\infty}(-1)^{k-1}(k-1)!x^{k}\sum\limits_{n = k}^{\infty}S_{1}(n, k)\frac{t^{n}}{n!} \\ & = \sum\limits_{k = 1}^{\infty}\frac{(-1)^{k-1}k!}{k}x^{k}\frac{1}{k!}\big(\log(1+t)\big)^{k} \\ & = \sum\limits_{k = 1}^{\infty}\frac{(-1)^{k-1}}{k}x^{k}\big(\log(1+t)\big)^{k} = \log (1+x\log(1+t)). \end{align}$

(2.6)

Thus the generating function of Bell polynomials of the second kind is given by

$\begin{equation} \log\big(1+x\log(1+t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n}(x)\frac{t^{n}}{n!}. \end{equation}$

(2.7)

Note here that $\mathrm{bel}_{n} = \mathrm{bel}_{n}(1)$ . From (2.7), we note that

$\begin{equation} \frac{x}{\big(1+x\log(1+t)\big)(1+t)} = \frac{d}{dt}\log\big(1+x\log(1+t)\big) = \sum\limits_{n = 0}^{\infty}\mathrm{bel}_{n+1}(x)\frac{t^{n}}{n!} . \end{equation}$

(2.8)

Replacing $t$ by $e^{t}-1$ in (2.8), we get

$\begin{align} \frac{x}{1+xt}e^{-t}\ & = \ \sum\limits_{k = 0}^{\infty}\mathrm{bel}_{k+1}(x)\frac{1}{k!}\big(e^{t}-1\big)^{k} \\ & = \ \sum\limits_{k = 0}^{\infty}\mathrm{bel}_{k+1}(x)\sum\limits_{n = k} ^{\infty}S_{2}(n, k)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 0}^{\infty}\bigg(\sum\limits_{k = 0}^{n}\mathrm{bel}_{k+1}(x)S_{2}(n, k)\bigg)\frac{t^{n}}{n!}. \end{align}$

(2.9)

Taking $x = -1$ in (2.9), we have

$\begin{equation} \sum\limits_{n = 0}^{\infty}\bigg(\sum\limits_{k = 0}^{n}\mathrm{bel}_{k+1}(-1)S_{2}(n, k)\bigg)\frac{t^{n}}{n!} = -\frac{1}{1-t}e^{-t} = -\sum\limits_{n = 0}^{\infty}d_{n}\frac{t^{n}}{n!}, \end{equation}$

(2.10)

where $d_{n}$ is the derangement number (see ^[19]).

Therefore, by comparing the coefficients on both sides of (2.10), we obtain the following theorem.

Theorem 2. For $n\ge 0$ , we have

$\sum\limits_{k = 0}^{n}\mathrm{bel}_{k+1}(-1)S_{2}(n, k) = -d_{n}.$

Replacing $t$ by $e^{e^{t}-1}-1$ in (2.3), we get

$\begin{align} t& = \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k}\frac{1}{k!}\Big(e^{e^{t}-1}-1\Big)^{k} = \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k}\sum\limits_{j = k}^{\infty}S_{2}(j, k)\frac{1}{j!} \big(e^{t}-1\big)^{j} \\ & = \sum\limits_{j = 1}^{\infty}\sum\limits_{k = 1}^{j}\mathrm{bel}_{k}S_{2}(j, k)\sum\limits_{n = j}^{\infty}S_{2}(n, k)\frac{t^{n}}{n!} \\ & = \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{j = 1}^{n}\sum\limits_{k = 1}^{j}\mathrm{bel}_{k}S_{2}(j, k)S_{2}(n, j)\bigg)\frac{t^{n}}{n!}. \end{align}$

(2.11)

Thus we obtain following theorem.

