I believe the citation shown below is the particular consolidation by Gardner that Powers was referring to. Gardner had only recently assumed command of Port Hudson.

It should be noted that this is one of only many consolidations [regimental and at brigade level] that had taken place among these Arkansas regiments since the Fort Donelson/Island #10 prisoner exchange and the Corinth debacle. Revised consolidations would continue in the coming months. These varying consolidations have been a particularly frustrating research project of mine for many years.

Official Records Vol XV, p 934-5
GENERAL ORDERS, HEADQUARTERS, No. 5.
Port Hudson, La., January 7, 1863.
The troops of this post will be organized into brigades, arranged at the breastworks as follows:
I. Brigadier General John Gregg's brigade to take post on the right, extending from the river; Brigadier General S. B. Maxey's brigade the center, and Brigadier General W. N. R. Beall's brigade the left.
II. Brigadier-General Maxey's brigade will consist of Col. w. R. Miles' Legion; the consolidated regiment consisting of the Forty-second, Forty-sixth, Forty-eighth, Fifty-third Tennessee Regiments, and Ninth Tennessee Battalion, commanded by Col. W. A. Quarles; the consolidated regiment consisting of the Forty-ninth, Fifty-fifth Tennessee, and the Seventh Texas Regiments, commanded by Col. J. E. Bailey; Col. Gus. A. Breaux's Thirtieth Louisiana Regiment, and Boone's, Roberts', and Fenner's batteries, and Colonel Allen's Fourth Louisiana Regiment.
III. Brigadier-General Beall's brigade will consist of the consolidated regiment consisting of the Fourteenth, Sixteenth, Seventeenth, Eighteenth, Twenty-third Arkansas Regiments, and First Arkansas Battalion, commanded by Col. R. H. Crockett; the consolidated regiment consisting of the Eleventh and Fifteenth Arkansas Regiments, commanded by Col. John L. Logan; the consolidated regiment consisting of the Twenty-seventh and Thirty-first Alabama Regiments and Sixth Alabama Battalion, commanded by Col. J. M. Simonton; the consolidated regiment consisting of Thirty-ninth and First Mississippi Regiments, commanded by Col. W. B. Shelby, and Abbay's, Herod's and Bradford's batteries.
IV. The heavy artillery and cavalry will remain as separate commands. The reports of each separate organization will be sent direct to these headquarters.
V. The previous organization of brigades will be discontinued, but the consolidated regiments will remain so consolidated until the strength of any one regiment will justify its separation.
VI. Consolidated morning reports will be sent in to these headquarters on Tuesdays and Fridays of each week, and reports of number and condition of arms and amount of ammunition will be sent in each Friday.
By command of Major General Frank Gardner:
---- ----,
Acting Assistant Adjutant-General.