Theorem 3. For $n\ge 2$ , we have

$\sum\limits_{j = 1}^{n}\sum\limits_{k = 1}^{j}\mathrm{bel}_{k}S_{2}(j, k)S_{2}(n, j) = 0, \, \, \, \mathrm{and}\, \, \, \mathrm{bel}_{1} = 1.$

Replacing $t$ by $e^{t}-1$ in (2.7), we get

$\begin{align} \log(1+xt)\ & = \ \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k}(x)\frac{1}{k!}\big(e^{t}-1\big)^{k} \\ & = \ \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k}(x)\sum\limits_{n = k}^{\infty}S_{2}(n, k)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}\mathrm{bel}_{k}(x)S_{2}(n, k)\bigg)\frac{t^{n}}{n!}. \end{align}$

(2.12)

On the other hand,

$\begin{equation} \log(1+xt) = \sum\limits_{n = 1}^{\infty}\frac{(-1)^{n-1}}{n}x^{n}t^{n}. \end{equation}$

(2.13)

Therefore, by (2.12) and (2.13), we obtain the following theorem.

Theorem 4. For $n\ge 1$ , we have

$x^{n} = \frac{(-1)^{n-1}}{(n-1)!}\sum\limits_{k = 1}^{n}\mathrm{bel}_{k}(x)S_{2}(n, k).$

In particular,

$1 = \frac{(-1)^{n-1}}{(n-1)!}\sum\limits_{k = 1}^{n}\mathrm{bel}_{k}S_{2}(n, k).$

3. Degenerate Bell polynomials of the second kind

From (1.3), we note that

$\begin{equation} e_{\lambda}\big(e_{\lambda}(t)-1\big)-1 = \sum\limits_{n = 1}^{\infty}\mathrm{Bel}_{n, \lambda}\frac{t^{n}}{n!}. \end{equation}$

(3.1)

Let $f_{\lambda}(t) = e_{\lambda}\big(e_{\lambda}(t)-1\big)-1$ . Then the compositional inverse of $f_{\lambda}(t)$ is given by

$\begin{equation} f_{\lambda}^{-1}(t) = \log_{\lambda}\big(1+\log_{\lambda}(1+t)\big). \end{equation}$

(3.2)

We consider the new type degenerate Bell numbers, called degenerate Bell numbers of the second kind, defined by

$\begin{equation} \log_{\lambda}\big(1+\log_{\lambda}(1+t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n, \lambda}\frac{t^{n}}{n!}. \end{equation}$

(3.3)

Now, we observe that

$\begin{align} \log_{\lambda}\big(1+\log_{\lambda}(1+t)\big)\ & = \ \sum\limits_{k = 1}^{\infty}\lambda^{k-1}(1)_{k, 1/\lambda}\frac{1}{k!}\big(\log_{\lambda}(1+t)\big)^{k} \\ & = \ \sum\limits_{k = 1}^{\infty}\lambda^{k-1}(1)_{k, 1/\lambda}\sum\limits_{n = k}^{\infty}S_{1, \lambda}(n, k)\frac{t^{n}}{n!}. \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}\lambda^{k-1}(1)_{k, 1/\lambda}S_{1, \lambda}(n, k)\bigg)\frac{t^{n}}{n!}. \end{align}$

(3.4)

Therefore, by (3.3) and (3.4), we obtain the following theorem.

Theorem 5. For $n\ge 1$ , we have

$\mathrm{bel}_{n, \lambda} = \sum\limits_{k = 1}^{n}\lambda^{k-1}(1)_{k, 1/\lambda}S_{1, \lambda}(n, k).$

Also, we define the degenerate Bell polynomials of second kind by

$\begin{equation} \mathrm{bel}_{n, \lambda}(x) = \sum\limits_{k = 1}^{n}\lambda^{k-1}(1)_{k, 1/\lambda}S_{1, \lambda}(n, k)x^{k}. \end{equation}$

(3.5)

Note that $\mathrm{bel}_{n, \lambda} = \mathrm{bel}_{n, \lambda}(1)$ .

From (3.5), we note that

$\begin{align} \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n, \lambda}(x)\frac{t^{n}}{n!}\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}\lambda^{k-1}(1)_{k, 1/\lambda}S_{1, \lambda}(n, k)x^{k}\bigg)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{k = 1}^{\infty}\lambda^{k-1}(1)_{k, 1/\lambda}x^{k}\sum\limits_{n = k}^{\infty}S_{1, \lambda}(n, k)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{k = 1}^{\infty}\lambda^{k-1}(1)_{k, 1/\lambda}x^{k}\frac{1}{k!}\big(\log_{\lambda}(1+t)\big)^{k} \\ & = \ \log_{\lambda}\big(1+x\log_{\lambda}(1+t)\big). \end{align}$

(3.6)

Thus the generating function of $\mathrm{bel}_{n, \lambda}(x)$ is given by

$\begin{equation} \log_{\lambda}\big(1+x\log_{\lambda}(1+t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n, \lambda}(x)\frac{t^{n}}{n!}. \end{equation}$

(3.7)

Replacing $t$ by $e_{\lambda}(t)-1$ in (3.7), we get

$\begin{align} \log_{\lambda}(1+xt)\ & = \ \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k, \lambda}(x)\frac{1}{k!}\big(e_{\lambda}(t)-1\big)^{k} \\ & = \ \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k, \lambda}(x)\sum\limits_{n = k}^{\infty}S_{2, \lambda}(n, k)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{n}\mathrm{bel}_{k, \lambda}(x)S_{2, \lambda}(n, k)\bigg)\frac{t^{n}}{n!}. \end{align}$

(3.8)

On the other hand,

$\begin{equation} \log_{\lambda}(1+xt) = \sum\limits_{n = 1}^{\infty}\lambda^{n-1}(1)_{n, 1/\lambda}x^{n}\frac{t^{n}}{n!}. \end{equation}$

(3.9)

Therefore, by (3.8) and (3.9), we obtain the following theorem.

Theorem 6. For $n\ge 1$ , we have

$x^{n} = \frac{\lambda^{1-n}}{(1)_{n, 1/\lambda}}\sum\limits_{k = 1}^{n}\mathrm{bel}_{k, \lambda}(x)S_{2, \lambda}(n, k).$

In particular,

$\lambda^{n-1}(1)_{n, 1/\lambda} = \sum\limits_{k = 1}^{n}\mathrm{bel}_{k, \lambda}S_{2, \lambda}(n, k).$

Replacing $t$ by $e_{\lambda}\big(e_{\lambda}(t)-1\big)-1$ in (3.3), we have

$\begin{align} t\ & = \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k, \lambda}\frac{1}{k!} \big(e_{\lambda}(e_{\lambda}(t)-1)-1\big)^{k} \\ & = \sum\limits_{k = 1}^{\infty}\mathrm{bel}_{k, \lambda}\sum\limits_{j = k}^{\infty}S_{2, \lambda}(j, k)\frac{1}{j!}\big(e_{\lambda}(t)-1\big)^{j} \\ & = \ \sum\limits_{j = 1}^{\infty}\bigg(\sum\limits_{k = 1}^{j}\mathrm{bel}_{k, \lambda}S_{2, \lambda}(j, k)\bigg)\sum\limits_{n = j}^{\infty}S_{2, \lambda}(n, j)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{j = 1}^{n}\sum\limits_{k = 1}^{j}\mathrm{bel}_{k, \lambda}S_{2, \lambda}(j, k)S_{2, \lambda}(n, j)\bigg)\frac{t^{n}}{n!}. \end{align}$

(3.10)

Therefore, by comparing the coefficients on both sides of (3.10), we obtain the following theorem.

Theorem 7. For $n\ge 2$ , we have

$\sum\limits_{j = 1}^{n}\sum\limits_{k = 1}^{j}\mathrm{bel}_{k, \lambda}S_{2, \lambda}(j, k)S_{2, \lambda}(n, j) = 0, \, \, \, \mathrm{and}\, \, \, \mathrm{bel}_{1, \lambda} = 1.$

4. Poly-Bell polynomials of the second kind

Now, we consider the poly-Bell polynomials of the second kind which are defined as

$\begin{equation} \mathrm{Li}_{k}\big(-x\log(1-t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n}^{(k)}(x)\frac{t^{n}}{n!}. \end{equation}$

(4.1)

When $x = 1$ , $\mathrm{bel}_{n}^{(k)} = \mathrm{bel}_{n}^{(k)}(1)$ are called the poly-Bell numbers of the second kind.

From (1.11), we note that

$\begin{align} \mathrm{Li}_{k}\big(-x\log(1-t)\big)\ & = \ \sum\limits_{l = 1}^{\infty}\frac{(-1)^{l}}{l^{k}}x^{l}l!\frac{1}{l!}\big(\log(1-t)\big)^{l} \\ & = \ \sum\limits_{l = 1}^{\infty}\frac{(-1)^{l}}{l^{k-1}}(l-1)!x^{l}\sum\limits_{n = l}^{\infty}(-1)^{n}S_{1}(n, l)\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{l = 1}^{n}\frac{(-1)^{n-l}}{l^{k-1}}(l-1)!x^{l}S_{1}(n, l)\bigg)\frac{t^{n}}{n!}. \end{align}$

(4.2)

Therefore, by (4.1) and (4.2), we obtain the following theorem.

Theorem 8. For $n\ge 1$ , we have

$\mathrm{bel}_{n}^{(k)}(x) = \sum\limits_{l = 1}^{n}\frac{x^{l}}{l^{k-1}}(l-1)!{n \brack l}.$

In particular,

$\mathrm{bel}_{n}^{(k)} = \sum\limits_{l = 1}^{n}\frac{1}{l^{k-1}}(l-1)!{n \brack l}.$

Note that

$\mathrm{bel}_{n}^{(1)}(x) = \sum\limits_{l = 1}^{n}x^{l}(l-1)! {n \brack l} = (-1)^{n-1}\mathrm{bel}_{n}(x).$

Indeed,

$\begin{align*} \mathrm{Li}_{1}\big(-x\log(1-t)\big)\ & = \ -\log\big(1+x\log(1-t)\big) \\ & = \ \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n}(x)(-1)^{n-1}\frac{t^{n}}{n!}. \end{align*}$

Replacing $t$ by $1-e^{-t}$ in (4.1), we get

$\begin{align} \mathrm{Li}_{k}(xt)\ & = \ \sum\limits_{l = 1}^{\infty}\mathrm{bel}_{l}^{(k)}(x)\frac{1}{l!}\big(1-e^{-t}\big)^{l} \\ & = \ \sum\limits_{l = 1}^{\infty}\mathrm{bel}_{l}^{(k)}(x)(-1)^{l}\sum\limits_{n = l}^{\infty}S_{2}(n, l)(-1)^{n}\frac{t^{n}}{n!}. \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{l = 1}^{n}(-1)^{n-l}\mathrm{bel}_{l}^{(k)}(x)S_{2}(n, l)\bigg)\frac{t^{n}}{n!}. \end{align}$

(4.3)

From (1.11) and (4.3), we note that

$\begin{equation} \frac{x^{n}}{n^{k}} = \frac{1}{n!}\sum\limits_{l = 1}^{n}(-1)^{n-l}\mathrm{bel}_{l}^{(k)}(x)S_{2}(n, l). \end{equation}$

(4.4)

Therefore, by (4.4), we obtain the following theorem.

Theorem 9. For $n\ge 1$ , we have

$x^{n} = \frac{n^{k-1}}{(n-1)!}\sum\limits_{l = 1}^{n}(-1)^{n-l}\mathrm{bel}_{l}^{(k)}(x)S_{2}(n, l).$

5. Degenerate poly-Bell polynomials of the second kind

We define the degenerate poly-Bell polynomials of the second kind by

$\begin{equation} \mathrm{Li}_{k, \lambda}\big(-x\log_{\lambda}(1-t)\big) = \sum\limits_{n = 1}^{\infty}\mathrm{bel}_{n, \lambda}^{(k)}(x)\frac{t^{n}}{n!}. \end{equation}$

(5.1)

When $x = 1$ , $\mathrm{bel}_{n, \lambda}^{(k)} = \mathrm{bel}_{n, \lambda}^{(k)}(1)$ are called the degenerate poly-Bell numbers of the second.

From (2.1), we note that

$\begin{align} \mathrm{Li}_{k, \lambda}\big(-x\log_{\lambda}(1-t)\ & = \ \sum\limits_{l = 1}^{\infty}\frac{(-\lambda)^{l-1}(1)_{l, 1/\lambda}}{(l-1)!l^{k}}\big(-x\log_{\lambda}(1-t)\big)^{l} \\ & = \ -\sum\limits_{l = 1}^{\infty}\frac{(1)_{l, 1/\lambda}}{l^{k-1}}\lambda^{l-1}x^{l}\frac{1}{l!}\big(\log_{\lambda}(1-t)\big)^{l}. \\ & = -\sum\limits_{l = 1}^{\infty}\frac{(1)_{l, 1/\lambda}}{l^{k-1}}\lambda^{l-1}x^{l}\sum\limits_{n = l}^{\infty}S_{1, \lambda}(n, l)(-1)^{n}\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg((-1)^{n-1}\sum\limits_{l = 1}^{n}\frac{1}{l^{k-1}}(1)_{l, 1/\lambda}\lambda^{l-1}x^{l}S_{1, \lambda}(n, l)\bigg)\frac{t^{n}}{n!}. \end{align}$

(5.2)

Therefore, by (5.1) and (5.2), we obtain the following theorem.

Theorem 10. For $n\ge 1$ , we have

$(-1)^{n-1}\mathrm{bel}_{n, \lambda}^{(k)}(x) = \sum\limits_{l = 1}^{n}\frac{1}{l^{k-1}}(1)_{l, 1/\lambda}\lambda^{l-1}x^{l}S_{1, \lambda}(n, l).$

For $k = 1$ , we have

$(-1)^{n-1}\mathrm{bel}_{n, \lambda}^{(1)}(x) = \sum\limits_{l = 1}^{n}(1)_{l, 1/\lambda}\lambda^{l-1}x^{l}S_{1, \lambda}(n, l) = \mathrm{bel}_{n, \lambda}(x), \quad (n\ge 0).$

Indeed,

$\mathrm{Li}_{1, \lambda}\big(-x\log_{\lambda}(1-t)\big) = -\log_{\lambda}\big(1+x\log_{\lambda}(1-t)\big) = \sum\limits_{n = 1}^{\infty}(-1)^{n-1}\mathrm{bel}_{n, \lambda}(x)\frac{t^{n} }{n!}.$

Replacing $t$ by $1-e_{\lambda}(-t)$ in (5.1), we get

$\begin{align} \mathrm{Li}_{k, \lambda}(xt)\ & = \ \sum\limits_{l = 1}^{\infty} \mathrm{bel}_{l, \lambda}^{(k)}(x)\frac{1}{l!}\big(1-e_{\lambda}(-t)\big)^{l} \\ & = \ \sum\limits_{l = 1}^{\infty} \mathrm{bel}_{l, \lambda}^{(k)}(x)(-1)^{l}\frac{1}{l!}\big(e_{\lambda}(-t)-1\big)^{l} \\ & = \ \sum\limits_{l = 1}^{\infty} \mathrm{bel}_{l, \lambda}^{(k)}(x)(-1)^{l}\sum\limits_{n = l}^{\infty}S_{2, \lambda}(n, l)(-1)^{n}\frac{t^{n}}{n!} \\ & = \ \sum\limits_{n = 1}^{\infty}\bigg(\sum\limits_{l = 1}^{n}(-1)^{n-l} \mathrm{bel}_{l, \lambda}^{(k)}(x)S_{2, \lambda}(n, l)\bigg)\frac{t^{n}}{n!}. \end{align}$

(5.3)

On the other hand,

$\begin{equation} \mathrm{Li}_{k, \lambda}(xt) = \sum\limits_{n = 1}^{\infty}\frac{(-\lambda)^{n-1}(1)_{n, 1/\lambda}}{(n-1)!n^{k}}x^{n}t^{n} = \sum\limits_{n = 1}^{\infty}\frac{(-\lambda)^{n-1}(1)_{n, 1/\lambda}}{n^{k-1}}x^{n}\frac{t^{n}}{n!}. \end{equation}$

(5.4)

From (5.3) and (5.4), we get the following result.

Theorem 11. For $n \ge 1$ , we have

$\frac{(-\lambda)^{n-1}(1)_{n, 1/\lambda}}{n^{k-1}}x^{n} = \sum\limits_{l = 1}^{n}(-1)^{n-l}\mathrm{bel}_{l, \lambda}^{(k)}(x)S_{2, \lambda}(n, l).$

6. Conclusions

Many special polynomials and numbers are widely used in physics and engineering as well as in mathematics. In recent years, degenerate versions of some special polynomials and numbers have been studied by means of various different tools. Here we introduced Bell polynomials of the second kind, poly-Bell polynomials of the second kind and their degenerate versions, namely degenerate Bell polynomials of the second kind and degenerate poly-Bell polynomials of the second kind. By using generating functions, we explored their explicit expressions, recurrence relations and some identities involving those polynomials and numbers.

It is one of our future projects to continue this line of research, namely to explore many special numbers and polynomials and their degenerate versions with the help of various different tools.

Acknowledgments

This work was supported by the Basic Science Research Program, the National Research Foundation of Korea, (NRF-2021R1F1A1050151).

Conflict of interest

The authors declare no conflict of interest.

Acknowledgments

This work was supported by the Industrial Biocatalysis Hub, funded by the Department of Science and Innovation and the Technology Innovation Agency. The authors would also like to appreciate the funding support from the Infectious Diseases and Medicinal Plants Research Niche Area, University of Fort Hare.

Conflict of interest

The authors declare no conflict of interest.

Author contributions

Conceptualization: Nnolim Nonso, Uchechukwu Nwodo; Methodology: Tutuka Dlume, Nonso Nnolim; Formal analysis and investigation: Nonso Nnolim; Writing-original draft preparation: Tutuka Dlume; Writing-review and editing: Nonso Nnolim, Uchechukwu Nwodo; Funding acquisition: Uchechukwu Nwodo; Resources: Uchechukwu Nwodo; Supervision: Nonso Nnolim, Uchechukwu Nwodo.

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AIMS Bioengineering

Exiguobacterium acetylicum transformed poultry feathers into amino acids through an extracellular secretion of keratinolytic enzymes

Related Papers:

Abstract

1. Introduction

2. Bell polynomials of the second kind

3. Degenerate Bell polynomials of the second kind

4. Poly-Bell polynomials of the second kind

5. Degenerate poly-Bell polynomials of the second kind

6. Conclusions

Acknowledgments

Conflict of interest

References

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Abstract

1. Introduction

2. Bell polynomials of the second kind

3. Degenerate Bell polynomials of the second kind

4. Poly-Bell polynomials of the second kind

5. Degenerate poly-Bell polynomials of the second kind

6. Conclusions

Acknowledgments

Conflict of interest

References

AIMS Bioengineering

Exiguobacterium acetylicum transformed poultry feathers into amino acids through an extracellular secretion of keratinolytic enzymes

Related Papers:

Abstract

1. Introduction

2. Bell polynomials of the second kind

3. Degenerate Bell polynomials of the second kind

4. Poly-Bell polynomials of the second kind

5. Degenerate poly-Bell polynomials of the second kind

6. Conclusions

Acknowledgments

Conflict of interest

References

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Abstract

1. Introduction

2. Bell polynomials of the second kind

3. Degenerate Bell polynomials of the second kind

4. Poly-Bell polynomials of the second kind

5. Degenerate poly-Bell polynomials of the second kind

6. Conclusions

Acknowledgments

Conflict of interest

References